Seismic investigation of the 2010-2011 volcanic unrest in Marie Byrd Land, West Antarctica

We use two years of continuous seismic data recorded by the temporary POLENET network to study the volcano-tectonic context of the Marie Byrd Land and the West-Antarctic Rift System. We present an ambient noise tomography along the POLENET transect to build an isotropic shear-wave velocity model of the area. The joint inversion of Rayleigh and Love waves further suggests the presence of positive radial anisotropy beneath the mountain ranges, indicating horizontal structures. We then use template matching to detect deep long period seismicity associated with magmatic intrusions below Marie Byrd Land (Lough et al., 2013). Two main seismic swarms emerge from our detection algorithm (January-March 2010 and March-April 2011), accompanied by smaller swarms and background seismicity throughout the two years of data. The characteristics of the second main swarm differ from the first main swarm and the other background seismicity in terms of depth and source signature. Analysis of GPS time series and Coda Wave Interferometry measurements hint toward a possible small subglacial eruption at the onset of the second swarm, or at least an increased background heat flow which potentially melted several million cubic meters of ice.