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Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift
Author(s) -
Olinger S. D.,
Lipovsky B. P.,
Wiens D. A.,
Aster R. C.,
Bromirski P. D.,
Chen Z.,
Gerstoft P.,
Nyblade A. A.,
Stephen R. A.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl082842
Subject(s) - geology , induced seismicity , rift , seismology , seismometer , ice shelf , geophysics , oceanography , tectonics , sea ice , cryosphere
Understanding deformation in ice shelves is necessary to evaluate the response of ice shelves to thinning. We study microseismicity associated with ice shelf deformation using nine broadband seismographs deployed near a rift on the Ross Ice Shelf. From December 2014 to November 2016, we detect 5,948 icequakes generated by rift deformation. Locations were determined for 2,515 events using a least squares grid‐search and double‐difference algorithms. Ocean swell, infragravity waves, and a significant tsunami arrival do not affect seismicity. Instead, seismicity correlates with tidal phase on diurnal time scales and inversely correlates with air temperature on multiday and seasonal time scales. Spatial variability in tidal elevation tilts the ice shelf, and seismicity is concentrated while the shelf slopes downward toward the ice front. During especially cold periods, thermal stress and embrittlement enhance fracture along the rift. We propose that thermal stress and tidally driven gravitational stress produce rift seismicity with peak activity in the winter.