Discrete and tremor seismicity near a microseismic stick-slip asperity at the base of an Alpine glacier ...

• Main Author: Köpfli, Manuela
• Format: Text
• Language: English
• Published: ETH Zurich 2021
• Subjects: Ice Sheet
• Online Access: https://dx.doi.org/10.3929/ethz-b-000544060; http://hdl.handle.net/20.500.11850/544060

Frictional resistance at the base of glacial ice controls ice sheet dynamics but is still incompletely understood. While basal sliding theories are traditionally based on slow and smooth sliding on a friction-less bed caused by viscous creep and regelation, frictional sliding at distinct patches of the glacier bed ('asperities') may also play a significant role. With the help of a dense borehole seismometer network within 30\,m of an active microseismic stick-slip asperity at the glacier bed of Rhonegletscher, I collected a novel data set. This data set makes it possible to gain a detailed view on frictional processes, that resist smooth sliding and lead to episodic stress release at the glacier bed. The high spatial and temporal resolution of the seismic array helps to investigate basal sliding from a new perspective. I locate distinct basal stick-slip events with phase arrivals and successive events (basal stick-slip sliding tremor) with amplitude source location. Location with the double-difference method ...