Seismic activity and surface motion of a steep temperate glacier: a study on Triftgletscher, Switzerland

Dalban Canassy, Pierre; Faillettaz, Jérome; Walter, Fabian; Huss, Matthias

doi:10.3189/2012JoG11J104

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Journal article

Seismic activity and surface motion of a steep temperate glacier: a study on Triftgletscher, Switzerland

Dalban Canassy, Pierre Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Switzerland
Faillettaz, Jérome Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Switzerland
Walter, Fabian Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Switzerland - Swiss Seismological Service (SED), ETH Zürich, Switzerland
Huss, Matthias Department of Geosciences, University of Fribourg, Switzerland

01.06.2012

Published in:

Journal of Glaciology. - 2012, vol. 58, no. 209, p. 513-528

English The tongue of Triftgletscher, Switzerland, is particularly susceptible to major break-off events due to its steep slope. In order to detect precursors of such an event, we monitored the local seismic activity and detected 2426 icequakes with sources located in an area ranging between 2050 and 2350 m a.s.l. Events triggered by cracks and icefalls were recorded, but no precise distinction between the two sources was possible using duration or frequency criteria. Clusters of seismic activity were located and confirmed by visual observations. We performed a surface motion analysis and found that surface motion was driven significantly by runoff changes at a timescale of 2-3 days. By means of a statistical analysis, a power-law behaviour of the released seismic energy distribution was discerned at certain times during the period investigated. Variations in power-law exponent values indicated that low- and high-energy events predominantly occurred during phases of enhanced and reduced surface motion, respectively. Substantial releases of seismic energy likely to signal the glacier recoupling were detected during phases of decreasing runoff. Clues to potential seismic precursors of break-off events are discussed.

Faculty

Faculté des sciences et de médecine

Department

Département de Géosciences

Language