El Chichón's "surprise" eruption in 1982: lessons for reducing volcano risk

Abstract

During one week (28 March–4 April 1982), three powerful explosive eruptions (VEI 5) of El Chichón Volcano caused the worst volcanic disaster in Mexico's recorded history. Pyroclastic flows and surges obliterated nine villages, killing about 2,000 people, and ashfalls downwind posed socio–economic hardships for many thousands of inhabitants of the States of Chiapas and Tabasco. The unexpected and vigorous eruption of 28 caused a hasty, confused evacuation of most villagers in the area. Activity was greatly diminished the next five days, and then the most powerful and lethal eruptions occurred 3–4 April—tragically, after many evacuees were allowed by authorities to return home. Unfortunately, the eruptions came as an almost total surprise for scientists and government authorities, effectively precluding opportunities to implement timely mitigative countermeasures. During the months before eruption onset, fumarolic activity increased and inhabitants living close to the volcano felt occasional earthquakes, prompting the Chiapas government to request help from the Federal government. Both the Chiapas and Federal governmental actions were slow, and the requested assistance came after the volcano erupted. Perhaps the most important lesson learned from the disastrous outcome at El Chichón is that its decreased activity (29 March–2 April) should not have been assumed by the senior scientist on site—and the military authorities acting on his advice—to signal the end of eruption. While the 1982 eruptions caused a national tragedy, they also fostered multidisciplinary studies of eruptive phenomena, not only at El Chichón but also other explosive volcanoes in the world.