Chaitén Volcano | John Seach


Patagonia, Chile

42.833 S, 72.646 W
summit elevation 962 m

John Seach was the first scientist to climb to the summit of Chaiten volcano during the 2008 eruption. This was the largest Ryolite eruption on earth in 100 years. John made two expeditions to Chaiten volcano in 2008.

Chaiten volcano is located in southern Chile, 10 km NE of the town of Chaitén on the Gulf of Corcovado. The volcano contains an obsidian lava dome in a 3.5 km wide caldera. The volcano is occasionally covered with snow, but does not contain a glacier. Two small lakes occupy the caldera floor on the west and north sides of the lava dome. The 2008 Chaiten eruption was the first explosive Rhyolite eruption to be scientifically studied.

Chaiten volcano photos by John Seach

John Seach climbing to the summit of Chaiten volcano August 2008.

chaiten volcano chile 2008
Climbing Chaiten volcano in August 2008. John Seach was first scientist
to summit during the eruption.

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Chaiten summit crater, August 2008

chaiten volcano summit
John Seach at Chaiten volcano summit August 2008

chaiten volcano 2008
Chaiten 2008

chaiten volcano
John Seach at Chaitén town in July 2008

chaiten 2008
Chaiten, August 2008 looking towards volcano

School damaged by lahars in Chaiten town - John Seach

chaiten town
Lahar damage, Chaiten town - John Seach

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Chaiten disaster 2008

chaiten eruption 2008
Chaiten town during 2008 eruption

Video: John Seach at Chaiten volcano, 2008.  

The eruption of Chaiten volcano was considered to be tectonically controlled. It was possibly caused by the Aisén Fjord earthquake (Mag 6.2) which occurred 250 km south of Chaiten on 21st April 2007.

The volcano erupted on 2nd May 2008. Ash emissions reached a height of 30 km (100,000 ft) on 6th May. More than 4000 people were evacuated from nearby villages and the town of Chaiten, 10 km from the volcano, and Futaleufu 70 km southeast. This was the first historical eruption at the volcano. The previous dated eruption was over 9000 years ago. The eruption was possibly triggered by tectonic shifts that opened tear faults and promote magma to rise to the surface.

During a visit to Chaitén volcano in Chile on 9th July, John Seach observed lahar destruction of the town, and ashfall damage to surrounding areas, and pyroclastic flow devastation on the north flank of the volcano. On the north side of the volcano at a location 3 km from the crater, an area of devastated forest was visited. Plinian eruptions, and pyroclastic flows, burnt forest and stripped trees of foliage. An area of 10 sq km on the north side of the crater was completely devoid of vegetation, except for some standing devastated trees. Trees up to a meter in diameter were snapped off at a height of 4 m. Fire had burnt the entire area. The field area consisted of a mixture of standing devastated trees, fallen trees, and deep ash deposits. A sharp distinction was observed between areas of devastated forest and standing untouched forest. Continuous ash fall occurred in Chaitén town. Lahars were reaching the town once per week. Residents were allowed into the town to evacuate possessions and begin the clean up. Residents reported hearing rumbling noises under the town, similar to the sound of running water.

In August 2008 John Seach was the first scientist to climb to summit of Chaiten volcano after the worlds largest rhyolite eruption in 100 years. The summit crater contained a 120 m high lava dome. Earthquakes were felt at the summit. The lava dome was loudly degassing, and lava boulders avalanched from the dome side to the crater floor.

More on Chaiten eruptions...

Further reading
Lara, L.E., Moreno, R., Amigo, ┴., Hoblitt, R.P. and Pierson, T.C., 2013. Late Holocene history of Chaitén Volcano: New evidence for a 17th century eruption. Andean Geology, 40(2), pp.249-261.

Castro, J.M. and Dingwell, D.B., 2009. Rapid ascent of rhyolitic magma at Chaitén volcano, Chile. Nature, 461(7265), pp.780-783.

Lara, L.E., 2009. The 2008 eruption of the Chaitén Volcano, Chile: a preliminary report. Andean geology36(1), pp.125-129.

Carn, S.A., Pallister, J.S., Lara, L., Ewert, J.W., Watt, S., Prata, A.J., Thomas, R.J. and Villarosa, G., 2009. The unexpected awakening of Chaitén volcano, Chile. Eos, Transactions American Geophysical Union90(24), pp.205-206.

Chaitén Volcano Eruptions

2008-10, 7420 BC ± 75