Geodetic evidence of the volcanic magma origin of the earthquake swarm in the Scotia-Antarctica Plate Boundary

SUMMARY Large-scale geodetic monitoring of volcanic earthquakes is essential for understanding the physical mechanisms governing volcanic activity and magma migration. Recently, a significant earthquake swarm occurred around the Scotia plate. Geodetic data of 14 permanent GNSS stations on the Antarctic Peninsula, King George Island, the South Sandwich Islands and South America were collected and analysed, to monitor the crustal deformation of King George Island, the expansion of Bransfield Strait, the drift of Scotia plate and sea level anomalies. Tidal data from four permanent tide stations were analysed to monitor sea level anomalies. Results showed that after earthquakes the King George Island’s movement speed increased tenfold and its direction altered by 90 degrees. Land surface fluctuations in southeast King George Island were observed a year before the earthquakes, followed by continuous uplift. A combinatorial model including a point pressure source and expanding dike fit well with new geodetic monitoring data, revealing the impact of volcanic activity on this region. Geodetic monitoring and modelling quantitatively depicted the pre-seismic, co-seismic and post-seismic phases of geological changes, providing new evidence and insights into the complex geological structures.