El Chichón
| El Chichón | ||
|---|---|---|
 El Chichón, November 4, 1982 |
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| height |
1060 m (before volcanic eruption 1230 m ) |
|
| location | Mexico | |
| Coordinates | 17 ° 21 '36 " N , 93 ° 13' 40" W | |
|
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| Type | Lava dome | |
| Age of the rock | 220,000 years | |
| Last eruption | 1982 | |
The El Chichón , including El Chichonal , is a volcano in northwestern Chiapas , Mexico . He is the youngest volcano in the northwestern part of the 150-kilometer Chiapanikanischen volcanic arc (Chiapanecan Volcanic Arc, CVA).
There have been at least twelve eruptions in the past 8,000 years , with the last occurring in 1982. On three days - March 29th and April 3rd and 4th - around 7 million tons of sulfur dioxide and a total of 20 million tons of material were hurled into the stratosphere in Plinian eruptions . The mountain lost about 200 meters in height and a caldera with a diameter of one kilometer and an acidic crater lake formed inside. Around 2,000 people were killed in the outbreak.
Before the outbreak
Before the 1982 eruption, El Chichón was a Somma volcano , around 200,000 years old, with a central lava dome . This reached a height of 1,230 meters. The relative height to the surroundings was between 700 and 900 meters.
The 1982 eruption
The eruption had been preceded by fumarolic and seismic activity since 1980 . The tremors peaked in March 1982. The eruption began on the night of March 28-29. A crater 150 to 180 meters further opened at the central lava dome and a Plinian column rose 27 km into the atmosphere. On the morning of March 29, ash rain fell over the area and several thousand people were evacuated. However, by April 3, activities had declined to the point where the military allowed residents to return to their villages.
On the night of April 3rd to 4th, there was another increase and the peak of volcanic activity. Contact of the magma with groundwater resulted in a series of violent phreatic eruptions , pyroclastic pressure waves reached a radius of 8 km around the crater. Nine villages, including Francisco León , were destroyed and around 2,000 people were killed. The original lava dome was completely destroyed. On the evening of April 4, there was a final eruption, which again produced a 29 km high Plinian column.
The pyroclastic flows dammed several rivers, including the Magdalena with a dam up to 75 meters thick to a 4 km long lake of almost boiling water. The Susnubac river and the rains in April and May filled the lake with 40 million m³ of water. On May 26, the dam broke and the debris flow filled the valley of the Magdalena, destroying the previously evacuated village of Ostuacán . The water still had a temperature of 82 ° C 10 km below the dam. A worker was killed at a dam further downstream.
The eruption of El Chichón was one of the largest in the 20th century , totaling 1.5 km³ of magma , and the amount of material released into the stratosphere was only surpassed by that of Pinatubo in 1991. The resulting aerosol cloud orbited the earth in three weeks and spread over the next six months from the equator to the 30th parallel north. It is believed that this lowered the temperature of the atmosphere by at least 0.2 ° C and diminished the effect of a very strong El Niño that year.
After the outbreak
In 2000, the temperature of the crater lake rose, indicating rising lava .
In the meantime, activities of the volcano could be dated back to the time between 1350 and 1400. There have been at least twelve eruptions in the past 8,000 years, and every 100 to 600 years for the past 4,000 years.
Individual evidence
- ↑ El Chichon eruption - April 1982, Mexico (inTERRAgate) ( Memento of the original from January 9, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English)
Web links
- El Chichòn Volcano, 25th anniversary, A Commemorative Conference. (PDF) Universidad Nacional Autónoma de México , March 2007, accessed on November 22, 2009 .
- El Chichón in the Global Volcanism Program of the Smithsonian Institution (English)
- El Chichón at Volcano World (English)
- Alan Robock: Volcanic Eruption, El Chichón. (PDF; 28 kB) 2002, accessed on November 22, 2009 (English).