Coronavirus Information for the UC San Diego Community

Our leaders are working closely with federal and state officials to ensure your ongoing safety at the university. Stay up to date with the latest developments. Learn more.

Joint geodetic and seismic analysis of surface crevassing near a seasonal glacier-dammed lake at Gornergletscher, Switzerland

TitleJoint geodetic and seismic analysis of surface crevassing near a seasonal glacier-dammed lake at Gornergletscher, Switzerland
Publication TypeJournal Article
Year of Publication2019
AuthorsGarcia L, Luttrell K, Kilb D, Walter F
Pagination1-13
ISBN Number0260-3055
Keywordscrevasses; glacier flow; glacier geophysics; glaciological instruments and methods; Seismology
Abstract

Seasonal lake Gornersee forms at the confluence of Gornergletscher and Grenzgletscher, Switzerland, and experiences outburst floods annually in midsummer. To study the interplay between lake drainage, glacier movement and crevasse activity, high-frequency seismometers and GPS receivers were deployed in networks near Gornersee during the summer ablation seasons of 2004, 2006 and 2007. We use a Rayleigh wave coherence method to locate 3289, 7939 and 4087 icequakes, respectively, primarily along well-defined surface crevasses. We calculate two-dimensional strains from triads of GPS stations and find mean differential strain rates of ~300 × 10−6 d−1 with diurnal variations up to 800 × 10−6 d−1. Crevasse icequake activity and glacial velocity are highest during early season, then decrease as meltwater channels erode and subglacial water pressure decreases. Glacial response to Gornersee drainage varied year-to-year, with icequake activity promoted at some crevasses and inhibited at others, suggesting syn-drainage icequakes may be indicative of local drainage patterns and small-scale features of the stress field. Diurnal pulses in icequake activity exhibit peak activity at different times of day in different locations, coincident with a southeast-to-northwest trending concentrated shear zone near the Gornergletscher–Grenzgletscher confluence, likely due to differences in the timing of peak strain rate in these regions.

DOI10.1017/aog.2018.32
Student Publication: 
No
sharknado