TY  - JOUR
A1  - Pirli, Myrto
A1  - Hainzl, Sebastian
A1  - Schweitzer, Johannes
A1  - Köhler, Andreas
A1  - Dahm, Torsten
T1  - Localised thickening and grounding of an Antarctic ice shelf from tidal triggering and sizing of cryoseismicity
JF  - Earth & planetary science letters
N2  - We observe remarkably periodic patterns of seismicity rates and magnitudes at the Fimbul Ice Shelf, East Antarctica, correlating with the cycles of the ocean tide. Our analysis covers 19 years of continuous seismic recordings from Antarctic broadband stations. Seismicity commences abruptly during austral summer 2011 at a location near the ocean front in a shallow water region. Dozens of highly repetitive events occur in semi-diurnal cycles, with magnitudes and rates fluctuating steadily with the tide. In contrast to the common unpredictability of earthquake magnitudes, the event magnitudes show deterministic trends within single cycles and strong correlations with spring tides and tide height. The events occur quasi-periodically and the highly constrained event sources migrate landwards during rising tide. We show that a simple, mechanical model can explain most of the observations. Our model assumes stick-slip motion on a patch of grounded ice shelf, which is forced by the variations of the ocean-tide height and ice flow. The well fitted observations give new insights into the general process of frictional triggering of earthquakes, while providing independent evidence of variations in ice shelf thickness and grounding.
KW  - tidally modulated cryogenic seismicity
KW  - stick-slip motion
KW  - event recurrence predictability
KW  - ice-shelf thickness
KW  - ice-shelf grounding
KW  - East Antarctica
Y1  - 2018
U6  - https://doi.org/10.1016/j.epsl.2018.09.024
SN  - 0012-821X
SN  - 1385-013X
VL  - 503
SP  - 78
EP  - 87
PB  - Elsevier
CY  - Amsterdam
ER  -