Seismic Evidence for Discrete Glacier Motion at the Rock–Ice Interface

• Published in: Journal of Glaciology
• Main Authors: Weaver, Craig S., Malone, Stephen D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1979
• Subjects: Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000029816; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000029816

Abstract Seismic monitoring on three Cascade volcanoes in Washington State, U.S.A., has shown that small seismic events are generated by the active glaciers found on each mountain. Detailed seismic experiments have been conducted to investigate the sources for these icequakes. Considerable evidence indicates that the events are the result of a stick–slip type of motion taking place at the bed of the glaciers. The few events we have been able to locate had depths comparable with the glaciers’ thickness. The similarity of wave form from an explosion at the bottom of a glacier and natural icequakes suggests that the complexity of the seismic wave form is due to the path and not the source. The events exhibit an annual trend with more events being recorded in the summer than during the winter. A ten-fold increase in the number of events preceded a large ice avalanche that involved the entire glacier thickness, suggesting that seismic monitoring may be useful in predicting catastrophic ice movements.