Title Icequakes coupled with surface displacements for predicting glacier break- off
Author Faillettaz, J.; Funk, M.; Sornette, D.
Author Affil Faillettaz, J., ETH Zurich, Labortory of Hydraulics, Hydrology and Glaciology, Zurich, Switzerland
Source Journal of Glaciology, 57(203), p.453- 460, . Publisher: International Glaciological Society, Cambridge, United Kingdom. ISSN: 0022-1430
Publication Date 2011
Notes In English. 45 refs. GeoRef Acc. No: 310271
Index Terms elastic waves; glacial geology; glaciers; ice; ice mechanics; icequakes; Switzerland--Valais; Central Europe; Europe; glaciotectonics; seismic waves; seismicity; Switzerland; Valais Switzerland; Weisshorn
Abstract A hanging glacier at the east face of Weisshorn, Switzerland, broke off in 2005. We were able to monitor and measure surface motion and icequake activity for 25 days up to 3 days prior to the break-off. The analysis of seismic waves generated by the glacier during the rupture maturation process revealed four types of precursory signals of the imminent catastrophic rupture: (1) an increase in seismic activity within the glacier; (2) a change in the size-frequency distribution of icequake energy; (3) a modification in the structure of the waiting- time distributions between two successive icequakes; and (4) a correlation between the seismic activity and the log-periodic oscillations of the surface velocities superimposed on the global acceleration of the glacier during the rupture maturation. Analysis of the seismic activity led us to identify two regimes: a stable phase with diffuse damage and an unstable and dangerous phase characterized by a hierarchical cascade of rupture instabilities where large icequakes are triggered.
URL http://hdl.handle.net/10.3189/002214311796905668
Publication Type journal article
Record ID 65007289