Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4715348 | Journal of Volcanology and Geothermal Research | 2006 | 8 Pages |
We review the different phases of the seismicity related to the 1982 eruption of El Chichon Volcano, Chiapas, Mexico. The pre-eruption seismicity was already anomalous by late 1980, became significant by late 1981 and increased towards 28 March, 1982, when the first eruptive event occurred. A noticeable feature within the 7-day period of unrest is the occurrence of three earthquake swarms before the devastating explosions of 3 and 4 April 1982 (local time). The periodicity and appearance of the swarms, close to the time of maximum tidal strain, suggests a large overpressure in the magmatic system, and the triggering of the events by the earth tides. The post-eruption seismicity occurred mostly in a radius 5 km from the crater and a depth range 11 to 15 km suggesting that this region was a deeper reservoir of the erupted magma.