HR: 0800h
AN: V21D-0635    [Abstracts]
TI: Volcanic eruptions following mega-earthquakes of the 20th century and implications for the Sumatra-Andaman volcanoes
AU: * Walter, T R
EM: twalter@gfz-potsdam.de
AF: GFZ Potsdam Sektion 2.1, Telegrafenberg, Potsdam, 14473 Germany
AU: Amelung, F
EM: famelung@rsmas.miami.edu
AF: MGG-RSMAS Univ of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149 United States
AB: Two volcanic eruptions in the Sumatra-Andaman volcanic line following the 2004-2005 M9.3 and M8.7 earthquakes add evidence to the hypothesis that large earthquakes trigger volcanic eruptions. The eruptions appear to be encouraged by elastic stress transferred to the volcanic systems, yet the type of stress changes that encourage eruptions as well as the mechanisms of eruption triggering are not understood. Here we analyze eruptions in volcanic lines associated with the subduction zones of four mega-earthquakes (Kamchatka 1952, Chile 1960, Alaska 1964, Sumatra-Andaman 2004). We show that during these earthquakes numerous volcanoes experienced extensional strain. These volcanoes display also an abrupt increase of the eruption rate, most notably for the Mw 9.5 1960 Chile earthquake the largest-ever recorded earthquake. This study suggests that earthquake-induced extensional strain encourages eruptions. Possible mechanisms for eruption triggering include unclamping of the rock in the vicinity of the volcanic system facilitating dike propagation, bubble growth in magma chambers leading to the build-up of magma overpressure, and decompressional melting. The results of other mega-earthquakes imply an likely increase of eruptions at the Sumatra-Andaman volcanic line.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7280 Volcano seismology (8419)
DE: 8419 Volcano monitoring (7280)
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005