Jul 062013
 

Popocatepetl Volcano (“Don Goyo” to the people living in its shadow) continues to erupt. On 4 July, several airlines, including American Airlines, US Airways, Delta Airlines and Alaska Airlines suspended operations to and from Mexico City for several hours, resulting in numerous cancelled flights.

Mexico’s National Disaster Center (Cenapred) provides daily updates (in both English and Spanish) on the volcano’s activity. The Volcanic Alert Level was raised today (6 July) to Yellow Phase 3. This includes:

  1. Access is restricted within a radius of 12 km from the volcano’s crater. Permanence in this area is not allowed.
  2. The road between Santiago Xalitzintla (Puebla) and San Pedro Nexapa (Mexico State), including Paso de Cortes, is open only to authorized traffic.
  3. Civil Protection authorities maintain preventive procedures, according to operative plans.
  4. People are advised to follow guidelines provided by official information bulletins.

There are only two higher levels (both described as “Alarm” rather than “Alert”): Red Phase 1 and Red Phase 2.

Since our last update in March, several spectacular images of the volcano have been released.  Activity increases every two or three weeks, as the following brief reports, based on the Cenapred daily updates, reveal:

8 May – Ash rose 3000 m above the volcano before falling on several municipalities in the states of Puebla and Tlaxcala. Residents were advised to sweep it up without using any water to prevent the ash from sticking together and blocking drains. Mexico City’s international airport was closed to flights for a short time.

14 May – Eruptions continued, accompanied by an increase in seismic activity. The Alert Level was raised to Yellow Phase 3 for several days, with evacuation plans about to be implemented. A dome of lava, about 350 m across and 50 m thick, had formed in the crater, prior to being destroyed in an eruption which formed a 3000 m high ash cloud and sent incandescent fragments (“volcanic bombs”) up to 1000 m from the crater. The volcano’s activity subsided within days and the alert level was reduced to Yellow Phase 2.

17 June – A month later, another explosion (see photos) sent ash more than 4000 m into the air, and threw volcanic bombs up to 2000 m from the crater, starting a series of minor wild fires. Winds blowing towards the northwest carried ash towards the south-eastern section of Mexico City. A week later (24 June), minor amounts of ash fell in eight municipalities in the state of Mexico: Amecameca, Tlalmanalco, Temamatla, Cocotitlán, Ozumba, Atlautla, Ecatzingo and Chalco. The local authorities reported no damage, but reminded residents, among other things, to avoid wearing contact lenses if at all possible. The next day (25 June), ash fell on some southern and eastern parts of Mexico City. Three international flights scheduled to land in Mexico City airport were diverted to Querétaro airport.

The typical sequence of activity is shown in the photos. First, pressure from molten rock underground (magma) leads to the formation of a dome of lava in the summit crater (photo below).

Lava dome building in crater of Popocatapetl Volcano

Lava dome building in crater of Popocatapetl Volcano

These domes eventually either collapse or are destroyed by explosions (photos below) that lessen the pressure beneath the surface.

NasaPopocatapetl Volcano erupts, 17 June 2013

Popocatapetl Volcano erupts, 17 June 2013

Following the explosion (shown by the satellite image below), a new dome begins to form, and the cycle of eruptive activity continues.

Geophysicists from the National University (UNAM) who monitor the volcano and analyze its gaseous emissions say that between 1994 and 2008 the volcano emitted 30 megatons (30 million tons) of gases and that it looks set to continue erupting for several years. Popocatepetl is one of the top five volcanoes in the world for emissions of sulfur dioxide. The volcano has added between 6000 and 8000 tons/day to the atmosphere in recent months. Lead researcher Hugo Delgado Granados has been quoted in press reports as saying that the continued gaseous emissions are good news, since the constant releases of pressure should preclude a more explosive eruption.

This YouTube compilation of webcam videos of the volcano provides a time-condensed view of the eruption of 17 June 2013. The 30-second video represents a period of 20-30 minutes, during which the volcano exploded into action, sending a cloud of gases, ash and volcanic fragments high into the air.

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Progress made in Tabasco’s flood control plan

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Jul 012013
 

The El Macayo dam on the border of Tabasco and Chiapas states in southern Mexico was officially inaugurated last month. The 90-million-dollar dam, which has been under construction for a decade, is designed to regulate flow along the River Grijalva (aka Mexcalapa and Carrizal) that flows through the city of Villahermosa in Tabasco.

Presa El Macayo (Chiapas/Tabasco)

Presa El Macayo (Chiapas/Tabasco)

The city and surrounding settlements have suffered severe flooding many times in recent years, and the El Macayo dam should bring some much-needed relief to around 700,000 people who live in the areas of greatest risk..

Villahermosa floods 2007

A flooded district of Villahermosa, the capital of Tabasco state in 2007. Photo: AFP

Why does the state of Tabasco have a high risk of floods?

The Grijalva–Usumacinta river system is one of the world’s largest in terms of volume. It is easily the river system with the greatest flow in Mexico. It is essentially a double river, with two branches of similar length which both start in Guatemala. Each branch flows about 750 km (465 mi) through Chiapas before they unite in Tabasco about 25 km from the Gulf of Mexico. Each of the two branches has a flow of about 14% of Mexico’s total. The flow of the combined Grijalva–Usumacinta River is about twice that of the Missouri River in the USA.

The state of Tabasco itself receives an average rainfall three times higher than Mexico’s national average rainfall, and accounts for 38% of the country’s freshwater.

Given these conditions, it is not surprising that the state of Tabasco is one of the most vulnerable states for flooding in Mexico. The UN’s Economic Commission for Latin America and the Caribbean has estimated that the state suffered around $4.5 billion in losses from flooding between 2007 and 2011.

Integrated Hydrology Plan

The dam is only one small component in an Integrated Hydrology Plan that is has been designed by the National Water Commission, Conagua. The agency has been assigned more than $110 million this year to complete existing hydrology-related infrastructure projects and update flood protection plans. The previous government spent $640 million to begin a flood management program for the state; this included building flood prevention infrastructure, dredging the major rivers and constructing flood-alleviation channels.

Arturo Núñez, governor of Tabasco state, says that the state’s flood management program should include the relocation of residents currently living in the most vulnerable areas, as well as reforestation of the drainage basins, continued regular dredging of the main rivers, and a reorganization of irrigation systems.

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Jun 172013
 

Today (June 17) is the UN’s “World Day to Combat Desertification and Drought.”

How does Mexico stand right now in relation to drought? Drought currently affects about 40% of the country (see map). Some parts of northern Mexico have been experiencing a severe drought for almost three years. The worst affected states are Chihuahua, Nuevo León, Coahuila, Durango, Zacatecas, Tamaulipas, San Luis Potosí, together with parts of Querétaro, Aguascalientes, Sinaloa and Sonora.

Areas suffering from short-term and long-term drought, April 2013. Click map to enlarge.

Areas suffering from short-term and long-term drought, April 2013. Click map to enlarge.

Last year’s rains did reduce the area suffering from drought from 55.9% of Mexico to 38.6%, but that figure has risen to well over 40% this year.

In 2012, and earlier this year, many major cities, including Mexico City and Guadalajara, had to enforce water rationing for several months, supplying water to individual households only on certain days each week.

As this year’s rainy season begins in central Mexico, dozens of reservoirs are at critically low levels. Reservoirs in Coahuila average only 10% of their capacity, only slightly better than those in San Luis Potosí (12%). Even the populous state of Jalisco faces problems; its reservoirs are at 27% of capacity.

Things are unlikely to improve any time soon since the current long range forecast for this rainy season is for 30% less precipitation than the long term average.

The drought has already caused significant losses to farmers. Livestock owners in northern Mexico have culled herds and are having to buy in supplies of water to top up their private wells. Rainfall so far in 2013 has been well below long-term averages in central and northern Mexico, which may limit the region’s productivity of rain-fed agriculture (mostly wheat, corn, sorghum and other fodder crops).

Authorities at the three levels of government (federal, state and municipal) in many regions are calling for urgent concerted action to help farmers as well as to ensure supplies of drinking water to towns, cities and rural communities.

In Tamaulipas, at least 60 rural communities are confronting a critical water shortage. Farming representatives argue that while the National Water Commission (Conagua) has guaranteed water supply for urban areas, many rural areas remain vulnerable, and lack both potable water and food support on account of harvest failures due to lack of rain. In Tamaulipas alone, drought has affected 22,000 hectares and killed 800 head of livestock in the past year.

In Nuevo León, citrus farmers fear that their harvest, which begins in October will be 40-50% lower than usual. The state government is supporting a 35-million-dollar support program for farmers which includes supplying water by truck, rehabilitating deep wells and offering subsidies for water that farmers buy direct from private suppliers. The spring harvest in Nuevo León was lost completely, and a “severe drought emergency” has been declared in at least 14 municiapliites (Allende, Cadereyta, Dr. Arroyo, General Terán, Higueras, Juárez, Lampazos, Rayones, Sabinas Hidalgo, Santa Catarina, Villaldama, Hidalgo, García and Mina) allowing them access to federal aid.

Besides loss of livestock and crops, the prolonged drought in Mexico is having many other effects, which include:

Migration – In Durango state, more than 1500 Mennonites have left their homes due to the drought, according to Mennonite leader Enrique Peter Klassen, with some of the migrants headed for neighboring state of Chihuahua and others emigrating to Canada.

Wildfires – The first four months of 2013 was the third worst season for forest fires (more than 7000 were reported) in recent history, after 1996 and 2011. According to the National Forestry Commission (Conafor), wildfires ravaged 170,000 hectares, mostly grassland and wooded pastureland, in the first four months of this year. The states which suffered most were Oaxaca (21,000 ha), Baja California Sur (16,000), Guerrero (13,857) and Jalisco (13,697).

Lake Chapala – In the past two years, the level of Mexico’s largest natural lake, Lake Chapala, has once again fallen to crisis levels. (The lake has a long history of fluctuations in level, discussed in detail in our Geo-Mexico, the geography and dynamics of modern Mexico). The lake currently holds 2.84 million cubic meters of water, about 36% of its capacity. Its level has fallen 1.43 meters since last year’s rainy season, the lake’s most dramatic decline for 20 years. The rainy seasons in 2011 and 2012 raised the lake level by only 24 cm and 50 cm respectively, so unless this year’s rains are exceptionally heavy, the lake will continue to drop.

Previous posts related to drought:

Hurricane names and forecast for 2013

 Mexico's geography in the Press  Comments Off on Hurricane names and forecast for 2013
May 112013
 

The 2013 hurricane season in Mexico is underway. The “official” hurricane season is from 15 May to 30 November each year for Pacific coast storms, and from 1 June to 30 November for Atlantic storms, though most hurricane activity is concentrated in the months from July to September. Hurricanes are also known as typhoons or tropical cyclones.

The table shows the World Meteorological Organization’s official list of 2012 hurricane names. Note that male and female names alternate. Names are often reused in future years, with the exception of the names of any particularly violent storms, which are officially “retired” from the list for a long time.

2013 Hurricane Names for the Atlantic, Gulf of Mexico and Caribbean
AndreaGabrielleLorenzoRebekah
BarryHumbertoMelissaSebastien
ChantalIngridNestorTanya
DorianJerryOlgaVan
ErinKarenPabloWendy
Ferdinand

2013 Hurricane Names for the Eastern Pacific
AlvinGilManuelTico
BarbaraHenrietteNardaVelma
CosmeIvoOctaveWallis
DalilaJuliettePriscillaXina
ErickKikoRaymondYork
FlossieLorenaSoniaZelda

In their early season forecast for this year, Philip Klotzbach and William Gray, researchers at Colorado State University,  expect hurricane activity in the Atlantic to be significantly higher than the 1981-2010 average. They write that, “The tropical Atlantic has anomalously warmed over the past several months, and it appears that the chances of an El Niño event this summer and fall are unlikely”. (A strong el Niño is likely to minimize Atlantic hurricane activity). They predict that in the 2013 season 18 named storms will form in the Atlantic: 9 tropical storms, 5 moderate hurricanes (1 or 2 on the Saffir-Simpson scale), and 4 severe hurricanes (3, 4 or 5 on the Saffir-Simpson scale). These forecasts will be updated on 3 June and 2 August.

saffir-simpson-scale

For the Pacific coast, Mexico’s National Meteorological Service (Servicio Metrológico Nacional, SMN) is expecting 14 named storms: 6 tropical storms, 4 moderate hurricanes (1 or 2 on the Saffir-Simpson scale), and 4 severe hurricanes (3, 4 or 5 on the Saffir-Simpson scale). The SNM publishes regular updates on hurricane activity (in Spanish) on its webpage and via its Twitter account: @huracanconagua.

How accurate was the forecast in 2012?

The late season (3 August) prediction for 2012 (last year) was for 14 named storms in the Atlantic: 8 tropical storms, 4 moderate hurricanes and 2 severe hurricanes. In reality, the 2012 Atlantic season had 19 named storms: 9 tropical storms, 8 moderate hurricanes and 2 severe hurricanes.

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Popocatapetl Volcano and Colima Volcano continue to erupt

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Mar 302013
 

In our series of brief updates on topics featured in previous Geo-Mexico posts, we look this week at the continuing eruption of two major volcanoes: Popocatapetl Volcano (between Mexico City and Puebla) and Colima Volcano (on the Jalisco-Colima state border in western Mexico).

Popocatepetl, 30 July 2012

Popocatepetl, 30 July 2012

Since our previous post, about a year ago, entitled Alert level rises as Popocatepetl volcano starts to erupt, Popocatapetl Volcano (photo) has continued to be active, with up to 250 activity events a day. The alert level has been reduced slightly to Yellow Phase 2, the fourth highest level. This level indicates intermediate scale explosive activity and possible expulsion of lava, explosions of increasing intensity and wind-blown ash falling on nearby villages. The volcano is monitored daily, and updates from CENAPRED  (in Spanish and English) are issued every 24 hours.

The report issued on 27 March is typical of recent months. In the previous 24 hours, there were 83 low intensity events with emissions of gas, water vapor and ash. The two largest events sent material rising 1000 meters and 600 meters into the atmosphere respectively, before the wind blew the material north eastwards (away from Mexico City).

Colima Volcano

In January 2013, we reported how Colima Volcano erupts, destroying lava dome first created in 2007. The volcano has continued to erupt in the ten weeks since then. The experts monitoring the volcano have reported up to 200 eruptive events a day, with numerous minor emissions of lava. Local villagers have been asked to remain on alert, though the experts are not yet calling for any villages to be evacuated.

The image below (source: Nasa Earth Observatory) shows Colima Volcano in 2010, part way into its current eruptive phase which is expected to last several years. The image shows the evidence at that time of four different types of volcanic activity:

  • lava dome growth
  • explosive eruptions
  • flank collapse
  • lava flows.

(Note that the 2013 eruptions have significantly altered the top of the volcano since this image was taken).

Nasa Earth Observatory)

Colima Volcano in 2010 (Nasa Earth Observatory)

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Paricutin Volcano in Mexico celebrates its 70th birthday

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Feb 202013
 

Today (20 February 2013) marks the 70th anniversary of the first eruption of Paricutín Volcano in the state of Michoacán in western Mexico.

The landscape around the volcano, which suddenly started erupting in the middle of a farmer’s field in 1943 and which stopped equally abruptly in 1952, is some of the finest, most easily accessible volcanic scenery in the world. A short distance northwest of Uruapan, this is a geographic “must see”, even if you can only spare a few hours.

Paricutín Volcano, 16 July 1943

Paricutín Volcano, 16 July 1943

What makes Paricutín so special is that in all of recorded history, scientists have had the opportunity to study very few completely new volcanoes in continental areas (whereas new oceanic island volcanoes are comparatively common). The first two new volcanoes formed in the Americas in historic times are just one hundred kilometers apart. The first was Jorullo, which erupted in 1759, and the second is Paricutín.

Dominating the valley where Paricutín now exists is the peak of Tancítaro, the highest point in the state of Michoacán at 3845 meters (12,615 feet), and sometimes snow-capped in winter. In 1943, the local Purépechan Indians inhabited a series of small villages and towns spread across the valley floor. The villages included Angahuan, which still exists today, Paricutín, where all 500 people lost their homes, and San Juan Parangaricutiro. The latter was once famous for hand-woven bedspreads and quilts and consequently known as San Juan de las Colchas (bedspreads). Its church, begun in 1555, had never been finished and only ever had a single tower.

On 20 February 1943, a local campesino named Dionisio Pulido was tending his crops with his wife Paula, their son and a friend. At about 4:00pm, they noticed a small crack and felt the ground shaking under their feet. While they watched, the ground rose more than 2 meters and smoke rose into the air, accompanied by whistling noises and the smell of sulfur. Sparks set fire to a nearby pine tree. Not surprisingly, they fled!

Legend has it that Dionisio first tried to smother the emerging volcano with loose rocks and afterwards was of the opinion that the volcano would never have erupted if he hadn’t plowed his field, but such reports are almost certainly pure fiction.

The volcano grew rapidly, providing onlookers, visiting vulcanologists and residents alike, with spectacular fireworks displays. The month of March was a particularly noisy time in Paricutín’s history—explosions were heard as far away as Guanajuato and ash and sand were blown as far as Mexico City and Guadalajara.

After one week, the volcano was 140 meters high, and after six weeks 165 meters.

In April 1943 there were major lava flows, originating from about 10 kilometers underground. These lavas were basaltic; their chemistry suggested temperatures inside the volcano of between 960o and 1020oC. More than 30 million metric tons of lava flowed from the volcano between April and June 1943, raising the volcano’s height to more than 400 meters before its first birthday.

In early 1944, another lava flow streamed in a gigantic arc reaching the outskirts of the town of San Juan Parangaricutiro. Fortunately, the town had already been abandoned following many earthquakes, some of which rang church bells as far away as Morelia! The lava flowed about 30 meters a day and went right through the church but, miraculously, left the main altar standing. The parts of the church which survived in “old” San Juan, including its altar, can still be visited today, though reaching them involves clambering over jagged blocks of lava.

The villagers who had abandoned the town were escorted to Uruapan for safety. Some of them later founded a new town called San Juan Nuevo. Other villagers moved away to live in Los Reyes, Uruapan, Angahuan, Morelia and Guadalajara.

Yet another lava flow buried the village of Paricutin which fortunately had also been evacuated in time. Nothing remains of this village, covered by lava which is more than 200 meters thick in places! A small cross atop the lava marks its approximate position. Besides lava, ashes and dust were also thrown out by the volcano. The ash was 1 millimeter thick in Guadalajara, 25 centimeters thick in Angahuan, and 12 meters thick near the cone. The volcano rose 410 meters above the original ground surface.

Suddenly, in February 1952, nine years after the volcano first erupted, the lava stopped flowing. In many places, plumes of hot steam still rise as fumaroles from the ground, ground that is still most distinctly warm to the touch.

Enjoying a full day at Paricutín has been made much easier since the construction of rustic tourist cabins on the edge of Angahuan village. The restaurant, which serves tasty local specialties, gives clients a panoramic view encompassing the lava and the half-buried church. A small permanent exhibition of maps, charts and photographs in one of the cabins, describing the volcano’s history and the surrounding area, was inaugurated in February 1993 to commemorate the 50th anniversary of the volcano.

Horses can be hired for a trip to the church or to the more distant cone of the volcano. The latter requires an early start since the last part involves clambering up the loose ashes and cinders which comprise the cone and scrambling onto the narrow rim of the truly magnificent crater. A marvelous view can be enjoyed from atop the crater rim and only then can the full extent of the area devastated by the volcano be fully appreciated. Nothing can quite have prepared you for this startling lunar-like landscape.

Note:

This post is a lightly edited extract from my “Western Mexico: A Traveler’s Treasury” (Sombrero Books, 2013). Chapter 35 describes Paricutín Volcano and its surrounding area, including the fascinating indigenous village of Angahuan, in much more detail. “Western Mexico: A Traveler’s Treasury” is also available as either a Kindle edition or Kobo ebook.

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The crater lake of Santa María del Oro yields evidence for climate change

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Feb 142013
 

A magnificent crater lake nestles in a centuries-old volcanic crater a short distance east of the town of Santa María del Oro in Nayarit.

The connecting road from Highway 15 first passes through the former mining town of Santa María del Oro and then rises slightly to offer a splendid view of the beautiful slate-blue lake (known locally as “La Laguna”), set in a ring of verdant hills. In recent years, the lake, a good example of a geomorphosite, has become important for tourism with accommodations ranging from RV spaces to a boutique hotel. It takes about an hour and a half to stroll round the track that encircles the crater lake. Other attractions include visiting an abandoned gold mine (which offers a glimpse into the area’s past), birding, mountain biking, swimming or hiring a rowboat or kayak to venture out onto the lake.

Crater Lake, Santa María del Oro. Credit: Tony Burton

Crater Lake, Santa María del Oro. Credit: Tony Burton

This usually quiet lake has proved to be a valuable source of information for geologists and climatologists investigating the history of climate change in this region of Mexico.

The researchers who published their findings in 2010 in the Bulletin of the Mexican Geological Society extracted a sediment core from the deepest part of the lake. The relatively small area of the drainage basin surrounding the lake and the relatively steep slopes of surrounding hills mean that the sediments entering the lake are rarely disturbed after they are deposited. Wind and wave action are limited. The depth of the lake (maximum 65.5 meters) also helps to ensure that sediments remain undisturbed for centuries. This gives perfect conditions for a reliable sediment core.

Santa María del Oro. Credit: Google Earth

Santa María del Oro. Credit: Google Earth

The team analyzed the titanium, calcium and magnetism levels of successive thin slices of the core. By comparing the core with historic records and previous tree ring analyses from the same general area, they were able to accurately date each slice. The titanium levels in each slice allowed the researchers to quantify how much runoff occurred in that year, a proxy indicator of precipitation.

The team identified 21 significant drought events over a period of 700 years. The six most marked droughts occurred in 1365–1384, 1526, 1655-1670, 1818, 1900 and 1930-2000. They found periodicities of 25, 39, 50, 70 and 117 years for drought events, meaning that droughts occurred at fairly regular intervals of about 20-25 years.

The researchers then looked at the possible correlation between periods of drought and two distinct climatological factors: a shift to the south in the position of the Inter Tropical Convergence Zone (ITCZ) in summer and the occurrence of El Niño Southern Oscillation (ENSO) events. When the ITCZ does not extend as far north as usual during Mexico’s summer rainy season, states such as Nayarit and Jalisco receive less than their normal amount of rainfall. During ENSO events, rainfall is also diminished in central and western Mexico.

Of the 21 droughts identified and studied, 7 proved to be statistically linked to ENSO events, 10 to ITCZ movements, and the remaining 4 events were closely linked to a combination of both.

As the study concludes, titanium analysis of sediments may allow for a more refined record of climate change in the period prior to reliable historic or instrumental records which might improve the understanding of how and why climate change occurred in past

Santa María del Oro is also worth visiting because it is only a short distance away from the edge of the canyon of the River Santiago and the El Cajón hydro-electric power project, one of three major HEP projects located along that river.

Source article:

Susana Sosa-Nájera, Socorro Lozano-Garcí, Priyadarsi D. Roy and Margarita Caballero. Registro de sequías históricas en el occidente de México con base en el análisis elemntal de sedimentos lacustres: El caso del lago de Santa María del Oro. Boletín de la Sociedad Geológica Mexicana, Vol 62, #3, 2010, p 437-451.

Santa María del Oro and surrounding areas are described in chapter 24 of the recently published 4th (Kindle/Kobo) edition of my Western Mexico: A Traveler’s Treasury (Sombrero Books, 2013).

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Colima Volcano erupts, destroying lava dome first created in 2007

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Jan 142013
 

Colima Volcano (aka the Volcán de Fuego) is one of the westernmost volcanoes in Mexico’s Volcanic Axis, which straddles the country from west to east. The Volcano’s summit is only 8 km (5 miles) from the inactive Nevado of Colima volcano, Mexico’s sixth-highest peak, which rises 4260 m (13,976 ft) above sea level. (Curiously, despite their names, the summits of both volcanoes are actually located in the state of Jalisco and not the state of Colima.)

The elevation of Colima Volcano is officially given as 3820 m (12,533 ft) above sea level. In the past 400 years, it has been the most active volcano in Mexico, having erupted at least 30 times since 1576.

It is also considered to be one of the country’s most dangerous volcanoes. Numerous villages in its shadow keep a wary eye on its level of activity, and emergency evacuations have become a regular event in the past fifty years.

Colima Volcano, 11 Jan 2013. Photo: Protección Civil.

Colima Volcano forms new crater, 11 Jan 2013. Photo: Edo de Jalisco Protección Civil.

On a geological time-scale, the volcano first erupted about five million years ago in the Pliocene period, long after activity ceased at the nearby, and higher, Nevado de Colima. It quickly developed into a large volcano which partially blew apart or collapsed during Pleistocene times to form a caldera, five kilometers across. A new cone developed inside the caldera. This is the Volcán de Fuego we see today.

The cone is built mainly of pyroclastic materials (ashes and volcanic bombs) of andesitic composition together with some basaltic lava, making it a classic example of a composite volcanic cone.

Historically, the eruptions of the volcano have fallen into a definite cyclical pattern with periods of activity, each lasting about 50 years, interspersed with periods of dormancy. The first cycle of activity (after the Spanish arrived in Mexico) was between 1576 and 1611. Major eruptions occurred in 1680 and 1690, and further complete cycles occurred between 1749 and 1818, and from 1869 to 1913. Most geologists agree that current activity is part of the fifth cycle, which began in 1961.

A three year sequence of prior activity (2003 to 2005) is shown on this series of NASA satellite images.

Hazard Map of Colima Volcano (2003) Credit: Universidad de Colima, Observatorio Vulcanológico

Hazard Map of Colima Volcano (2003) Credit: Universidad de Colima, Observatorio Vulcanológico. Click for full-size image (large file size)

In each major cycle, the first results of renewed activity force new lava into the existing crater, forming a dome. Once the crater has filled up, any additional lava is ejected from the crater and flows down the volcano’s flanks. If the lava is unable to escape (relieving the underground pressure), the dome is liable to explode, which is exactly what happened a few days ago:

As on several previous occasions, once the subterranean pressure that caused the activity has been relieved, activity should cease, and the volcano will enter another less dangerous dormant phase. Even during this phase, a plume of hot gas often billows out from the volcano.

The dome that was destroyed in January 2013 began to build in 2007. The explosive activity on 6 January and 10 January 2013 left behind a new crater 220 meters (720 ft) across and about 50 m (165 ft) deep. According to the Jalisco-Colima Scientific Committee (which oversees the hazard analysis posed by the volcano), the events of 6 and 10 January emitted an estimated  1.5 million cubic meters of material, which formerly formed the dome. The 10 January explosion, which occurred at 21:40 hrs local time, sent incandescent material down the west flank of the volcano. An ash column rose about 3000 meters into the air before traveling north-eastwards on the wind towards the city of Ciudad Guzmán.

Thermal imaging shortly after the 10 January explosion showed that the temperatures in the crater are below 200 degrees Centigrade, which indicates relatively little gaseous build up and limited risk of further major explosions. Even so, a prudent 7.5 km exclusion zone is being maintained around the volcano.

Update (29 Jan 2013):

Another explosion at 3:58 am on 29 January 2013 created a plume of ash and cinders that rose more than 3000 meters above the volcano. The ash fell of nearby villages, including Los Mazos, Ejido Atenquique, Tuxpan and Huescalapa.

The area around the volcanoes is described in more detail in chapter 15 of “Western Mexico, a Traveler’s Treasury” (4th edition; Sombrero Books, 2013).

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The Teziutlán disaster of 5 October 1999, a case study of vulnerability

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Oct 042012
 

Today marks the 13th anniversary of a major disaster that struck Teziutlán (current population about 65,000), a small city in the Eastern Sierra Madre, in the northeast corner of the state of Puebla, close to the border with Veracruz. The city is noteworthy as the birthplace of two prominent twentieth-century politicians: Manuel Ávila Camacho (served as President, 1940–1946) and Vicente Lombardo Toledano, who founded the Confederación de Trabajadores de México (CTM), Mexico’s largest confederation of labor unions.

The town’s name means “place of the hailstones”. But in 1999, it was not hailstones but torrential rain that triggered the major disaster of 4/5 October, with parts of the city destroyed by a series of landslides and mudflows. More than 80 municipalities were affected to some degree by this tremendous storm. Hundreds of landslides occurred in Hidalgo, Veracruz and Puebla states, causing an estimated US$457 million worth of damage, and at least 260 deaths.

This post focuses only on the consequences for Teziutlán where several hundred homes were completely destroyed and almost a thousand homes suffered partial damage. More than 100 Teziutlán residents lost their life. The local infrastructure, roads, housing, schools and farming were all severely impacted.

The worst damage was in the La Aurrora district on the eastern side of the city, where a landslide on a 23-degree slope buried more than 130 people. In another district, La Gloria, in the western part of the city, several more slips, flows and slides damaged homes, but without any fatalities.

With the benefit of hindsight, this disaster offers a good case study of the factors which made the inhabitants of Teziutlán particularly vulnerable to such an event. The diagram suggests one general classification of the multitude of factors that can affect vulnerability. In the case of Teziutlán, the discussion that follows suggests that the physical factors were probably the most significant.

factors affecting vulnerability

Factors affecting vulnerability (Geo-Mexico, Figure 7.2) All rights reserved.

Physical factors

1. Relief and geology. The area ranges in elevation from 300-2,280 meters above sea level and is drained by the El Calvario, Xóloatl and Xoloco rivers. The city is located at the southern limit of the Eastern Sierra Madre (Sierra Madre Oriental), very close to where it is truncated by the geologically more recent Volcanic Axis. The local geology includes a series of loosely compacted, pumice-rich pyroclastic flows, most of which are thought to be associated with the Los Humeros caldera. These deposits are interlaced with palaeosoils rich in clay which are impermeable and restrict the infiltration of rainwater, and overlie older folded rocks. The combination of steep slopes and impermeable, unconsolidated layers increases the risk of landslides and other forms of mass movement.

2. Climate.  This mountainous region is one of the most humid and foggiest in Mexico, averaging 280 days of mist or fog each year. Teziutlán has an average precipitation of 1600 mm/yr, though totals of over 2000mm are not that uncommon. Most rain falls between July and October.On 4 October 1999, a moist tropical depression off the coast of Veracruz was prevented from moving by a cold front. This led to an increase in humidity followed  by torrential downpours (over 300 mm of rain) over Teziutlán and the surrounding area. The storm continued the next day when a further 360 mm of rain fell.  The rain that fell on just those two days was equivalent to about 40% of Teziutlán’s usual total for an entire year.

3. Earthquake A few days prior to the storm, on 30 September 1999, a 7.4-magnitude earthquake occurred off the coast of Puerto Escondido (Oaxaca). This earthquake did cause  minor cracks in some homes in Teziutlán, and it possibly played a (minor) contributory role in the severity of the storm’s impacts.

Environmental

Deforestation, as a consequence of unplanned urban growth, was also important. Natural and secondary woodlands were steadily being cleared for construction and agriculture. This had an adverse effect on infiltration rates and the capacity of the land to absorb rainwater. However, given the extreme magnitude of the rainfall event, it is unlikely that the area would have escaped unscathed, even if the natural forest had remained.

In the La Aurrora district, where a landslide/mudflow buried more than 130 people, the construction of  a cemetery on a hill above La Aurrora may have played a part, since it appears that a cemetery wall held rainwater back, allowing more of it to seep into the underlying slope, increasing its susceptibility to a serious slide.

La Aurrora, October 1999. Credit: Periódico Sierra Norte

La Aurrora, October 1999. Credit: Periódico Sierra Norte

Educational

The town had suffered severe mass movements during prior storms. For example, in 1955, the rains that accompanied Hurricane Janet provoked numerous mass movements resulting in the disruption of transport systems, including the main highway, but with no loss of life. However, in general, it is clear that these prior events did not increase Teziutlán’s preparedness for a similar event in the future. In particular, prior events did not lead to building regulations being enforced or prevent buildings from being erected in high-risk areas.

Social/Demographic

In the period following the last major event (in 1955), the population of Teziutlán had increased rapidly, leading to the equally rapid expansion of the urban area. This was uncontrolled and included construction on steep slopes with insufficient attention to stability or possible mass movement mitigation measures being taken. It is worth noting that the population has continued to increase rapidly since the disaster, too.

Economic

Home owners in Mexico do not generally carry insurance on their properties, and even when they do, it often specifically excludes major meteorological events. It is unlikely that any of the residents of Teziutlán were able to make insurance claims. Many of the those affected would not have had savings and would have been forced to rely on family, friends and emergency hand-outs to survive. As a 1999 BBC News article emphasizes, government help was slow to arrive.

Want to see more?

There are several Youtube videos with images of the disaster. Perhaps the most interesting is TEZIUTLAN 1999 – 10 años Después del desastre  because it includes some clips from an investigative 1995 TV program aired in 1995 (four years prior to the landslide) that highlighted the extreme risk of constructing unauthorized buildings on the steep slopes of the town along the main highway. This video includes many excellent photos [warning: some graphic images] of the landslide and its aftermath, with a commentary [in Spanish].

Other valuable Youtube resources include Teziutlan Desastre 1999 which has additional photos, plus some eyewitness memories of the event [in Spanish], and TEZIUTLAN historia y tragedia which has many photos of the disaster, accompanied by music only (no commentary) making it a good choice for English-speaking classes.

Sources:

Alcántara-Ayala, I.  Flowing Mountains in Mexico. Mountain Research and Development, Vol 24, No. 1, Feb. 2004: 10-13.

Flores Lorenzo, Pablo & Irasema Alcántara Ayala. Cartografía morfogenética e identificación de procesos de ladera en Teziutlán, Puebla. Boletín del Instituto de Geografía, UNAM. #49, 2002, pp. 7-26. [pdf file]

 

Aug 022012
 

The rainy season is now well underway in most of Mexico, but large swathes of the north are still experiencing severe drought conditions. For example, the state of Zacatecas was recently officially declared a drought disaster zone. It is still too early to estimate the total economic impact of the drought, but the U.S. Department of Agriculture (USDA) has reported that the drought has already caused agricultural damages in Mexico of $1.2 billion dollars, in addition to the $8 billion dollars of losses for Texas.

The drought has raised many issues connected to trans-border water agreements and flows, with renewed calls for them to be formally reviewed and updated. Two examples should suffice to show the seriousness of the situation.

1. Under the terms of a 1906 bilateral treaty, Mexico is entitled to 74 million cubic meters from the Elephant Butte and Caballo reservoirs in New Mexico. However, according to Adolfo Mata, foreign affairs officer for the U.S. Section of the International Boundary and Water Commission (IBWC), the USA will only be able to deliver a maximum of 18.5 million cubic meters this year.

2. Meanwhile, south of the border, the governor of the state of Chihuahua has stated that his state is unable to meet its obligation to deliver water to the USA under the terms of a 1944 International Water Treaty between the two countries. He said that, “No one can give what they do not have. Chihuahua cannot meet this treaty, not for a lack of will, but because it has not rained,” adding that Chihuahua was the only desert in the world that was expected to export water. According to the governor, the treaty requires that about 80% of the rainfall that Chihuahua receives is exported.

On a more positive note, researchers at the Ibero-American University have announced the development of a hydrogel capable of absorbing 200 times its own weight of water before gradually releasing it. The hydrogel could be a useful additional to the range of drought mitigation measures available for farmers. Climate change scientists predict that northern Mexico will suffer from more frequent and more severe droughts in coming decades.

The hydrogel, which is expected to cost 800 pesos (60 dollars) a kilo when it comes on the market, is a mix of natural gelatine and polyacrylic_acid  Hydrogel can only be used in orchards or other areas where the soil remains undisturbed by regular plowing, so it will not help farmers growing corn or beans, for example. The hydrogel has been tested in citrus orchards in San Luis Potosí, and succeeded in halving the required frequency of irrigation from twice a week to once a week, saving water and reducing energy costs. Each citrus tree required a kilo of hydrogel each year.

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