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Ocean-bottom seismology of glacial earthquakes; the concept, lessons learned, and mind the sediments

Evgeny A. Podolskiy, Yoshio Murai, Naoya Kanna and Shin Sugiyama
Ocean-bottom seismology of glacial earthquakes; the concept, lessons learned, and mind the sediments
Seismological Research Letters (May 2021) 92 (5): 2850-2865

Abstract

About 70% of Earth's surface is covered by ocean, for which seismic observations are challenging. Seafloor seismology overcame this fundamental difficulty and radically transformed the earth sciences, as it expanded the coverage of seismic networks and revealed otherwise inaccessible features. At the same time, there has been a recent increase in the number of studies on cryoseismology. These have yielded multiple discoveries but are limited primarily to land and ice-surface receivers. Near ice calving fronts, such surface stations are noisy, primarily due to crevassing and wind, are hazardous to maintain, and can be lost due to iceberg calving. To circumvent these issues, we have applied ocean-bottom seismology to the calving front of a tidewater glacier in northwest Greenland. We present details of this experiment, and describe the technical challenges, noise analysis, and examples of recorded data. This includes tide-modulated seismicity with thousands of icequakes per day and the first near-source ( approximately 200-640 m) underwater record of a major kilometer-scale calving event in Greenland, which generated a glacial earthquake that was detectable approximately 420 km away. We also identified a decrease in bottom-water temperature, presumably due to modified water stratification driven by extreme Greenland glacial melting, at the end of July 2019. Importantly, we identify glacial sediments as the key reason for the anomalously long ( approximately 9.7 hr) delay in the sensor release from the fjord seafloor. Our study demonstrates a methodology to undertake innovative, interdisciplinary, near-source studies on glacier basal sliding, calving, and marine-mammal vocalizations.


ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 92
Serial Issue: 5
Title: Ocean-bottom seismology of glacial earthquakes; the concept, lessons learned, and mind the sediments
Affiliation: Hokkaido University, Arctic Research Center, Hokkaido, Japan
Pages: 2850-2865
Published: 20210505
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 66
Accession Number: 2021-050535
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N60°00'00" - N84°00'00", W70°00'00" - W20°00'00"
Secondary Affiliation: University of Tokyo, Atmosphere and Ocean Research Institute, Kashiwa, JPN, Japan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202135
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