Detecting and Locating Icequakes on Erebus Volcano

Mt Erebus, the world's southernmost active volcano, lies on Ross Island, Antarctica, roughly 36 km north of McMurdo Station. It is best known for its rare, persistently convecting phonolite lava lake that exhibits low-level, quasi-repeating strombolian-style eruptions associated with degassing. The edifice is also covered by a glacial system composed of mostly permanent snow and ice that exhibits frequent icequake seismicity due to fracturing at very shallow depths. These glacial microseismic sources provide a unique opportunity for studying the subsurface of volcanic structures due to their wide spatial distribution and their impulsive signatures. Previous Erebus seismic studies have successfully produced tomographic scattering maps of the shallow volcanic subsurface utilizing strombolian and icequake coda correlations. This study intends to derive icequake source locations by assembling a surface wave eikonal tomographic map combined with an oct-sampler location algorithm to effectively build a flexible local detection/location framework specifically for volcanoes. The study's data consists of continuous seismic records from the Erebus Tomography and Source Studies (ZW.ETB) and Mt. Erebus Volcano Observatory (Y4.ETS) networks deployed from 2007 to 2009. To assemble a comprehensive record of icequakes, we apply a Short-Time/ Long-Time Averaging detection algorithm that distinguishes instantaneous event amplitudes from the average seismic noise amplitude. Furthermore, we propose to assemble a surface wave tomographic map by applying the eikonal equation to calculated traveltime surfaces derived from reconstructed Rayleigh wave empirical Green's functions. Finally, we intend to utilize our tomographic velocity model, station coordinates, and phase arrival times to estimate icequake source locations as input arguments in a nonlinear algorithm.