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Microseismicity Catalog of Icequakes Induced by Ocean Swell at the Ross Ice Shelf Ice-Front

Ice shelves are a critical physical impediment to the flow of grounded ice toward the ocean, thereby mitigating subsequent impacts to sea level. Ocean wave interactions with ice shelves generate a continuous background wave field of high frequency Lamb, and other plate-guided waves that can trigger micro-icequakes (magnitude ~ -2.5), and calving. Three broadband seismographs deployed approximately 2 km from the ice front of the Ross Ice Shelf in west Antarctica between 2014-2017 (e.g., Bromirski et al., 2015) established that 8-30 s period ocean swell generates impulsive high-frequency seismicity. In some cases, these seismic impulses are associated with the multistage failure of near-front crevasses that culminate in calving (Aster et al., 2021). Ice shelf rifting, fracture, and flexure have also been interpreted from seismic events detected across the expanse of the ice shelf from the full array of 34 seismographs in this deployment (e.g., Baker et al., 2021). We are establishing a catalog of swell-induced short-period seismic events spanning the complete dataset at the three ice-front stations by analyzing swell (0.03–0.12 Hz) and high-frequency (0.5–5 Hz) band-pass filtered seismograms. Subevents from the dataset will be extracted through the stacking of transient event peak detections to produce matched filter templates. The templates will be processed with an efficient cross-correlation analysis (Senobari et al., 2019) to complete the catalog and characterize the subevent categories. The catalog will be leveraged to examine oceanic controlling mechanisms of cryo-seismic phenomena. Ocean parameters will include wave height and direction, swell (storm) origin, wave period, and sea ice state. Icefront icequakes are most frequent during the austral summer in the absence of sea ice which attenuates ocean swell (Chen et al., 2019). Antarctic sea ice minimum extent reached the lowest minimum in the 44-year record in February of 2023 (Purich & Doddridge, 2023), and seismic observations from this dataset will inform and benchmark the ice-ocean processes that influence stability at the ice shelf edge.

Session: Applications and Discoveries in Cryoseismology Across Spatial and Temporal Scales [Poster Session]

Type: Poster

Room: Exhibit Hall

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Elisa McGhee

Student Presenter: Yes

Additional Authors