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Modeling the dynamic response of a crater glacier to lava-dome emplacement: Mount St Helens, Washington, USA

Annals of Glaciology
By:  and 
https://doi.org/10.3189/172756407782282525

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Abstract

The debris-rich glacier that grew in the crater of Mount St Helens after the volcano's cataclysmic 1980 eruption was split in two by a new lava dome in 2004. For nearly six months, the eastern part of the glacier was squeezed against the crater wall as the lava dome expanded. Glacier thickness nearly doubled locally and surface speed increased substantially. As squeezing slowed and then stopped, surface speed fell and ice was redistributed downglacier. This sequence of events, which amounts to a field-scale experiment on the deformation of debris-rich ice at high strain rates, was interpreted using a two-dimensional flowband model. The best match between modeled and observed glacier surface motion, both vertical and horizontal, requires ice that is about 5 times stiffer and 1.2 times denser than normal, temperate ice. Results also indicate that lateral squeezing, and by inference lava-dome growth adjacent to the glacier, likely slowed over a period of about 30 days rather than stopping abruptly. This finding is supported by geodetic data documenting dome growth.

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Publication type Article
Publication Subtype Journal Article
Title Modeling the dynamic response of a crater glacier to lava-dome emplacement: Mount St Helens, Washington, USA
Series title Annals of Glaciology
DOI 10.3189/172756407782282525
Volume 45
Year Published 2007
Language English
Publisher International Glaciological Society
Publisher location Cambridge, United Kingdom
Contributing office(s) Volcano Hazards Program
Description 8 p.
First page 21
Last page 28
Country United States
State Washington
County Skamania County
Online Only (Y/N) N
Additional Online Files (Y/N) N
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