El Chichón

El Chichón, November 4, 1982

The El Chichón, also 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).

In the last 8,000 years, there have been at least twelve eruptions, the last one took place in 1982. In this in three days - March 29 and the April 3 and 4 - around 7 million tons of sulfur dioxide and 20 million tons of material thrown at Plinian eruptions into the stratosphere. The mountain lost about 200 meters in height and formed a caldera with a kilometers in diameter and an acidic crater lake inside. Around 2,000 people died in the eruption killed.

Prior to the outbreak

Before the outbreak of the 1982 El Chichón a Somma volcano was about 200,000 years old, with a central lava dome. This reached a height of 1,230 meters. The relative height to the environment was between 700 and 900 meters.

The outbreak of 1982

The eruption was preceded since 1980 fumarolic and seismic activity. The tremors peaked in March 1982. The eruption began on the night of 28 to March 29. A 150 to 180 meters craters opened on the central lava dome and a Plinian column rose 27 km into the atmosphere. On the morning of March 29 went ash rain down on the area and several thousand people were evacuated. However, went to April 3, the activities so far back that the military allowed the residents to return to their villages.

On the night of 3 to 4 April, there was a resurgence and the height of the volcanic activity. By contact of magma with ground water, there was a series of violent phreatic eruptions, pyroclastic blasts hit a 8 km radius around the crater. In this nine villages, including Francisco Leon, destroyed and killed around 2,000 people. The original lava dome was completely destroyed. On the evening of 4 April it came to a final eruption that produced a 29 km high Plinian column again.

The pyroclastic flows dammed several rivers, including the Magdalena with an up to 75 m thick embankment to a 4 -kilometer-long lake from almost boiling water. The river Susnubac and the rains of April and May filled the lake with 40 million cubic meters of water. On May 26, the dam broke and the debris flow filled the valley of the Magdalena, the previously evacuated village Ostuacan was destroyed. Need 10 km below the dam the water had a temperature of 82 ° C. In an under construction dam, further downstream, a worker was killed.

The eruption of El Chichón was one of the largest in the 20th century, a total of 1.5 km ³ of magma were ejected, and it was surpassed in the amount of material introduced into the stratosphere only by the Pinatubo 1991. The resulting aerosol cloud orbited the Earth in three weeks, and spread out over the next six months from the Equator to 30 north latitude. It is believed that the lowered by at least 0.2 ° C, the temperature of the atmosphere and has reduced the effect of a very strong El Niño this year.

After the outbreak

In 2000, the temperature of the crater lake rose, indicating rising lava.

Meanwhile, activities of the volcano could be dated back to the time of 1350-1400. In the last 8,000 years, there have been at least twelve eruptions in the last 4,000 years, every 100 to 600 years.