Seismo-acoustic detection and localization of iceberg collapse in Atka Bay, Antarctica

On January 12, 2022, shortly after 9:12 PM UTC, scientists working at the Neumayer-III scientific station in Atka Bay, western Antarctica, observed an iceberg collapse at the edge of the ice-covered bay. The iceberg had a triangular shape where each of its edges was ∼300 m long. The collapse generated seismic waves propagating through the sea ice and ice shelf and acoustic waves propagating in the ocean and atmosphere. These waves were recorded by a collection of seismic and acoustic instruments deployed on land, on the ice shelf, and underwater. In this study, we analyze the observed seismo-acoustic wavefield recorded in all three media. A combination of the seismic and underwater acoustic observations suggests at least two phases of the collapse separated by 16 s. Seismic observations show that the first arrival corresponds to a longitudinal P wave followed by a dispersed surface wave and multipath coda waves. Array processing results of the infrasound data show two overlapping arrivals, possibly a combination of direct propagation and low-altitude refraction or reflection. Finally, two localization techniques placed the iceberg within less than 300 m from its ground-truth location. These unique observations highlight the added value of continuous seismo-acoustic monitoring for studying local ice-related dynamics.