Massive earthquake swarm driven by magmatic intrusion at the Bransfield Strait, Antarctica

• Published in: Communications Earth & Environment
• Main Authors: Cesca, S., Sugan, M., Rudzinski, Ł., Vajedian, S., Niemz, P., Plank, S., Petersen, G., Deng, Z., Rivalta, E., Vuan, A., Plasencia Linares, M., Heimann, S., Dahm, T.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2022
• Subjects: King George Island; Bransfield Strait; Antarc*; Antarctica; Orca
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5010958; https://gfzpublic.gfz-potsdam.de/pubman/item/item_5010958_1/component/file_5011159/5010958.pdf

An earthquake swarm affected the Bransfield Strait, Antarctica, a unique rift basin in transition from intra-arc rifting to ocean spreading. The swarm, counting ~85,000 volcano-tectonic earthquakes since August 2020, is located close to the Orca submarine volcano, previously considered inactive. Simultaneously, geodetic data reported up to ~11 cm northwestward displacement over King George Island. We use a broad variety of geophysical data and methods to reveal the complex migration of seismicity, accompanying the intrusion of 0.26–0.56 km3 of magma. Strike-slip earthquakes mark the intrusion at depth, while shallower normal faulting the ~20 km long lateral growth of a dike. Seismicity abruptly decreased after a Mw 6.0 earthquake, suggesting the magmatic dike lost pressure with the slipping of a large fault. A seafloor eruption is likely, but not confirmed by sea surface temperature anomalies. The unrest documents episodic magmatic intrusion in the Bransfield Strait, providing unique insights into active continental rifting.