Passive Seismology: Lightweight and Rapid Detection of Arctic Subsea and Sub‐Aquatic Permafrost

Author:

Angelopoulos Michael1ORCID,Ryberg Trond2ORCID,Rasmussen Christian Frigaard1,Haberland Christian2ORCID,Juhls Bennet1ORCID,Dallimore Scott3ORCID,Boike Julia14ORCID,Overduin Pier Paul1ORCID

Affiliation:

1. Permafrost Research Section Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research Potsdam Germany

2. Section Geophysical Imaging GFZ German Research Centre for Geosciences Potsdam Germany

3. Geological Survey of Canada Natural Resources Canada Sidney BC Canada

4. Geography Department Humboldt‐Universität zu Berlin Berlin Germany

Abstract

AbstractLow sea levels during the last Ice Age exposed millions of square kilometers of Arctic shelves which have been subsequently submerged, creating subsea permafrost. In onshore settings, permafrost can also exist beneath water bodies such as coastal lagoons, rivers, and thermokarst lakes. We explored passive seismology as a method for mapping unfrozen sediment thickness above subsea and sub‐aquatic permafrost. We present passive seismic data collected with the Mobile Ocean Bottom Seismic Instrument (MOBSI) from the Beaufort Sea near Tuktoyaktuk in Canada, Ivashkina Lagoon on the Bykovsky Peninsula, as well as a lake and river in the Lena Delta, Siberia, Russia. We use borehole data and frost probe measurements to identify permafrost‐related H/V measurement peaks and calibrate shear wave velocities for frequency‐to‐depth conversion. We employ the shortest path and maximum signal amplitude to connect peaks and generate geological profiles. The MOBSI detected the ice‐bonded permafrost table beneath the Beaufort Sea, as well as beneath a Siberian lake and lagoon. At Tuktoyaktuk, an ocean bottom seismometer revealed a 5% scatter about the peak frequency for three‐minute time windows and over 8 hr of recording time. With peak frequencies ranging from 4.9 ± 0.2 Hz to 27.6 ± 1.4 Hz, the depth to subsea permafrost ranged from 1.4 ± 0.1 m bsl at the shoreline to 14.0 ± 0.4 m bsl 240 m offshore. Given an accurate shear wave velocity, our findings highlight that MOBSI deployment times as short as 3 min are adequate for detecting Arctic subsea and sub‐aquatic permafrost.

Funder

European Space Agency

Publisher

American Geophysical Union (AGU)

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