Precursory seismicity associated with frequent, large ice avalanches on Iliamna Volcano, Alaska, USA

Journal of Glaciology
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Abstract

Since 1994, at least six major (volume>106 m3) ice and rock avalanches have occurred on Iliamna volcano, Alaska, USA. Each of the avalanches was preceded by up to 2 hours of seismicity believed to represent the initial stages of failure. Each seismic sequence begins with a series of repeating earthquakes thought to represent slip on an ice-rock interface, or between layers of ice. This stage is followed by a prolonged period of continuous ground-shaking that reflects constant slip accommodated by deformation at the glacier base. Finally the glacier fails in a large avalanche. Some of the events appear to have entrained large amounts of rock, while others comprise mostly snow and ice. Several avalanches initiated from the same source region, suggesting that this part of the volcano is particularly susceptible to failure, possibly due to the presence of nearby fumaroles. Although thermal conditions at the time of failure are not well constrained, it is likely that geothermal energy causes melting at the glacier base, promoting slip and culminating in failure. The frequent nature and predictable failure sequence of Iliamna avalanches makes the volcano an excellent laboratory for the study of ice avalanches. The prolonged nature of the seismic signal suggests that warning may one day be given for similar events occurring in populated regions.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Precursory seismicity associated with frequent, large ice avalanches on Iliamna Volcano, Alaska, USA
Series title Journal of Glaciology
DOI 10.3189/172756507781833866
Volume 53
Issue 180
Year Published 2007
Language English
Publisher Cambridge Journals
Contributing office(s) Volcano Hazards Program
Description 13 p.
First page 128
Last page 140
Country United States
State Alaska
Other Geospatial Mount Iliamna
Online Only (Y/N) N
Additional Online Files (Y/N) N
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