[A-CG39] 北極域の科学

[ACG39-15] Glacier and whale monitoring with an Ocean-Bottom Seismometer at the calving front

*Evgeny A. Podolskiy¹、Yoshio Murai²、Naoya Kanna³、Shin Sugiyama⁴ (1.Arctic Research Center, Hokkaido University、2.Institute of Seismology and Volcanology, Faculty of Science, Hokkaido University、3.Atmosphere and Ocean Research Institute, University of Tokyo、4.Institute of Low Temperature Science, Hokkaido University)

キーワード：Ocean Bottom Seismometer, glacier, cryoseismology, Greenland, whales, acoustics

Recently, a lot has been learned about glacier dynamics from monitoring seismicity of glacial origin, including calving, crevassing, basal processes, and subglacial hydrology. Near glacier calving fronts, surface seismic 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 pioneered and applied ocean-bottom seismology to the calving front of a tidewater glacier in northwest Greenland. We present details of this multi-purpose experiment and describe the technical challenges, noise analysis, and examples of recorded seismo-acoustic data. This includes tide-modulated seismicity with thousands of icequakes per day and the first near-source (∼200–640 m) underwater record of a major kilometer-scale calving event in Greenland, which generated a glacial earthquake that was detectable ∼420 km away. At the same time, our approach offers a unique opportunity to monitor the acoustic presence of such poorly studied endemic Arctic animals as narwhals.