Investigating the dynamics of an Alpine glacier using probabilistic icequake Locations: Triftgletscher, Switzerland

摘要: [1] In order to improve our understanding of the dynamics potentially unstable steep glacier tongues, we monitored during summer 2010 micro seismicity Triftgletscher, Switzerland. Our system, comprising 8 three‒component seismometers coupled with ice surface, was installed upstream glacier's tongue, which is likely evolve toward an regime. Complementary surface motion and proglacial runoff measurements allowed icequake activity be interpreted in terms hydraulics. The strong contrast seismic wave velocities due underlying bedrock taken into account using a three‒dimensional (3‒D) velocity model, implemented nonlinear probabilistic location procedure allowing accurately define hypocenter uncertainty. We located 120 icequakes, focal depth accuracy that distinguishing between shallow events (87 events) near‒bedrock icequakes (33 events). first motions most deep argue against pure shear sources expected case stick‒slip motion, suggested source mechanism superimposed tensile crack dislocation. analysis strain showed near‒surface represent opening transverse extension crevasses confluent flow