Update on the activity of Popocatepetl Volcano

 Mexico's geography in the Press  Comments Off on Update on the activity of Popocatepetl Volcano
May 102012
 

In the past few days, Popocatepetl Volcano has continued to emit gas, steam and ashes, periodically shooting ash-laden clouds high into the sky. The columns of ash have risen up to 2500 meters above the volcano before drifting downwind. Depending on the wind direction at the time, light falls of ash have been reported from Mexico City (especially the Milpa Alta and Iztapalapa districts) and the city of Puebla.

Ash cloud rises above Popocatepetl

Ash cloud rises above Popocatepetl Volcano

The National University’s Atmospheric Sciences Institute has developed atmospheric models taking account of the volcanic emissions and is releasing regular forecasts of where ash is likely to fall.

Ramón Espinasa Pereña, who heads the Geological Risks department in the National Disaster Prevention Centre (Centro Nacional de Prevención de Desastres, Cenapred) expressed concern recently that Popocatepetl Volcano could be headed towards much more significant activity in coming weeks.

In an interview with Mexico City daily Excelsior, Espinasa started by saying that that the current level of activity is less than that experienced in 2000 when the volcano’s heat caused the melting of the glacier then found on the northwest side of the mountain. However, he added, the situation today is quite different. The dome of lava inside the crater of Popocatepetl Volcano has been growing, increasing the risks of a significant and possibly explosive eruption. In 1994, prior to the 2000 eruption, the crater of the volcano was about 800 meters long, 600 meters wide and 100 meters deep. The activity in 2000 raised successive domes of lava in the crater to within 20 or 30 meters of the crater rim. So far this year, the depth of the crater has remained about the same, but only because almost all the new material being added to the existing domes is being blown into the air.

Experts are concerned that the high density of the magma beneath the volcano may lead to the existing vents being blocked. If this happens, pressure will build up underground and greatly increase the possibility of a violent eruption.

Evacuation plans have been in place since 1994, and they have been modified and updated regularly since. There are ten major evacuation routes (see map). The villages most at risk (inside the 12-kilometer radius “high risk” zone) include several in the states of Puebla (San Nicolás de los Ranchos, Santiago Xalitzintla, San Pedro Benito Juárez, San Baltazar Atlimeyaya and Tochimilco), Morelos (Ocuituco, Tetela del Volcán, Yecapixtla, Zacualpan de Amilpas and Temoac) and the State of México (Tepetlixpa, Ozumba, Atlautla, Ecatzingo and Amecameca).

Popocatepetl Volcano: the planned evacuation routes

Popocatepetl Volcano: the planned evacuation routes

Last week, the evacuation system (that will only be put into effect if the risk level rises) was tested with a large-scale practice evacuation in which the Mexican Army assisted municipal and state officials and emergency response crews. The practice has enabled authorities to improve the forecasts of precisely how long it will take to evacuate all villagers from the likely danger zone, in the event that the risk level is raised.

Evacuation will not be easy. Some local inhabitants argue that the volcano has never caused them any harm, because, on the contrary, it is their “protector and guide”. They are unlikely to move voluntarily even if an eruption is imminent. They hold a festival each year on 12 March thanking the volcano for its rich soil, abundant rainfall and “to keep the volcano calm and happy.” The ceremonies include the placing of offerings part-way up the volcano, accompanied by folk dancing.

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May is a critical month in the 2012 wildfire season in Mexico

 Mexico's geography in the Press  Comments Off on May is a critical month in the 2012 wildfire season in Mexico
May 032012
 

This month is likely to be a critical month for wildfires. As we reported in an  earlier post – The geography of wildfires in Mexico: the disastrous wildfire season of 2011 – 2011 was Mexico’s worst year for wildfires for 30 years. The on-going drought in northern Mexico (the worst for 70 years) means that this year’s wildfire season is not likely to be any better.

May is the critical month because it marks the end of the dry season in most of Mexico, the time when the natural landscape looks parched. During the month of May, the landscape waits for the start of the rainy season, a season that is sometimes preceded by a spate of electrical storms. Electrical storms can trigger wildfires if they ignite the tinder-dry vegetation.

In the first four months of 2012, there have been some significant wildfires in several parts of Mexico, including one uncomfortably close to the Guadalajara Metropolitan Area, which has a population of almost 5 million.

Here is a brief round-up of the major wildfires in 2012 so far:

Durango

The largest single fire in the country so far in 2012 was in Potrerillos, in the municipality of Canatlán. It damaged 112 square kilometers (43 square miles). The 56 other wildfires experienced by Durango so far this year have all been small. The total area of the state damaged by wildfires this year currently stands at about 120 square miles.

Coahuila
Coahuila has experienced 30 fires so far this year, causing to more than 160 square kilometers. The latest three fires have been brought under control in the past few days. In the Sierra Salsipuedes (municipality of San Buenaventura) a wildfire destroyed 8 square kilometers of brush. Wildfires in the Sierra de la Madera (in the municipalities of Ocampo and Cuatrociénegas) damaged 37 square kilometers and 17 square kilometers respectively.

Sonora

So far in 2012, firefighters have fought 19 wildfires, affecting almost 40 square kilometers it total, mainly grassland and scrub, in the municipalities
of Yécora, Álamos, Rosario Tesopaco, Bacoachi, Quiriego, Nacori Chico and Cucurpe.

Jalisco

Some 1,000 firefighters battled for almost a week to bring a major wildfire in the Primavera Forest (Bosque de la Primavera) under control. The Primavera Forest is a partially-forested wilderness area with hot springs. It is set in a volcanic caldera on the western outskirts of Guadalajara, Mexico’s second largest city.

Location of Primavera Forest in relation to Guadalajara and Lake Chapala.

Location of Primavera Forest in relation to Guadalajara. Credit: Tony Burton; all rights reserved.

Initial reports say that the blaze began on 14 April when a garbage fire got out of control. By the time it was brought under control, the fire had damaged 85 square kilometers, about 35% of it forested, making it the worst fire in the area since 2005. That area damaged is about one-third of the total area of the Primavera Forest. Residents of Guadalajara were luckier than in 2005 because winds this time blew most of the smoke away from the city, so the city’s air quality was not seriously compromised. Even so, schools in some areas were closed briefly as a precaution.

The Primavera has a chequered history of protection. Most of the land is privately owned. It was declared a federally protected area in 1980, but ever since then real estate developers have nibbled away at the edges of the protected area, largely ignoring attempts by local officials to enforce zoning regulations.

Morelos
Several relatively small fires have damaged parts of this small state. The three most significant wildfires to date were in the municipalities of Tepoztlán, Tlalnepantla and Tlayacapan. They damaged 5 square kilometers of forest, but, because of the precipitous terrain, required the combined efforts over four days of more than 700 firefighters. The area, very close to Mexico City, is a popular weekend destination for city dwellers, and renowned for its ecotourism potential. Tepoztlán is one of Mexico’s Magic Towns.

Puebla
A small fire in Cerro del Palmar (in Liebres municipality) unfortunately resulted in two deaths, including that of a firefighter.

Oaxaca
More than 30 square kilometers have been damaged by wildfire this year in various parts of the state.

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Apr 222012
 

Popocatepetl is Mexico’s second largest volcano, after El Pico de Orizaba. Popocatepetl rises to a height of 5500 meters (18,045 feet) and is located approximately mid-way between Mexico City, about 80 kilometers (50 miles) to the northwest, and the city of Puebla, a similar distance to the east.

In the past week, Popocatepetl (aka “Popo” or “Don Goyo”) has sprung back into life, blowing off steam and ash in a series of minor eruptions, accompanied by minor earth tremors, many of which registered between 3 and 4 on the Richter scale. Incandescent rocks (“volcanic bombs”) have been thrown up to 1000 meters (3000 feet) from the crater down the slopes of volcano, and water vapor, gasses and ash have formed towering clouds, up to 2000 meters high, rising above the iconic volcano.

Popocatapetl lets off steam. Credit: Victor Hugo Rojas (Universal)

Popocatepetl lets off steam. Credit: Victor Hugo Rojas (Universal)

The latest eruptions of Popocatepetl come from an estimated sixty different vents that are connected to a magma chamber 10 km (6 miles) beneath the volcano that is thought to hold upwards of 1,000,000 cubic meters (36,000,000 cubic feet) of magma. On the one hand, the small eruptions are good news, since they relieve the pressure building up underground, at least temporarily. On the other hand, they may presage a much more serious and major eruption.

Thousands of families live in the farming villages on the lower slopes of the volcano; some 25 million people live within a 100 kilometer (60 mile) radius. In the event of a major eruption, and depending on wind directions, airborne ash could fall on Mexico City, interrupting normal activities and Mexico City’s busy international airport, or on the Metropolitan area of Puebla (population 2.7 million), an important industrial center, where Volkswagen has its main vehicle factory.

Even though geophysicists are unable to say whether or when a major eruption will actually occur, authorities have raised the threat level and taken steps to ensure that local residents can be safely evacuated, if necessary, to emergency shelters in nearby public buildings such as schools. Almost 200 temporary shelters have been prepared in nearby villages to house any people that are forced to leave their homes.

Mexico’s National Disaster Prevention Centre (El Centro Nacional de Prevención de Desastres, Cenapred) has raised the alert level to “yellow stage three” – the third highest level. This level indicates that a magma expulsion is possible and that the intensity of explosions is likely to increase.

  • Access to latest CENAPRED report (in Spanish and English) English link is under “Reportes”

In the event that the alert is raised still further, into the red zone, villages within a 12-km zone will be immediately evacuated, and the exclusion zone may be extended still further if this is deemed a prudent safety measure. During the last major evacuation, in 2000, nearly 50,000 residents in three states were moved into temporary shelters.

As in the case of previous volcanic eruptions in Mexico, such as Paricutín in the 1940s, the Mexican Army would take charge of ensuring that local residents are taken to safety.

Roads are being kept open, and emergency repaving is underway, in case an evacuation is required. Local villages are arranging to have sufficient buses standing by to ensure that their residents can be evacuated rapidly should the alert level be raised. Even so, it is unlikely that everyone would choose to leave, and it is thought that up to half the population might attempt to remain in their homes even if the alert level is raised.

Images of the volcano:

Health authorities have already distributed free face masks and bottles of water to families in the area. The cloth face masks are intended to filter out the fine ash released by the volcano, and reduce the likely increase in respiratory problems. Falling ash is also expected to lead to an increased incidence of allergic conjunctivitis.

Authorities in the city of Puebla have temporarily suspended open air activities until further notice since much of the city has received a thin layer of ash. Ash falls of about one centimeter have been reported in some districts of the city. Ash has also fallen over the nearby town of Cholula and as far away as Atlixco and Huejotzingo.

Puebla hoteliers, restauranteurs and merchants will be hoping that the city’s restriction on open air activities ends quickly, since the city is gearing up for the annual festivities associated with the 5 de Mayo (5 May) festival for which the city is famous. (The festival commemorates Mexico’s victory over French forces at the Battle of Puebla on 5 May 1862).

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How has the movement of tectonic plates affected Mexico?

 Excerpts from Geo-Mexico  Comments Off on How has the movement of tectonic plates affected Mexico?
Apr 122012
 

In a previous post, we identified the tectonic plates that affect Mexico. In this piece, we look at some of the major impacts of Mexico lying on or close to so many different plates.

To the east of Mexico, in the last 100 million years, outward expansion from the Mid-Atlantic Ridge (a divergent boundary) first pushed South America ever further apart from Africa, and then (slightly more recently) forced the North American plate (and Mexico) away from Eurasia. The Atlantic Ocean continues to widen, expanding the separation between the New World and the Old World, by about 2.5 cm (1 in) each year.

Mexico's position in relation to tectonic plates

Mexico's position in relation to tectonic plates.Map: Geo-Mexico.com; all rights reserved

Meanwhile, to the west of Mexico, an analogous situation is occurring in the Pacific Ocean, where the Cocos plate is being forced eastwards away from the massive Pacific plate, again as a result of mid-ocean activity. The Cocos plate is effectively caught in a gigantic vice, its western edge being forced ever further eastwards while its leading eastern edge smacks into the North American plate.

The junction between the Cocos and North American plates is a classic example of a convergent plate boundary. The collision zone is marked by a deep ocean trench, variously known as the Middle America trench or the Acapulco trench. Off the coast of Chiapas, this trench is a staggering 6662 m (21,857 ft) deep. The trench is formed where the Cocos plate is forced to dive beneath the North American plate.

As the Cocos plate is subducted, its leading edge fractures, breaks and is partly re-melted into the surrounding mantle. Any cracks in the overlying North American plate are exploited by the molten magma, which is under immense pressure, and as the magma is forced to the surface, volcanoes form. The movement of the plates also gives rise to earthquakes. The depth of these earthquakes will vary with distance from the deep ocean trench. Those close to the trench will be relatively shallow, whereas those occurring further away from the trench (where the subducting plate is deeper) will have deeper points of origin.

As the plates move together, sediments, washed by erosion from the continent, collect in the continental shallows before being crushed upwards into fold mountains as the plates continue to come together. A line of fold mountains stretches almost continuously along the west coast of the Americas from the Rocky Mountains in Canada past the Western and Southern Sierra Madres in Mexico to the Andes in South America. Almost all Mexico’s major mountain ranges—including the Western Sierra Madre, the Eastern Sierra Madre and the Southern Sierra Madre—formed as a result of these processes during the Mesozoic Era, from 245 to 65 million years ago.

However, no sooner had they formed than another momentous event shook Mexico. About 65 million years ago, a giant iridium-rich asteroid slammed into the Gulf of Mexico, close to the Yucatán Peninsula, causing the Chicxulub Crater, and probably hastening the demise of the dinosaurs. An estimated 200,000 cubic km of crust was pulverized; most of it was thrown into the air. The resulting dust cloud is thought to have contributed to the extinction of up to 50% of all the species then on Earth. Not only did this event have an enormous impact on all life forms on Earth, it also left a legacy in the Yucatán. The impact crater is about 200 km (125 mi) across. Its outer edge is marked by a ring of sinkholes (locally known as cenotes) and springs where the fractured crust provided easy access to ground water. These locations include the ria (drowned river valley) of Celestún (now a UNESCO Biosphere Reserve), where fresh water springs mingle with salt water to create an especially rich habitat for birdlife.

In the 65 million years since the asteroid impact (the Cenozoic period), the remainder of Mexico has been formed, including many of the plateaus and plains, and the noteworthy Volcanic Axis, which owes its origin to still-on-going tectonic activity at the junction of the North American and Cocos plates.

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Two major earthquakes jolted western Mexico (11/12 April 2012)

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Apr 112012
 

Two major earthquakes in two days! Fortunately, they struck in different sections along Mexico’s west coast, meaning that few if any people were shaken by both. The first earthquake struck in Michoacán on 11 April, and was felt over a wide area of central Mexico. This earthquake registered 6.5 on the Richter scale (preliminary estimates had originally suggested it was magnitude 7.0).

The La Mira earthquake, Michoacán (source: USGS]:

  • Time: Wednesday, April 11, 2012 at 17:55 local time
  • Location 18.272N, 102.732̊W
  • Depth 20 km (12.4 miles)
  • The epicenter was about 61 km (38 miles) NW from Lázaro Cárdenas, Michoacán, 130 km (80 miles) SSW from Uruapan, Michoacán, and 143 km (88 miles) NW of Zihuatanejo, Guerrero. This placed it relatively close to the community of La Mira in the state of Michoacán.
  • Only minor damage was reported following this earthquake, despite its magnitude.

The Santa Isabel earthquake

The following day (12.15 am local time on 12 April), an even larger earthquake, magnitude 6.9, hit further north in Mexico, close to the coast of Baja California. Its epicenter was 183 kilometers (113 miles) from Santa Rosalia (Baja California Sur) and 214 kilometers (132 miles) from Hermosillo (Sonora). This meant that its effects were greatest in areas where population is very sparse (see map), and fortunately, once again, there were no reports of any loss of life or major damage.

Few people live in the region struck by the Santa Isabel earthquake.

Few people live in the region struck by the Santa Isabel earthquake.Credit: USGS

These two earthquakes come less than a month after the major magnitude 7.4 earthquake that hit the states of Oaxaca and Guerrero on 20 March 2012. This ‘quake caused significant damage – and was followed by dozens of aftershocks, including one on 2 April that registered 6.0 on the Richter scale.

Now that several parts of this junction of tectonic plates have shifted in quick succession, everyone hopes that these earthquakes will have relieved enough pent-up pressure, and re-adjusted the plates  sufficiently, to prevent further earthquakes in the region in the near future.

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Apr 092012
 

A recent report from researchers at the National Autonomous University of Mexico (UNAM) and the Metropolitan Autonomous University (UAM) confirms that the height of the water table below Mexico City is dropping by about one meter a year, as more water is pumped out of the aquifer than the natural replenishment rate from rainfall. About 60% of Mexico City’s drinking water comes from wells, with the remainder piped into the city, mainly via the Cutzamala system. The researchers say that up to 65% more water is taken from some parts of the Mexico City aquifer than the amount replaced each year by natural recharge.

As we reported in a previous post – Why are some parts of Mexico City sinking into the old lakebed? – this has resulted in parts of Mexico City sinking more than seven meters (23 ft) since 1891, with implications for water pipelines, drainage systems, building foundations and the city’s metro network, as well as an increased incidence of ground subsidence.

According to this latest research, the clay soil of the former lake bed below the city is sinking by between 6 and 28 cm/yr in most places, with rates in the southeast part of the city (where numerous wells have been drilled in recent years) sinking by up to 35 cm/yr.

How can the problem of sinking ground be resolved?

The report emphasizes the importance of conserving as much green space as possible within the city, to reduce runoff (and demands on the city’s drainage system) while simultaneously recharging aquifers. The three major alternatives, some combination of which is needed to resolve the problem are:

  • introduce more water-saving strategies so that demand does not continue to increase
  • bring more water from outside the Valley of Mexico (this would be costly and unpopular)
  • feed more wastewater back into the underground aquifers via “surface soaks”. As one example, the National Water Commission (Conagua) has announced plans to build a 200-million-dollar wastewater treatment plant (“El Caracol”) that will inject water back into the aquifer after treatment. It would be Mexico’s first ever large-scale reinjection project.

Perhaps not surprisingly, Mexico City residents pay more for their water than users anywhere else in the country, with an average water rate of US$1.23/cubic meter. Elsewhere, the two states sharing the arid Baja California Peninsula also have higher than average rates of $1.05/cubic meter (Baja California Sur) and $0.94/cubic meter (Baja California). The lowest rate in the country, well below the true cost of supplying water, is in Nayarit, and is just $0.25/cubic meter.

Within Mexico City, access to potable water is far from equally/fairly distributed across the city, as revealed by this thought-provoking quote :

In a study of water access in Mexico City, geographer Erik Swyngedouw found that “60 per cent of all urban potable water is distributed to three per cent of the households, whereas 50 per cent of the inhabitants make do on five per cent of the water”. Critical geographers like Swyngedouw ask us to take note of the spatial nature of power imbalances revealed in patterns of city design and growth: “mechanisms of exclusion… manifest the power relationships through which the geography of cities is shaped and transformed.”  [quote comes from page 31 of Nature’s Revenge: Reclaiming Sustainability in an Age of Corporate Globalization ; the reference is to Erik Swyngedouw’s Social Power and the Urbanization of Water: Flows of Power (OUP 2004).]

This grossly unequal distribution of potable water remains a critical problem that successive administrations in Mexico City and the surrounding State of México have done little to resolve.

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Which tectonic plates affect Mexico?

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Apr 022012
 

The theory of plate tectonics suggests that the earth’s crust or lithosphere is from 5 to 65 km (3 to 40 mi) thick and divided into about a dozen large tectonic plates, tabular blocks that drift across the Earth in different directions and at various speeds (up to a few centimeters or inches per year), probably as a result of thermal convection currents in the Earth’s molten mantle. Most plates consist of a combination of both ocean floor and continent, though some are entirely ocean floor.

Each tectonic plate is moving relative to other plates. The movements are not independent because the plates smash into and scrape against one another. Areas in the center of tectonic plates, far from the boundaries, have relatively little seismic activity, but the boundaries between plates are seismically very active, creating earthquakes and volcanoes. The level of seismic activity depends on the relative speed and direction of the plates at the boundary.

There are three distinct kinds of boundaries between plates. At divergent boundaries, along mid-ocean ridges, plates are being steadily pushed apart, with new crust being added by volcanic activity to the rear of each plate as it moves. At convergent boundaries, plates collide and parts of the plates either buckle or fracture or are subducted back down into the molten mantle. The third kind of boundary is where plates are neither created nor destroyed but are moving side by side. The resulting friction as they rub against each other can produce large earthquakes.

Almost all of Mexico sits atop the south-west corner of the massive North American plate (see map). Immediately to the south is the much smaller Caribbean plate. The North American plate extends westwards from the Mid-Atlantic Ridge, which runs through Iceland and down the middle of the Atlantic Ocean, to the western edge of North America. In a north-south direction, it extends from close to the North Pole as far south as the Caribbean.

Mexico's position in relation to tectonic plates

Mexico's position in relation to tectonic plates.Map: Geo-Mexico.com; all rights reserved

While most of Mexico rests on the North American plate, it is also influenced by several other plates.

The Baja California Peninsula is on the gigantic Pacific plate, which is moving northwest and under the North American plate. The intersection of these plates under the Gulf of California causes parallel faults which are part of the famous San Andreas Fault system. Thus, the Gulf of California is an area of heavy seismic activity.

The small Rivera plate, between Puerto Vallarta and the southern tip of Baja California, is moving in a southeasterly direction and rubbing against the Pacific plate; it, too, is moving under the North American plate.

The Cocos plate and tiny Orozco plate are ocean crust plates located off the south coast of Mexico. The collision of the Cocos plate and the North American plate has had several far-reaching consequences, including both the disastrous 1985 earthquakes that caused such severe loss of life and damage in Mexico City and the much more recent 2012 earthquake that, fortunately, was far less destructive.

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Major earthquake strikes Guerrero and Oaxaca states (20 March 2011)

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Mar 202012
 

Given its strength (almost the same as the 1985 Mexico City earthquake), this latest earthquake could have been so much worse… but it appears that central Mexico escaped with only relatively minor damage.

The earthquake happened 12:02 p.m. local time at a depth of about 10 km (6 miles), some 200 km (120 mi) east of the resort city and was felt as far away as Mexico City. The epicenter was close to the settlement of Ometepec, roughly midway between Acapulco and Oaxaca City.

The USGS originally recorded the earthquake as a 7.6, but has since downgraded the magnitude to 7.4.

Mexican sources say the earthquake lasted 2-3 minutes. Several significant aftershocks have been recorded since. The shaking was felt in Guerrero, Morelos, Puebla, Tlaxcala, Estado de Mexico, the Federal District and as far as Veracruz.

Main impacts reported so far:

  • No deaths have yet been reported, but 7 people were injured as a direct result of the earthquake. Perhaps the luckiest to survive was the driver whose vehicle was crushed by debris when part of a pedestrian overpass collapsed (see image):
  • 800 houses, in several municipalities, are reported damaged. The major damage is in the Costa Chica region of Guerrero. The municipalities affected include Ometepec, Tlacoachistlahuaca, Xochistlahuaca, Cuajinicuilapa, Igualapa, Azoyú and San Luis Acatlán.
  • Personnel from Mexico’s armed services have established temporary shelters to house those that lost homes or who are considered at risk from aftershocks. Many families have opted not to return to their homes to sleep, fearing further quakes.
  • 2.5 million people, mainly in central Mexico, lost electricity, but most had their power restored within hours.
  • The earthquake triggered several small landslides on highways in Oaxaca. In addition, traffic flow was briefly interrupted on the Acapulco-Cuernavaca highway, at kilometer 251.
  • Telephone service (including cell phone service) was briefly interrupted in several areas, while technicians carried out safety checks. Ay one point, more than 40,000 technicians were on standby.
  • Water provision. The Chalco-Xochimilco aqueduct was damaged, affecting about 100,000 people who live in the Tláhuac district of Mexico City. Elsewhere, 200,000 residents of the Iztapalapa district had their water supply interrupted due to damage to the La Caldera aqueduct. In both cases, repairs are expected to be completed within 48 hours.
  • School classes were suspended for the afternoon session in several places, including Acapulco, Igualapa, Cuajinicuilapa, Xochistlahuaca, Azuoyú, San Luis Zacatlán andOmetepec, and in Oaxaca City.
  • In Mexico City, the seismic alarm system functioned and gave residents a few seconds warning before the quake struck. In the words of one Twitter user (@RodrigoEBR) “FOR THE RECORD: The Mexico City earthquake early warning system was activated just seconds before the 7.6 quake”.
  • Shares in Cemex, Mexico’s multinational cement manufacturer, rose almost 4% on the day in late trading, as speculators bet on increased demand for cement and construction materials in the wake of the earthquake.

The USGS collects first-hand reports to map intensity:

  • Acapulco earthquake intensity map [maps tab]

This is the the intensity map several hours after the event:

Earthquake update [28 March 2012]

According to the latest press reports, more than 32,000 homes and 1,057 schools in the states of Oaxaca and Guerrero sustained some damage as a result of the 20 March 2012 earthquake. This figure includes 30 schools in the Costa Chica region of Guerrero that will need to be completely demolished and rebuilt from scratch.

As of 26 March the area had experienced more than 200 aftershocks of Richter scale 3 or greater.

The insurance industry expects claims from the earthqauke to reach about 5.6 billion pesos [about US $ 440 million], with most claims expected from policy holders living in the Guerrero, Oaxaca, the Federal District, Puebla and Morelos.

Damage to Line A of Mexico City's metro following 20 March 2012 earthquake

Damage to Mexico City metro Line A after 20 March 2012 earthquake

Damage in Mexico City included a section of line A of the city’s metro network (see image), where 100 meters of track between Santa Martha and Acatitla stations were buckled and have now been replaced.

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The geography of wildfires in Mexico: the disastrous wildfire season of 2011

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Jan 212012
 

In the past 20 years, wildfires have destroyed 47,000 square kilometers (18,000 sq. mi) in Mexico, equivalent to five times the area of all sections of Mexico City’s Chapultepec Park, the largest urban park in Latin America. The average fire in Mexico affects 32 hectares (80 acres); this figure has not changed significantly in recent years, even though the incidence of fires has increased somewhat due to a combination of climate change and an increase in the number of people living on the margins of forested areas. The National Forestry Commission (Conafor) says that 99% of Mexico’s forest fires are caused by human error, and only 1% are due to natural causes such as lightning strikes.

It generally takes about 30 years to rehabilitate forest areas ravaged by fire, with reforestation costing up to $2400/ha.

Wildfires are not entirely bad. For example, they help regenerate grassland areas, especially, with fresh young plants. On the other hand, in addition to protecting the existing vegetation, stopping wildfires when they occur helps to preserve soil structure and prevents additional emissions of CO2 from the burning of more plant material. At a national level, it is estimated that fires result in the erosion of 86 million metric tons of soil a year.

In a 2009 study, Conafor used 17 variables to identify the areas of the county with the highest risk of wildfires. Three broad areas accounted for the 900,000 square kilometers identified as having either a “medium” or “high risk” for wildfires:

  • i. Yucatán Peninsula, Chiapas, Oaxaca and Guerrero
  • ii. Central Mexico – Veracruz, Tlaxcala, Puebla, México, Michoacán, Jalisco and the Federal District. This area has more fires than any other because local populations often use fire to clear fields before planting.
  • iii. Baja California. This is the only area where the main fire season is in summer, from March to November. This is the rainy season in the remainder of Mexico, where the fire season corresponds with the winter dry season.

The first half of 2011 was an especially bad period for wildfires in Mexico, the worst for at least 30 years.

Coahuila wildfire, April 9, 2011 (Earth Observatory, Landsat-5)

Coahuila wildfire, April 9, 2011 (Earth Observatory, Landsat-5)

During the first half of 2011, serious wildfires devastated several areas of northern Mexico, with the states of Coahuila and Nuevo León being hardest hit. Other states badly affected included Durango, Chihuahua, Quintana Roo, Oaxaca, Puebla and Guerrero. More than 7,800 fires occurred, severely damaging a total area of 4100 square kilometers. 30 of Mexico’s 32 states were affected; only Tabasco and Baja California Sur escaped unscathed.

Conafor’s annual fire-fighting budget for the entire country is only 650 million pesos ($50 million dollars); the average annual area damaged by wildfires is only 2600 square kilometers, of which 500 square kilometers are forest. At the height of the 2011 fire season, more than 60 new fires were being reported each day, according to Conafor.

Coahuila

In the state of Coahuila, fires damaged 250 square kilometers in four weeks. It is believed that 50% of these fires were due to farmers losing control of deliberate burns. Farmers are supposed to have an adequate fire-suppression plan in place before setting a deliberate burn, but in practice this requirement is not enforced.

The main locations were La Sabina and El Bonito. Authorities were very slow to respond. Diana Doan-Crider, a wildlife biologist at Texas A&M University, has spent the past 25 years studying the Mexican black bear in the Serranía del Burro in Coahuila, an ecological corridor that runs parallel to the Eastern Sierra Madre. The area includes a large population of Mexican black bears. Doan-Crider claims that authorities completely ignored the first warnings and that their eventual response (two weeks after the first fires started) lacked adequate coordination. Many mother bears and their young cubs perished in the fires.

Firefighters in Coahuila had to cope with a spectacular but terrifying fire whorl or fire tornado

Nuevo León

In the neighboring state of Nuevo León, large swathes of ranching land were ravaged by fire. One rancher who lost more than 10,000 ha of cattleland was equally critical of the slow response time of firefighters who took more than two weeks to appear on the scene, by which time the fires had taken hold.

David Garza Lagüera had converted his 14,000 ha ranch into the Cumbres de Monterrey National Park, one of the key areas of bear habitat. The largest pines on his land were more than 150 years old. All were totally destroyed.

The worst damage was in Galeana, Montemorelos, Zaragoza, Aramberri and Mina. The area burned in Nuevo León in May 2011 was almost ten times the total area affected in the state for the whole of 2010.

Why was the 2011 fire season so bad?

To quote the Earth Observatory, “Lack of winter rain and frost left the plants dry and prone to fire. On top of that, the area has not burned for more than 20 years, during which time fuel built up. Thunderstorms and steady strong winds with gusts up to 110 km/h (70 mph) completed the formula for a dangerous, fast-moving wildfire.”

Ironically, the passage of Hurricane Alex in July 2010, which brought 1500 mm (60″) of rain to the Serranía del Burro, actually worsened the fire damage the following year. The rain from Hurricane Alex encouraged so much new growth in the final months of the rainy season that when it died back in the dry season, there was far more fuel available than usual for any wildfire that was sparked.

By the time the federal government declared a state of emergency, it was too late; the fires had already destroyed large areas of grassland, scrubland and forest. The emergency response when it finally arrived included help from the USA and Canada such as the specialist aerial Mars water-bombers stationed on Vancouver Island. The fires were only fully extinguished once the annual rainy season arrived.

As we now know, the disastrous fires of April-May 2011 were an early sign of Mexico’s worst drought for 70 years:

How accurate was last year’s hurricane prediction?

 Other  Comments Off on How accurate was last year’s hurricane prediction?
Jan 162012
 

The annual prediction of the hurricane activity on the Atlantic/Gulf/Caribbean side of Mexico for 2011 by Dr Philip Klotzbach and Dr. William Gray (Colorado State University) was for a slightly more active season than in 2010. For 2011, they introduced some modifications to their predictive model, which now takes into account:

  • Predictor 1. Gradient of sea surface temperatures (SST) in February-March between the Eastern Subtropical region of the Atlantic and the South Atlantic. This has a positive connection with hurricane activity.
  • Predictor 2. Air pressure at sea level in March in the Subtropical Atlantic. This has a negative connection with hurricane activity.
  • Predictor 3. Air pressure at sea level in February in the South-Eastern Pacific. This new variable has a positive connection with hurricane activity.
  • Predictor 4. Forecast made in March from Central Europe for sea surface temperatures in September for the El Niño-3 region. This new predictor has a negative connection with hurricane activity.
Tracks of Atlantic Hurricanes, 2011

Tracks of Atlantic Hurricanes, 2011

In April, the prediction for the 2011 Atlantic/Caribbean hurricane season was for 16 tropical cyclones, including 7 tropical storms, 4 moderate hurricanes (Category 1 or 2 on the Saffir-Simpson scale) and 5 strong hurricanes (C 3, 4 or 5).

This prediction proved to be quite good. In the event, there were actually 19 tropical cyclones, including 12 tropical storms, 4 moderate hurricanes (C1, C2) and 3 strong hurricanes (one C3 and two C4).

Tracks of Pacific Hurricanes, 2011

Tracks of Pacific Hurricanes, 2011

On the Pacific coast, the 2011 season saw 11 tropical cyclones including 1 tropical storm, 4 moderate hurricanes and 6 strong hurricanes. Fortunately, almost all these cyclones remained out at sea and only Hurricane Jova, which reached category 3 in early October, caused any significant damage on land (see Hurricane Jova smashes into Barra de Navidad and Melaque on Mexico’s Pacific Coast).

Want to read more?

Related posts:

Mexico’s 2011 drought is raising the price of basic foodstuffs

 Mexico's geography in the Press  Comments Off on Mexico’s 2011 drought is raising the price of basic foodstuffs
Dec 052011
 

This year’s drought – see Many states in Mexico badly affected by drought is now widely viewed as the worst to occur since modern record-keeping for precipitation began about 80 years ago.

Short-term droughts are not unusual in Mexico. As the graph shows, there is a clear cyclical pattern to the timing of short-term droughts in Mexico. This is because most of the country receives almost all its annual precipitation in just a few months, from May or June (depending on precise location) to September-October.

The scale of the current drought is readily apparent from the graph. This year, far more of the country is affected, and the level of drought is far more severe.

Seasonal drought in Mexico, 2003-2012
Seasonal drought in Mexico, 2003-2012. Click to enlarge.

The drought is having numerous adverse impacts

It is already having an effect on food prices. Several of the basic foodstuffs  making up Mexico’s basic basket of goods for economic indices such as the inflation index, have risen sharply in price in recent months. A shortage of corn has led to a 70% increase in imports of yellow corn from the USA.

Incredibly, Mexico, the home of corn, is now the world’s second largest importer. Corn, as we have noted in previous posts, is a vital ingredient in Mexican cuisine, and is particularly important in the southern half of the country, especially in the more rural and indigenous areas. The shortage of corn has led to a rise in the price of tortillas, a dietary staple in almost all of the country. Tortilla prices have risen up to 18%, many times Mexico’s overall inflation rate of about 3.5%.

The production of chiles, another staple of the Mexican diet, has also fallen due to the drought, by an estimated 40%. In Zacatecas, that state’s 2,500 chile-growers will have produced 120,000 tons of green chile and 62,150 tons of dried chile this year, even though they have only been able to harvest chiles twice this year, rather than the normal four times. The state is the leading source of dried chile in Mexico. The area cultivated for chiles in Zacatecas has also fallen this year, to 31,300 hectares. The decrease in production has had a direct impact on the number of harvesting jobs available, since each hectare of chile cultivation usually means 150 seasonal jobs. The production shortage for chiles will be offset by more imports from Peru and China.

At latest count, 770 municipalities are now suffering from drought, and at least 2.5 million people in 1500 communities are left with insufficient drinking water. In the state of Durango alone, more than one million people are currently experiencing extreme drought, and 149 communities are completely without drinking water.

The long-term outlook is not favorable for these areas since climate change is expected to increase both the frequency and severity of droughts over the next twenty to thirty years.

Related posts:

Unusual hazard: gasoline pours out of storm drains in Poza Rica, Veracruz

 Mexico's geography in the Press  Comments Off on Unusual hazard: gasoline pours out of storm drains in Poza Rica, Veracruz
Nov 262011
 

Recent floods in parts of the city of Poza Rica (Veracruz) resulted in an unusually dangerous situation. As groundwater rose following exceptionally heavy rains, a mixture of water and oil flowed out of some street drains.

street awash with oil photo

A Poza Rica street awash with oil and water. Credit: La Voz del Sureste

The precise cause is unknown. The city is blaming the state oil giant Petroleos Mexicanos (Pemex). Pemex claims that the hydrocarbons are natural tar, deposits of which underlie some parts of the region.

Whatever the cause, the flooding resulted in extremely hazardous conditions in the Chapultepec colonia, where Ébano, Nogal, Chopo, Eucalipto, Ciprés, Fresno and Sabino streets were badly affecfed, and in the Cazones colonia, where the aptly-named Pozo 13 (Well 13) was awash with oil. The mayor of Poza Rica was quoted as saying that “The rivers of crude left parked cars completely covered.”

Families living in the affected areas were evacuated temporarily for their own safety. Fortunately, local authorities, assisted by Environmental Protection officials and Pemex experts, were able to quickly bring the situation under control, without any loss of life or serious injuries.

Sources:

  • Brota hidrocarburo de drenajes en Poza Rica (Diario La Voz del Sureste online)
  • Concluyen limpieza de derrame de hidrocarburo en Poza Rica (xeu.com.mx)

 

Many states in Mexico badly affected by drought

 Mexico's geography in the Press, Updates to Geo-Mexico  Comments Off on Many states in Mexico badly affected by drought
Nov 232011
 

Much of Mexico is currently affected by some degree of drought (see map below). The National Meteorological Service (SMN) reports that September was one of the driest months in some 70 years. All the signs suggest this is the worst year for drought since 1941. The worst affected states are Sonora, Chihuahua, Coahuila, Durango, Nuevo León and Zacatecas. (Paradoxically, some parts of southern Mexico, especially in the states of Oaxaca and Tabasco, have experienced serious flooding in recent months).

In the drought zones, emergency programs are getting underway to provide temporary work for many rural dwellers and to supply potable water to the worst affected settlements. In addition to crop losses, up to one million head of cattle will have been put down by year-end in northern states as a direct result of the drought, since farmers do not have sufficient fodder available to feed them as usual.

While some cattle have been exported to the USA, local meat prices will be driven down by the increase in supply, making many farmer’s livelihoods even more precarious. Many farmers will need federal assistance to overcome this latest crisis.
Areas suffering from drought, October 2011

Areas suffering from short-term and long-term drought, October 2011. Click map to enlarge

Durango faces the worst drought for 100 years

In Durango, water has been provided to 32,691 residents in 10 municipalities, with another 36 municipalities to be supplied in the current phase of emergency assistance. Officials in Durango say it is the state’s worst drought for 100 years, with most larger reservoirs in the state now holding between 20% and 40% of their capacity; one reservoir is already down to less than 10% of its.

Irregular rains over the past few months have done little to replenish reservoirs, leaving farmers in despair. The long-range forecast does not appear to offer them much consolation, with the drought expected to last well into next year.

By mid-September, some parts of Durango had received less than 140 mm of precipitation so far ths year, well below the 425 mm registered for the same period in 2010.  The only hope for local farmers appears to be if late season hurricanes bring far more rain than expected to this region.

The drought news from other states

In Chihuahua, 589 tankers have delivered water to settlements housing 62,000 in 15 different municipalities: Guazapares, Janos, Manuel Benavides, Morelos, Moris, Ocampo, Ojinaga, Urique, Uruachi, Aldama, Balleza, Bocoyna, Guachochi, Guadalupe and Calvo.

In Zacatecas, a “state of emergency” has been declared for 52 of the state’s 58 municipalities. More than 150 communities are seriously affected, especially smaller communities in the municipalities of Fresnillo, Jerez, Guadalupe, Tlaltenango, Nochistlán, Atolinga, Villa de Cos, Genaro Codina and Teúl de Gonzalez Ortega.

Drought has affected 288,000 hectares of rain-fed crops in Guanajuato. The greatest losses are of corn, beans, wheat, sorghum and other grains, with the worst-hit areas located in the northern part of the state. More than a million liters of potable water have been supplied to 18,000 inhabitants living in 133 settlements in the state, located in the municipalities of Atarjea, Doctor Mora, San Diego de la Unión, San Felipe, Santa Catarina, Tierra Blanca, Victoria and Xichú.

Horticulturalists in Sinaloa growing vegetables, grains and fruit for export want 30 million dollars in emergency funds to restore irrigation to 700,000 hectares of productive land. More than 200,000 seasonal jobs are at risk.

Related post:

Mexico’s water resources and water-related issues are the subject of chapters 6 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy…

 

Mexico, USA and Canada cooperate to produce monthly drought maps

 Books and resources  Comments Off on Mexico, USA and Canada cooperate to produce monthly drought maps
Nov 192011
 

The North America Drought Monitor (NADM) is a “cooperative effort between drought experts in Canada, Mexico and the United States to monitor drought across the continent on an ongoing basis”. The program began  in 2002 . The NADM is an extension of an earlier version that was limited to the USA.

The NADM combines multiple indices and local information to produce “drought monitor” maps that best reflect the consensus of numerous scientists, some working at state or federal level, and others working in tertiary education and research.

What exactly is a “drought”?

The basic definition of a drought is a prolonged period of abnormally low precipitation. In practice, this means a period when precipitation is significantly less than would normally be expected for the time period under consideration. The amount of precipitation that is “normal” varies greatly from one area to another, and can also vary with the seasons. Low precipitation in a desert would not necessarily indicate a drought! On the other hand, low precipitation in a rainforest almost certainly would indicate a drought. Since most of Mexico experiences a dry season and a rainy season each year, this further complicates the picture. Not only is it important to know how much precipitation falls, but it is also important to know when it falls.

Areas suffering from drought, October 2011
Areas suffering from short-term and long-term drought, October 2011. Click map to enlarge

This definition must be borne in mind when looking at the Drought Monitor maps, as should the seasonality of precipitation throughout most of Mexico, and the distribution of precipitation, which varies greatly from north to south.

The NADM maps show that the drought situation can change quite rapidly from one month to the next. (Use the link above to compare February and March 2011, for example, or March and April 2011).

In a future post, we will take a closer look at the impacts of the drought (shown on the map) that currently affects much of northern Mexico.

Hurricane Jova smashes into Barra de Navidad and Melaque on Mexico’s Pacific Coast

 Mexico's geography in the Press  Comments Off on Hurricane Jova smashes into Barra de Navidad and Melaque on Mexico’s Pacific Coast
Oct 142011
 

The twin coastal towns of Melaque and Barra de Navidad in the state of Jalisco felt the full force of Hurricane Jova earlier this week. Barra de Navidad has great historical importance as one of the shipbuilding ports where the Spanish built the ships which traversed the Pacific Ocean to the islands of the Philippines.

Full details are only beginning to emerge of the damage done, but the following links show the storm’s path, and some of its immediate impacts:

Fortunately, Hurricane Jova had lost some of its strength by the time it slammed into the coast as a Category 2 hurricane on 12 October. It had previously packed winds of up to 160 km/hr. Even so, it brought torrential rain to coastal areas between the major resorts of Puerto Vallarta and Manzanillo, and heavy rain inland as far as Guadalajara (about 400 km from the coast). In Guadalajara, the flag-raising ceremony to mark the start of the 2011 Pan-American Games was postponed by a day because of continuous rainfall.

In Puerto Vallarta, where several Pan-American Games events are scheduled to be held, including sailing, triathlon, beach volleyball, and open water swimming, authorities secured boats and reinforced the beach volleyball courts with sandbags.

The catastrophe-modelling firm AIR Worldwide says Hurricane Jova will have caused less than $52m of damage as it hit a sparsely populated stretch of Mexico’s Pacific coast downgraded as a Category 2 hurricane.

Many smaller settlements, including Cihuatlán, La Huerta, Villa Purificacion, and Cuautitlán de García Barragán were temporarily cut off as floodwaters made the main coastal highway impassible. Streets in many towns were inundated.

Details of the storm’s track and intensity will (in due course) be available at the National Hurricane Center’s archive for 2011 Eastern Pacific Hurricanes.

Previous hurricane-related posts include:

Hurricanes and other climatological phenomena are analyzed in chapters 4 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, so you have a handy reference guide available whenever you need it.

Examples of high risk settlements located near Pemex pipelines

 Mexico's geography in the Press  Comments Off on Examples of high risk settlements located near Pemex pipelines
Sep 292011
 

There have been several fatalities associated with Pemex pipeline explosions in recent years, sometimes resulting from illegal attempts to tap into the lines. They include the disastrous blast in San Martin Texmelucan, Puebla, in December 2010 that killed 28 people. It therefore comes as something of a surprise to find press reports highlighting areas where people continue to live in vulnerable locations exposed to unacceptably high risks. In this post, we look at three examples, from the states of Oaxaca, Veracruz and Hidalgo respectively.

According to a report by Martha Izquierdo in Mexico City daily Reforma, more than 300 families in the industrial port of Salina Cruz (Oaxaca) live in homes sitting atop Pemex pipelines.

Previous municipal administrations are alleged to have issued permits for their construction, in total disregard for the potential dangers involved. The current municipal and state authorities have no plans to relocate these families, despite the daily risk they face. The pipelines carry oil into Pemex’s Salina Cruz refinery.

Pemex pipeline danger sign
Pemex pipeline warning sign. Credit Revista Buzos

The areas at risk are in the Deportiva, Hugo Mayoral, San Pablo Norte and San Pablo Sur districts (colonias) of Salina Cruz. Besides the homes, there are also vehicle repair shops, restaurants and even a shopping center in the zone along the pipelines.

In Coatzacoalcos, Veracruz, near another Pemex refinery called Pajaritos, a small town called Mundo Nuevo has sprung up to house construction and refinery workers. Its 20,000 residents live in close proximity to no fewer than 26 pipelines entering and leaving the refinery and, according to this report from  Jesús Lastra Ríos, they are not even certain of what materials are being carried in the pipelines, let alone their toxicity, flammability and explosiveness. In this case, apparently, the state “risk atlas” includes details of the pipeline diameters, but not their contents.

Clearly, settlements of any kind should not be allowed so close to Pemex pipelines, but there are many similar instances in Veracruz, as there are in many other states.

In Hidalgo state recently, the Education Ministry identified three schools as having been built “in high-risk areas near Pemex pipelines”. The state is making emergency plans to relocate the schools at an estimated cost of around $5 million. The schools are in the municipalities of Villa de Tezontepec, Ajacuba and Tlaxcoapan. The Hidalgo state government has a “risk atlas” covering landslide and other risks, but, apparently, most existing maps are based mainly on events that have already occurred.

These three examples serve to illustrate the seriousness of the situation in many parts of Mexico where planning restrictions have not been effectively enforced, and where risk assessments permitting accurate mapping of the most vulnerable areas have still not been completed and are therefore not available to municipal or state authorities.

Related posts:

To read more about the geography of hazards in Mexico, use the “Hazards” tag: http://geo-mexico.com/?tag=hazards

Natural hazards in Mexico are discussed in detail in chapters 2, 4 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico.

Driving in Mexico: is it safe relative to other countries?

 Books and resources  Comments Off on Driving in Mexico: is it safe relative to other countries?
Jul 282011
 

About 24,000 people were killed last year in traffic accidents in Mexico according to Ángel Martínez, Director of the Mexican Traffic Safety Research Center (Spanish acronym CESVI) . In the USA, the number was about 33,000 in 2010. Does this mean that is safer to drive in Mexico than the USA?

The simple answer is “no” because the USA has three times as many people, about ten times as many registered vehicles, and probably drives over ten times as many vehicle-miles as Mexico. Comparing traffic deaths among countries is relatively complicated because the data are often lacking or not comparable.

A large 2009 World Health Organization (WHO) study indicates that traffic deaths are related to numerous factors. Obviously, the number, age, condition and mix of motor vehicles are very important. Two-wheeled motor vehicles can be more dangerous than automobiles, buses or trucks. Furthermore, road quality, traffic infrastructure, laws, and enforcement are major factors. Many countries do not require use of seat belts, helmets or child seats. The training, skill level and behavior of drivers, as well as pedestrians, are also important. Other factors are alcohol use by drivers and pedestrians, as well as the quality and efficiency of emergency medical teams and health care systems.

50-vehicle pile-up in fog, Saltillo, January 2011

50-vehicle pile-up in fog, Saltillo, January 2011

According to the WHO study, Mexico ranked 12th in the world in total traffic fatalities. China ranked first with 221,000 deaths per year, followed by India, Nigeria, Pakistan, Indonesia, Russia, Brazil, USA, Egypt, Ethiopia, Iran and then Mexico. Total deaths are related to population, number of vehicles and pedestrians, poor traffic control and emergency medical systems, as well as crowded roads shared by everything from trucks, buses, cars and motor bikes to livestock and pedestrians.

Mexico has about 21 traffic deaths per year per 100,000 population. This is a fairer way to compare countries. On this statistic, Mexico does slightly worse than Brazil (18), China (17), India (17), Indonesia (16), and Thailand (20). Though Mexico is slightly better than Peru (22), Venezuela (22), Russia (25), and Pakistan (25), considerable improvement is needed. President Calderón has set as a goal of reducing traffic deaths by 50% by 2020. Mexico is significantly behind some of the other Western Hemisphere countries such as Canada (9), USA (11), Argentina (14), Colombia (17) and even Guatemala (15).

The major countries with the safest traffic are Japan (5), UK (5), Germany (6), and France (8). The least safe countries are mostly in Africa and include Egypt (42), Ethiopia (35), Kenya (34), Nigeria (32), the Congo (32) and South Africa (33).

Wear your seat belt and drive safely!

More problems for residents of Valle de Chalco on the south-eastern edge of Mexico City

 Mexico's geography in the Press  Comments Off on More problems for residents of Valle de Chalco on the south-eastern edge of Mexico City
May 112011
 

More than 200 homes in the low-income settlement of Valle de Chalco on the south-eastern edge of Mexico City, in the State of México, were flooded by raw sewage last month. The affected homes were in San Isidro and La Providencia, in Valle de Chalco (see map).

Mexico City cracks map
Locations in Valley of Mexico with high incidence of ground cracks. Cartography: Tony Burton; all rights reserved.

At least 500 residents faced a grim clean-up following several days of flooding. The problem was caused by a 30-meter-long crack in a surface sewage canal known as the Canal de la Compañia. The crack allowed 6,000 cubic meters a second of raw sewage to inundate nearby streets and homes. The federal water authority, Conagua, said that it would take three weeks to complete repairs to the canal wall.

Canal de la Compañia, Chimalhuacán

Canal de la Compañia, Chimalhuacán

The canal wall is thought to have been put under too much pressure due to the unfortunate combination of unusually heavy rains and a blockage occasioned by accumulated garbage such as plastic bags. It is possible that continued ground settling –More ground cracks appearing in Mexico City and the Valley of Mexico – also contributed to the problem. José Luis Luege Tamargo, the head of Conagua, placed much of the blame for the most recent flooding on the local municipal authorities of Ixtapaluca for not having ensured that no garbage was dumped anywhere in or near the Canal.

The 260 families and small businesses affected were all given some immediate financial assistance via 20,000-peso payment cards valid at any Soriano supermarket. In addition, authorities have pumped out basements and begun an emergency vaccination campaign.

The Canal de la Comañia’s walls have failed three times in the past decade, with serious flooding each time; the most recent disaster was in February 2010, when 18,000 people were forced to flee the rising wastewater. Conagua has reportedly proposed a more permanent remedy involving the rerouting of 7 km (almost 5 miles) of canal. The project would take two years to complete, with an estimated cost of 300 million pesos ($25 million).

How do El Niño events affect Mexico?

 Excerpts from Geo-Mexico  Comments Off on How do El Niño events affect Mexico?
Apr 112011
 

La Niña and El Niño are two major periodic disturbances to the normal oceanic and atmospheric circulation patterns over the Pacific Ocean which have widespread effects around the world. The normal circulation in the equatorial Pacific (the Walker circulation cell) results from a low pressure area over the western Pacific (due to warm surface ocean temperatures) and a high pressure area over the eastern Pacific (due to the upwelling of cold ocean water off the coast of Ecuador). Surface trade winds blow from east to west, while high altitude air flow is from west to east.

A La Niña event is an intensification of the normal Walker cell. This results in warmer and drier conditions than normal, rarely with serious consequences for Mexico.

However, during an El Niño Southern Oscillation (ENSO) event, the Walker circulation pattern is essentially reversed. Early in the year, warm ocean water extends much further east, causing warm moist air to rise off the coast of South and Central America, bringing heavy rainfall to areas along the west coast of Mexico. The El Niño in 1998 raised the temperature of water off Mexico’s Pacific coast by some 3° to 5°C (6° to 9°F) and also increased the humidity considerably. Historically, ENSO events have occurred every four to seven years, but their frequency may now be increasing.

The effects of an ENSO event are also felt on the Gulf coast. The low pressure area resulting from the air rising off the western coast causes air from further east to be dragged across Mexico. This means that more cold fronts or nortes enter north and central Mexico. Winter precipitation in these areas increases significantly, especially in the north, and temperatures are much cooler than usual. Flooding can result in coastal areas. ENSO effects are also felt in other parts of the world.

In Mexico, ENSO events not only affect winter precipitation but also summer precipitation, which is more critical for farmers. This is because they push the equatorial Intertropical Convergence Zone (ITCZ), where the north-east and south-east trade winds meet, further south. This reduces the convective activity and rainfall in Mexico’s central highlands. Furthermore, this may reduce cloud cover and therefore increase solar radiation and evapotranspiration, making the ground even drier.

In summary, subsistence corn (maize) farmers find that their cooler, wetter winter than normal is immediately followed by a hotter and drier summer growing season. This can have disastrous consequences for their food security. The rapid onset of changed conditions does not allow much time for adequate adjustments to be made to their choice of crops or farming methods.

Historical analysis combined with greater climatological understanding shows that many of the worst droughts and floods in Mexico have been associated with either ENSO events or with the related Pacific-North American Oscillation. Perhaps 65% of the variability of Mexican climate results from changes in these large-scale circulations.

The naughty nortes of Mexico

 Excerpts from Geo-Mexico  Comments Off on The naughty nortes of Mexico
Mar 292011
 

Mid-latitude storms known as nortes (northers) disturb the normal weather patterns up to 20 times a year during winter, from November to March. They occur when northern polar air moves south into northern and central Mexico.

They bring low pressure (cyclonic) conditions, heralded by the arrival of a cold front. The polar air displaces the warmer surface air, forcing it to rise as the cool air pushes its way underneath. At the surface, a sudden drop in temperature and the advent of cold winds marks the passage of the front, followed by several days of overcast skies with light rains or drizzle, onomatopoeically called chipichipis in some areas.

Rains from nortes are heavier on the northern or eastern sides of mountains where the cool air is forced to rise. As the front passes, the temperature can drop by 5–8 degrees C (9–14 degrees F) in a few hours.

From an agricultural perspective these rains are a welcome sight for farmers, helping to improve grazing land and reduce the chances of wind-blown soil erosion. However, the winds can play havoc with shipping in the Gulf of Mexico and result in ports being temporarily closed. Veracruz and Tampico are regularly affected.

Cold weather wreaks havoc on crops in Sinaloa, Mexico

 Mexico's geography in the Press  Comments Off on Cold weather wreaks havoc on crops in Sinaloa, Mexico
Feb 212011
 

Corn production has been the core of Mexican agriculture throughout its history, and continues to be very important. Production has increased by more than 40% since 2000. Currently corn is grown on about half of all agricultural land. However, corn is a rather low value crop and accounts for only about 14% of total crop value.

Corn, for both human and livestock consumption, is grown virtually everywhere in Mexico and is the leading crop in 17 of the 32 states. The leader in volume of corn produced is Sinaloa with 28% of the national total. Other major corn states are Jalisco (12%), State of Mexico (6%), Michoacán, Guanajuato and Guerrero (5% each).

The unusually cold weather in early February 2011 hit farming areas in northern Mexico particularly hard. Farmers in Sinaloa, the “Bread Basket of Mexico,” report that 300,000 hectares (750,000 acres) of corn were destroyed after unusually cold temperatures in the first few weeks of the year. A further 300,000 hectares suffered some damage. Sinaloa has 470,000 hectares of farmland devoted to the white corn used to make tortillas; 90% of this area has been damaged. Heriberto Felix Guerra, federal Secretary for Social Development (SEDESOL) called the weather-related losses the worst disaster in Sinaloa’s history. The economic loss could exceed three billion dollars.

The federal Agriculture Secretariat is rushing urgent aid to farmers, including tax breaks and low-interest loans for seed, in the hopes that many of them can replant their corn crop while there is still time. As of today, more than 130,000 hectares of corn in Sinaloa have already been replanted. The aim is to reseed between 200,000 and 300,000 ha (500,000-750,000 acres) of corn, for an eventual harvest (in Sinaloa) of 3 million metric tons of corn. The reseeding must be completed by 10 March as, after that date, there are too few “growing days” to guarantee a harvest. Average yields in Sinaloa for white corn are expected to fall from their usual 10 tons/ha to around 7 tons/ha this year.

Mexico has an annual shortfall in corn production and always has to import some corn (mainly from the USA and South Africa) to meet total domestic demand. This year, the government is considering raising its usual import quotas to ensure ample supplies of corn (and tortillas) for the coming year. Corn prices have already shot up; Mexico’s imports are going to cost a lot more than in recent years.

Citrus orchards, tomato crops and other vegetables were also decimated. Tomatoes are by far the most important horticultural crop in Sinaloa, but other crops affected include green beans, squash and chiles. It will be another 6 weeks to 2 months before another tomato harvest is possible. The price of tomatoes also rose immediately and could double, at least temporarily, within the next few weeks.

The Mexican tomato crop is mainly the larger Roma variety which is widely used in the fast food industry. Already at least one fast-food chain in the USA is adding tomato slices to hamburgers only on request; the smaller tomatoes used in salads are not affected by the recent cold snap.

Previous related posts:

More ground cracks appearing in Mexico City and the Valley of Mexico

 Mexico's geography in the Press  Comments Off on More ground cracks appearing in Mexico City and the Valley of Mexico
Jan 192011
 

The continued sinking of some parts of Mexico City in response to the over-extraction of water from underground aquifers, and consequent shrinking of the subsoil, has resulted in dozens of cracks in recent years. As noted in a previous post – Why are some parts of Mexico City sinking into the old lakebed? – some buildings in Mexico City have dropped more than seven meters (23 ft) since 1891.

According to Gabriel Auvinet Guichard, a researcher at the Engineering Institute of the National University (UNAM), cracks are becoming increasingly frequent. The largest cracks are up to 22 meters (72 feet) deep and 30 meters long. The cracks damage buildings and infrastructure (especially roads and water pipes), and have alarmed residents in some areas in the city.

Auvinet’s team at UNAM’s Geoinformatics Laboratory is compiling a database of all known cracks. They plan to produce maps showing the incidence, location and origin of the cracks to help construction companies meet building regulations. The database has records of 380 fissures at present, but is still far from complete.

Some areas in the Valley of Mexico are much more prone to the earth movements leading to cracks than others. The areas with a high incidence of cracks include Iztapalapa, Chalco, Xochimilco, Xalostoc and Vallejo (see map).

Mexico City cracks map

Locations in Valley of Mexico with high incidence of ground cracks. Cartography: Tony Burton; all rights reserved.

Chapter 23 of Geo-Mexico: the geography and dynamics of modern Mexico looks at urban issues, problems and trends. To preview more parts of the book, click here and use amazon.com’s “Look Inside” feature.

Dec 062010
 

Cancún is Mexico’s premier tourist destination, attracting more than 3 million visitors a year. A recent Associated Press report by Mark Stevenson highlights the problems faced by the resort due to the erosion of its beaches.

Cancún was developed on formerly uninhabited barrier islands on Mexico’s Caribbean coast. The islands were low-lying sand bars, held together by beach vines and the dense, interlocking roots of coastal mangroves. Hurricanes periodically swept over these small islands blowing loose sand towards the beaches on the mainland. Despite the occasional hurricane, the sandbars survived more or less unscathed until construction of Cancún, Mexico’s first purpose-built tourist resort, began in 1970.

As Cancún has grown, so the damage from hurricanes has become more serious. Category 4 Wilma in 2005 was especially destructive.

Cancún beach erosion

Cancún beach erosion. Photo: Dario Lopez-Mills/AP

Why has hurricane damage increased since 1970? Several factors are thought to play in a part in causing the increased rate of erosion of Cancún’s beaches in recent years:

  • hotels have been built too close to the shore, and too many are high-rise buildings. High-rise hotels deflect some of the wind downwards towards the ground. These wind eddies can stir up any dry surface sand in a process known as deflation.
  • hotels are too heavy. The sheer weight of high-rise hotels compacts the largely unconsolidated sediments beneath them, rendering the sediments less able to store or absorb excess water, and more liable to subsidence and structural problems. Extra weight also increases the load on slopes and leads to a higher incidence of slope failure.
  • coastal mangroves have been destroyed, removing their ability to protect the shoreline during storm events.
  • most beaches have been stripped of their original vegetation. The original beaches were protected by various adventitious vines which were quick to colonize bare sand. They would simultaneously help hold the sand in place, protecting it from wind action, and gradually add to the organic content of beaches to a point where they could support other, larger plants. Native vegetation has been mercilessly eradicated from Cancún’s beaches to create the tourism “ideal” of uninterrupted swathes of white sand.

It also appears that hurricanes and other tropical storms have become more frequent in recent decades, perhaps as a consequence of global climate change. The situation has also been exacerbated by the gradually rising sea level. Sea level on this coast is rising at about 2.2 mm/y.

Why have some of the efforts made to mitigate the beach erosion only made the situation even worse?

Following strong hurricanes (such as Wilma in 2005) Cancún has lost most of its beaches. The first attempt at beach restoration in 2006 cost 19 million dollars. In 2009, an even costlier (70 million dollar) beach restoration was carried out, using sand dredged from offshore. In one sense, the project was a resounding success. A new beach up to 60 meters wide, was created along some 10 km of coastline.

However, this new beach came at a considerable ecological cost. The pumping of sand from offshore disturbed the seafloor and damaged sealife, including populations of octupus and sea cucumbers. Fine sediments raised by the pumping traveled in suspension to nearby coral reefs, where it also had deleterious impacts.

In addition, the new beach is already being eroded away (some estimates are that up to 8% of the new sand has already been washed or blown away), so presumably if Cancún’s beaches are to be maintained in the future, beach restoration will have to become a regular event.

One hotel erected a breakwater or groyne on its beach to retain all the sand being carried along the coast by the process of longshore drift. The Associate Press article ends with a wonderful story of how the beach in front of this particular hotel was cordoned off by marines last year on the grounds that it was stolen property.

Link to 2013 news article: A fortune made of sand: How climate change is destroying Cancun

Tourism is one of Mexico’s major sources of revenue. But tourism, especially high-rise mass tourism such as that characterized by Cancún, comes with a hefty price tag. Policy-makers need to decide whether this price tag, which will only rise further in the future as we continue to damage our natural environment, is really one that is worth the cost.

Chapter 19 of Geo-Mexico: the geography and dynamics of modern Mexico looks in much more detail at Mexico’s purpose-built resorts as well as many other  aspects of tourism, resorts and hotels  in Mexico. Chapter 30 focuses on environmental issues and trends. Buy your copy today!

How good were the 2010 hurricane predictions?

 Other  Comments Off on How good were the 2010 hurricane predictions?
Dec 042010
 

In an earlier post – How many hurricanes are likely in the 2010 Atlantic hurricane season? – we reported on the predictions for this year’s Atlantic/Caribbean hurricane season

How close to reality did those predictions turn out to be?

The predictions were for 8 tropical storms, 5 moderate hurricanes (1 or 2 on the Saffir-Simpson scale), and 5 severe hurricanes (3, 4 or 5 on the Saffir-Simpson scale). At the end of the season (30 November 2010), there had been 7 tropical storms, 7 moderate hurricanes and 5 major hurricanes. In total, these storms caused 259 deaths directly, and a further 23 indirectly, with total property damage estimated at US$11.4 billion. (Note that not all of these hurricanes affected Mexico).

Atlantic Hurricane tracks, 2010

Atlantic hurricane tracks, 2010. Created by Cyclonebiskit using Wikipedia: WikiProject Tropical cyclones/Tracks. Author: Cyclonebiskit and Syntheticalconnections

So, all in all, the predictions made before the hurricane season started were pretty close to the mark, and this hurricane season was indeed one of the most active on record.

Previous hurricane-related posts include:

Hurricanes and other climatological phenomena are analyzed in chapters 4 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, so you have a handy reference guide available whenever you need it.

Hurricane Richard approaches the Yucatán Peninsula

 Mexico's geography in the Press  Comments Off on Hurricane Richard approaches the Yucatán Peninsula
Oct 242010
 

As the hurricane season draws to a close, Hurricane Richard is approaching the coasts of Belize and Mexico’s Yucatán Peninsula. For its latest position and predicted path, see Mexico’s National Meteorological Service website. [After the event, hurricane information is stored in the same site’s Historical Hurricane Archive.]

hurricane-richard-2010

Hurricane Richard is predicted to lose strength (and be downgraded to a Tropical Storm) as it crosses the Yucatán Peninsula. Even so, it will bring more heavy rains to eastern Mexico, an area still struggling to cope with the aftermath of torrential downpours earlier in the summer.

Previous hurricane-related posts:

Hurricanes and other climatological phenomena are analyzed in chapters 4 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, so you have a handy reference guide available whenever you need it.

Serious flooding in southern Mexico, August-September 2010

 Mexico's geography in the Press  Comments Off on Serious flooding in southern Mexico, August-September 2010
Sep 082010
 

International media have been focusing attention in recent weeks on massive floods in Pakistan and China. While not on the same scale as the tragedy unfolding in Pakistan, Mexico is dealing with the aftermath of its own very serious flooding in the southern part of the country. Weeks of torrential downpours, with rainfall in many areas reaching more than double the yearly average, have led to widespread inundations.

Floods in Tabasco

The worst flooding has been in the lowland Gulf Coast states of Veracruz and Tabasco, where the channels of major rivers have been unable to cope with the volumes of water fed into them by their network of tributaries. These tributaries begin in the mountainous areas upstream, which received the heaviest rainfalls, in the states of Chiapas and Oaxaca,  which are also experiencing serious flooding. According to the Associated Press and Mexico City daily Milenio, over 300,000 people are directly affected, and tens of thousands have been forced from their homes.

The Papaloapan River has burst its banks and caused record flooding in parts of Oaxaca and Veracruz.  Some of the worst flooding has been in Tlacotalpan, a UNESCO World Heritage Site in a low marshy area about ten kilometers from the Gulf of Mexico, between Veracruz City and Coatzacoalcos.  President Felipe Calderon personally assessed the damage and expressed solidarity with the flood victims by wading a kilometer through the flooded streets of Tlacotalpan.  He ordered six hundred Mexican sailors into the flooded areas to help local residents.

The low-lying state of Tabasco has been hit the hardest.  The homes of over 120,000 people are flooded and over 180,000 hectares belonging to 20,000 people have been lost. This region has repeatedly suffered serious flooding in recent years; a controversial plan for flood protection in this area has never been completed.

Villahermosa, the capital of Tabasco, has been flooded once again. It suffered catastrophic floods in November 2007 and November 2009.  The recent Villahermosa flooding is exacerbated by the controlled releases of water from the massive Malpaso and La Angostura dams in the upper reaches of the Rio Grijalva basin. The dams are essentially filled to capacity; with more rains expected in the next two months, water must be released to provide spare capacity to avoid even greater flooding in the wettest fall months.  The same situation is occurring with the dams in the Papaloapan basin.

Useful ink:

  • Photo gallery of flooding in Tlacotalpan, Veracruz

Rivers, floods and water-related issues are discussed in chapters 6 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy.

An update on flood protection in the state of Tabasco, Mexico

 Excerpts from Geo-Mexico, Updates to Geo-Mexico  Comments Off on An update on flood protection in the state of Tabasco, Mexico
Aug 032010
 

The small, oil-rich state of Tabasco, one of Mexico’s wettest states, is regularly subjected to serious flooding. Much of the state is a wide coastal plain of sediments brought by rivers from the mountains of Chiapas and Guatemala. Two major rivers—the Grijalva and the Usumacinta—converge in the Pantanos de Centla wetlands. These rivers have meandering, braided channels and highly variable flows, partly because of hydropower dams far upstream.

The state’s high incidence of floods has been exacerbated by subsidence and deforestation due to oil and gas extraction which has led to excessive silting of river channels. Looking to the future, rising sea levels will only increase this area’s vulnerability to flooding.

The flood of 2007

Several days of heavy rainfall due to a low pressure system led in late October and early November 2007 to massive floods,  called at the time by President Felipe Calderón “one of the worst natural disasters in the history of the country.” About 80% of Tabasco was under water at one point.

Tabasco produces 80% of Mexico’s total cacao and 40% of its bananas; the losses of farm harvests alone were estimated at $480 million. The floods disrupted the lives of more than a million residents, and 20,000 people were forced to seek emergency shelter. The state capital Villahermosa, located near the junction of three branches of the Grijalva River, was particularly badly hit.

It has been claimed that the 2007 floods would have been much less serious if funds allocated for hydrologic infrastructure improvements had not been misappropriated.

2008 Hydrological Plan

A new Tabasco Hydrological Plan was announced in 2008. The $850 million plan should ensure the integrated management of six river basins and major improvements to the systems for storm tracking, weather forecasting and disaster prediction. Several rivers will be dredged and the coast will be reinforced with breakwaters and sea walls.

2009 Flood

Unfortunately, the plan could not be implemented in time to prevent serious damages from the next big Tabasco flood in early November 2009 which inundated the homes of more than 200,000 people.

2010 update on Hydrological Plan

Now, we learn from The OOSKA News Weekly Water Report for Latin America and the Caribbean (28 July 2010)  that state politicians are considering a lawsuit against the National Water Authority for failure to competently oversee all the various contracts involved in the 2008 Hydrological Plan. A local newspaper in Tabasco state reports that 10 companies failed to deliver the dredging and flood protection works they had been contracted to do, and so far, the National Water Commission has failed to collect fines of about 770,000 dollars for non-compliance, as stipulated in their contracts. The original contracts were valued at 6.7 million dollars, and were apparently paid in advance. All work was scheduled to have been completed by March of 2009.

Federal politicians are now claiming that the National Water Authority’s failures led directly to further serious flood damage in late 2009, which would have been avoided if the work had been completed on time.

According to a Mexico City daily, Tabasco’s 2008 Hydrological Plan is still only approximately 50% complete, as of July 2010.

Rivers, floods and water-related issues are discussed in chapters 6 and 7 of Geo-Mexico: the geography and dynamics of modern Mexico. Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy…

Jul 102010
 

NEW (Sunday 11 July): At present the discharge of the Río Bravo/Grande is decreasing, but a secondary peak discharge is expected to sweep downstream from late Monday through Tuesday, depending on the precise location.

The following summary of recent developments related to Hurricane Alex has been compiled from a variety of news reports.

Loss of life
In Coahuila, memorial services have been held for Horacio del Bosque Dávila, the state’s Director of Public Works, who died alongside seven colleagues while assessing the flood damage from the air, when their light plane crashed.

Four more deaths from drowning have been reported, with the discovery of four bodies on the bank of the Río Bravo near Ciudad Acuña.

State of emergency
A state of emergency has been declared in many more municipalities, bringing the total number of affected municipalities to 43 in the state of Nuevo León and 25 in Coahuila.

The municipalities recently added to the list are:

  • Nuevo León: Agualeguas, Galeana, Doctor González, García, Marín, General Zuazua, Mina, Hidalgo, Iturbide, Los Herreras, Parás and Pesquería.
  • Coahuila: Los Acuña, Allende, Cuatrociénegas, Guerrero, Hidalgo, Jiménez, Juárez, Morelos, Múzquiz, Nava, Piedras Negras, Progreso, Sabinas, San Juan de Sabinas, Villa Unión and Zaragoza.

Highways and transport
Both main highways between Monterrey and Nuevo Laredo are currently closed, and expected to remain so for another 3-4 days.

  • Federal highway 85D is flooded between km 143 and 146, near Sabinas Hidalgo, due to the Río Salado overflowing its banks.
  • Highway 85 (the non-toll highway) is closed at km 155, near Ciénega de Flores, because of a badly damaged bridge.

Cross border rail services were also suspended for a time.

International Bridge #1 was closed for more than 24 hours as the Río Bravo peaked, but has now reopened. Not surprisingly, truck traffic across the international bridges into Nuevo Laredo has been severely affected, especially since they currently have no way to proceed further south.

The vehicle inspection offices on the Mexican side of the bridge were flooded.

Several roads in and around the city of Monterrey have been closed due to flooding and resulting landslides.

In Tamaulipas, 41,700 people have been forced out of their homes, in 19 municipalities. In Hidalgo municipality, work has begun on erecting an emergency bridge to reconnect 14 small settlements to the rest of the state following the destruction of the old bridge. The settlements include El Chorito, one of the most revered pilgrimage centers in north-eastern Mexico.

Flow levels on the Río Bravo/Grande
The flow levels on the Río Bravo/Grande are unprecedented in recent times. All floodgates at the Venustiano Carranza dam have had to be opened, and are expected to remain so for 4 or 5 more days.

The Río Bravo has not experienced flows like this since the construction in 1968 of Presa La Amistad. The river peaked at a height of 13 meters, more than 12 meters above its normal level for this time of year. Its peak discharge was 7,500 cubic meters per second, also a post-dam record.

Agriculture
A total of up to 300,000 hectares of agricultural land have been affected by flooding. Tamaulipas has applied for emergency farming aid for an area of 153,500 hectares in 32 municipalities.

The most valuable crops to be affected are sorghum, corn, cotton, chile, tomato, alfalfa and canteloupe. Sorghum production alone is likely to fall by one million tons.

Property damages
The cost of the repairs needed for the badly damaged potable water network in the city of Monterrey (Nuevo León) is estimated at 260 million dollars.

The hurricane has damaged more than 1,000 schools in Nuevo León, out of a total of 3,535. At least 60 schools suffered severe structural damage. The estimated repair costs are about 30 million dollars.

This YouTube video is a collection of photos showing the extraordinary amount of damage done in the city of Monterrey.

Aid
The loss of life and property damages might have been much greater had it not been for efficient emergency services and disaster response. Aid is reaching almost all the victims of the floods, either via the Red Cross or via Mexico’s Armed Services (Army and Navy).

Hundreds of additional firemen, rescue crews and police have been drafted in to help.

A shelter for more than 800 people is operational in the city of Matamoros.

A vaccination campaign is already underway, with measures being taken to prevent an outbreak of dengue fever.

Telmex (Teléfonos de México) and other phone companies are giving residents in areas affected by flooding up to a week of free local and national long distance calls.

Miscellaneous
Two undocumented Central American migrants were rescued from the river after having been swept more than 5 kilometers downstream. They had tried to cross the river using an inner tube. It had taken one of them two months to reach this border crossing from his home in Honduras.

A rescue helicopter plucked 8 people to safety from the steel tower supporting the community water tank in El Camarón, located between Nuevo Laredo and Cd. Anahuac. They had been marooned when the River Salado overflowed. Local officials believe another five people may also have been trapped, but have so far failed to locate them.

Previous posts related to Hurricane Alex:

Mexico’s climatic hazards, including hurricanes, are analyzed in chapter 4 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, so you have a handy guide to the “back story” behind Mexico’s current affairs.

More reports of damage from Hurricane Alex, and another storm on the way

 Mexico's geography in the Press, Updates to Geo-Mexico  Comments Off on More reports of damage from Hurricane Alex, and another storm on the way
Jul 082010
 

Update on the aftermath of Hurricane Alex, Thursday 8 July, 2010

The Mexico-USA border area may be in for a very wet week, since Tropical Depression 2 (which would become Hurricane Bonnie if its wind speeds increase) is now approaching the area from the Gulf of Mexico. Weather Underground has more details and maps showing the possible storm paths.

The Río Bravo (Grande) is expected to peak in Laredo at 13 meters (42 feet) at Bridge 1, and possibly even higher at the Columbia bridge. Cross-border travelers in that area are best advised to delay their travel until the river level is well on its way down. Otherwise, anticipate long delays and time-consuming diversions.

State officials in Coahuila now say that at least 80,000  people in that state are homeless, 20,000 homes are uninhabitable, and 40,000 homes are still without drinking water.

The Nuevo León state chapter of the National Chamber of Housing Developers claims that at least 7,000 homes in Nuevo León need major repairs or rebuilding as a result of Hurricane Alex.

This YouTube video of the flood gives a good idea of the power of the water flow in the city of Monterrey (Nuevo León).

Previous posts related to Hurricane Alex:

Mexico’s climatic hazards, including hurricanes, are analyzed in chapter 4 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, so you have a handy guide to the “back story” behind Mexico’s current affairs.

Mass evacuations and flood alerts follow Hurricane Alex

 Mexico's geography in the Press, Updates to Geo-Mexico  Comments Off on Mass evacuations and flood alerts follow Hurricane Alex
Jul 072010
 

The final death toll from Hurricane Alex last week stands at 12. It is a tribute to the effective preparations made by residents and authorities in advance of the storm, and to relief efforts, that more people did not lose their lives.

The center of Monterrey, an industrial center which is Mexico’s third largest city, was briefly turned into a raging torrent, with widespread damage to roads and infrastructure. Click here for a photo gallery showing some of the extensive damage caused by Huricane Alex.

Hurricane Alex

Hurricane Alex. Photo: NOAA. Click to enlarge.

In addition to those made homeless as a direct result of the storm, a further 18,000 people have been evacuated from their homes because they are downstream of the Venustiano Carranza dam, located about 70 km (43 miles) away, which is now at bursting point.

The authorities in Ciudad Anahuac (a short distance south-west of Nuevo Laredo) have opened some of the dam’s floodgates to ease the water pressure but the situation is still reported to be critical. The opening of the floodgates released 600 cubic meters of water a second into the Río Salado, a tributary of the Río Bravo/Grande. Meanwhile, residents have been moved to shelters in nearby towns.

Santos Garza Garcia, the town’s mayor, told reporters that “It was preferable to have controlled flooding than having the whole town disappear.”

In a related development, the bi-national International Boundary and Water Commission, which adjudicates Mexico-USA border issues, ordered the release of 1,000 cubic meters a second (35,000 cubic feet per second) of floodwater from the Amistad reservoir into the Río Grande. The Amistad reservoir straddles the border upstream of the cities of Del Río (Texas) and Ciudad Acuña (Coahuila).

The heavy rains had already swollen the Río Bravo/Río Grande (which forms along the Mexico-USA border) to dangerous levels. The level of the river is being continuously monitored. Its level has risen by as much as 6 meters (20 feet) above normal. As a precaution, several border crossings, including the international bridge between Laredo (Texas) and Nuevo Laredo (Tamaulipas) have been closed.

It is the first time since 1995, that an Atlantic hurricane has struck Mexico’s Gulf coast as early as June. Everyone hopes that the main hurricane season, in July-August-September, does not bring further loss of life and property damage.

Additional note added Thursday July 8: The Mexico-USA border area may be in for a very wet week, since Tropical Storm 2 (which would become Hurricane Betty if wind speeds increase) is now approaching. Weather Underground has more details and maps showing the possible storm paths.

Earlier posts:

Mexico’s climatic hazards, including hurricanes, are analyzed in chapter 4 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, so you have a handy guide to the “back story” behind Mexico’s current affairs.