Recent anomalous seismic activity in the Bransfield Strait, near King Sejong Station, Antarctic Peninsula (August 2020-February 2021)

Abstract

There have been 170 earthquakes with seismic magnitudes ranging from 4.0-6.9 in the Bransfield Strait, Antarctic Peninsula, reported by the USGS since the first event (Mw 4.9) occurred on 29 August 2020, which is anomalously high seismicity in this region. The largest event in the earthquake swarm sequence occurred ~200 km northeast of the Orca submarine volcano on 23 January 2021, which has a magnitude Mw 6.9. We investigated the seismic data recorded at JUBA where is located in the King George Island and found that total 34,101 events were detected by applying the STA/LTA method and the daily occurrence exceeds 100 events until early November 2020 then gets smaller. Furthermore, the Focal Mechanisms Classification analysis for 27 earthquakes that moment tensor solutions are provided by the USGS indicates that most events are characterized by strike-slip faultings and a few normal faulting events. Some events with a compensated linear vector dipole component of more than 10% may implicate volumetric changes associated with submarine volcanic environments, even though it should be carefully examined by collecting more data through international collaborations.