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.
The Journal of Glaciology is published six times per year. It accepts submissions from any discipline related to the study of snow and ice. All articles are peer reviewed. The Journal is included in the ISI Science Citation Index.