Seismo-Acoustic Detection and Localization of Iceberg Collapse in Atka Bay, Antarctica

On 12 January 2022, an iceberg collapsed at the edge of frozen Atka Bay, Antarctica. The event generated seismic, hydroacoustic, and atmospheric infrasound waves recorded by a local network comprising land- and iceshelf-based seismometers, an underwater hydrophone, and an on-ice infrasound array. Analysis of the seismic and hydroacoustic data shows that the collapse occurred in at least three stages separated by approximately 16.5 and 8 s. The first stage produced a seismic head wave, a P-wave, and a Rayleigh wave, and clear hydroacoustic and infrasound arrivals. Later stages were dominated by hydroacoustic and seismic Rayleigh waves. Two localization techniques were benchmarked: azimuthal cross-bearing and a Bayesian joint inversion based on time-difference-of-arrival. Both approaches accurately located the iceberg within a few hundred meters of its geolocation. These unique observations highlight the value of continuous seismo-acoustic monitoring for investigating local cryospheric dynamics.