El Chichón, México

Volcano Type:      Lava domes
Volcano Status:    Historical
Last Known Eruption:     1982
Summit Elevation:     1150? m     3,773 feet
Latitude:     17.360°N     17°21’36″N
Longitude:     93.228°W     93°13’40″W

El Chichón is a small, but powerful trachyandesitic tuff cone and lava dome complex that occupies an isolated part of the Chiapas region in SE México far from other Holocene volcanoes. Prior to 1982, this relatively unknown volcano was heavily forested and of no greater height than adjacent nonvolcanic peaks. The largest dome, the former summit of the volcano, was constructed within a 1.6 x 2 km summit crater created about 220,000 years ago. Two other large craters are located on the SW and SE flanks; a lava dome fills the SW crater, and an older dome is located on the NW flank. More than ten large explosive eruptions have occurred since the mid-Holocene. The powerful 1982 explosive eruptions of high-sulfur, 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. The eruptions created a new 1-km-wide, 300-m-deep crater that now contains an acidic crater lake.

El Chichón

El Chichon is the most southern and eastern volcano in Mexico. It is a small, but powerful andesitic tuff cone and lava dome complex that occupies an isolated part of the Chiapas region far from other Holocene volcanoes. Prior to 1982, this relatively unknown volcano was heavily forested and of no greater height than adjacent non-volcanic peaks. The largest dome, the former summit of the volcano, was constructed within a 1.6 x 2 kilometer summit crater, created about 200,000 years ago.

Crater Lake

Two other large craters are located on the SW and SE flanks. More than a half dozen large explosive eruptions have occurred since the mid-Holocene. The powerful 1982 explosive eruptions of high-sulfur, anhydrite-bearing magma were accompanied by devastating pyroclastic flows and surges and destroyed the summit lava dome.  The eruptions created a new 1-kilometer-wide crater that now contains an acidic crater lake. El Chichon might have erupted from about 270 CE and every 500 to 600 year since, in about 700, 1350 and 1850, with explosive eruptions followed by pyroclastic flows. Then suddenly in 1982 it woke up again, way out of schedule. Prior to 1982, it was thought to be extinct. Consequently, activity of the volcano was not being monitored and the 1982 eruption was a total surprise (although, with hindsight, local inhabitants had noticed increased earthquake activity for some months prior to the first eruption).

Originally posted 2010-08-22 04:15:51.