期刊
JOURNAL OF GLACIOLOGY
卷 67, 期 261, 页码 58-74出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/jog.2020.83
关键词
Glacier geophysics; ice shelves; seismology
资金
- NSF [PLR-1142518, 1141916, 1142126, 1246151, 1246416, OPP-1744852, 1744856]
- National Science Foundation [EAR-1851048]
- DOE National Nuclear Security Administration
- Office of Polar Programs (OPP)
- Directorate For Geosciences [1246416] Funding Source: National Science Foundation
- Office of Polar Programs (OPP)
- Directorate For Geosciences [1246151, 1141916, 1142126, 1744856] Funding Source: National Science Foundation
Observations of teleseismic earthquakes using broadband seismometers on the Ross Ice Shelf reveal seasonal and geographic variations in signal-to-noise ratios, accurate estimation of ice and water layer thicknesses, and observations consistent with theoretically predicted phenomena, suggesting that teleseismic coda can be utilized for passive imaging of sub-shelf Earth structure.
Observations of teleseismic earthquakes using broadband seismometers on the Ross Ice Shelf (RIS) must contend with environmental and structural processes that do not exist for land-sited seismometers. Important considerations are: (1) a broadband, multi-mode ambient wavefield excited by ocean gravity wave interactions with the ice shelf; (2) body wave reverberations produced by seismic impedance contrasts at the ice/water and water/seafloor interfaces and (3) decoupling of the solid Earth horizontal wavefield by the sub-shelf water column. We analyze seasonal and geographic variations in signal-to-noise ratios for teleseismic P-wave (0.5-2.0 s), S-wave (10-15 s) and surface wave (13-25 s) arrivals relative to the RIS noise field. We use ice and water layer reverberations generated by teleseismic P-waves to accurately estimate the sub-station thicknesses of these layers. We present observations consistent with the theoretically predicted transition of the water column from compressible to incompressible mechanics, relevant for vertically incident solid Earth waves with periods longer than 3 s. Finally, we observe symmetric-mode Lamb waves generated by teleseismic S-waves incident on the grounding zones. Despite their complexity, we conclude that teleseismic coda can be utilized for passive imaging of sub-shelf Earth structure, although longer deployments relative to conventional land-sited seismometers will be necessary to acquire adequate data.
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