El Chichón

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El Chichón

Aerial view on 1982-11-04, seven months after the eruption
Elevation ~ 1,205 metres (3,953 ft)
Location
El Chichón
Francisco León, Chiapas, Mexico
Coordinates 17°21′36″N 93°13′40″W / 17.36000°N 93.22778°W / 17.36000; -93.22778Coordinates: 17°21′36″N 93°13′40″W / 17.36000°N 93.22778°W / 17.36000; -93.22778
Geology
Type Lava domes
Age of rock 220,000 yr
Volcanic arc/belt Chiapanecan Volcanic Arc
Last eruption 1982

El Chichón, also known as Chichonal, is an active volcano in Francisco León, north-western Chiapas, Mexico. El Chichón is part of a geologic zone known as the Chiapanecan Volcanic Arc. El Chichón is a complex of domes with a tuff ring, made of ejected volcanic material, located between the Trans Mexican Volcanic Belt and the Guatemalan Belt.[1] El Chichón erupted in 1982; prior to this, activity had not occurred since ca.1360, although debates in literature occur around an eruption occurring in ca.1850.[2]

El Chichón became famous for its 1982 eruption. In little under a week, the presumed dormant volcano produced three plinian eruptions (March 29, April 3, and April 4th).[2] The eruptions generated a substantial amount of sulphur dioxide and particulates into the atmosphere. The total volume of the eruption was much smaller than the famous eruption of Pinatubo in 1991; however El Chichón's impacts were equally as significant on global climate.[3] El Chichón is often overlooked in comparison to other historic eruptions, yet the 1982 eruptions provide important lessons on preparation for volcanic disasters and the influence volcanoes can have on climate.

1982 Eruption

The 1982 eruption of El Chichón is the largest volcanic disaster in modern Mexican history.[2] The powerful 1982 explosive eruptions of high-sulphur, anhydrite-bearing magma destroyed the summit lava dome and were accompanied by pyroclastic flows and surges that devastated an area extending about 8 km around the volcano.[4] A total of 9 villages were completely destroyed, killing 2000 people.[2] A new 1-km-wide, 300-m-deep crater was created that now contains an acidic crater lake.[4] The landscape was covered in ash up to 40 cm in depth.[4] Over 24,000 km2 of countryside was affected,[4] devastating coffee, cocoa, banana crops, and cattle ranches. The eruption caused natural dams to form along the Rio Magdalena river, inducing lahars, which destroyed key infrastructure. The total damage caused by the 1982 eruption is believed to amount to $55 million[2] (equivalent to $132 million in present day US dollars).

Lack of preparation

With more than 600 years since the last major eruption of El Chichón, few people were aware of the volcanic risk. Most presumed it to be a dormant volcano or extinct. Throughout 1980 and 1981 earthquakes were felt in the surrounding regions, and geologists hazard mapped the region highlighting risks, however no increases were seen in monitoring activity.[2]

Climate Impacts

The eruption injected 7 million metric tonnes of sulphur dioxide [5](SO2) and 20 million metric tonnes[5] total of particulate material into the stratosphere, which circulated the Earth in three weeks.[1] The eruption occurred just as the largest El Niño of the century was initiating; because of this several scientists suggested that the El Chichón eruption caused the El Niño.[5] However, climate modeling and detailed studies of past eruptions and El Niño have shown that there are no plausible theories connecting these two events, and that the timing was merely a coincidence.[5] As a result of the simultaneous eruption and El Niño, the climate felt the impacts of both, making it challenging to separate their effects on temperature.[5] Generally a volcanic event would induce global cooling, particularly in summer months, however no cooling was seen in the first year after the El Chichón eruption, because the El Niño produced large compensating warming.[3] The climatic effects also triggered winter warming patterns observed within northern hemisphere continents in 1982 and 1983, with temperatures increasing over North America, Europe, and Siberia. During the same winter, Alaska, Greenland, the Middle East, and China witnessed colder temperatures than normal, highlighting regional variation.[5] The variation is said to be a result of volcanic aerosols impact on the atmospheric wind patterns, including the Arctic Oscillation.[5]

See also

References

[6]

  1. ↑ 1.0 1.1 Alan Robock (2002). "Volcanic Eruption, El Chichón" (PDF). Retrieved 2008-05-20. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Wired Science (2012) Looking Back at the 1982 eruption of El Chichon in Mexico. Available at: http://www.wired.com/wiredscience/2012/03/looking-back-at-the-1982-eruption-of-el-chichon-in-mexico/ (Accessed: 08/10/2013)
  3. ↑ 3.0 3.1 Robock, A. (2000). Volcanic eruptions and climate. Reviews of Geophysics, 38(2), 191-219
  4. ↑ 4.0 4.1 4.2 4.3 Francis, P., and Oppenheimer, C., 2004, Volcanoes, Oxford University Press, 521pp
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Robock, A. (2013). Climate model simulations of the effects of the El Chichón eruption. Geofísica Internacional, 23(3)
  6. ↑ Báez-Jorge, F (1985). Cuando el cielo ardió y se quemó la tierra. Mexico: Instituto Nacional Indigenista. p. 158. ISBN 9688220558. 

External links

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