Title: Inferring Eruption Dynamics from Seismometer-Derived Ground Tilt Measurements: A Case Study of Erebus and Augustine Volcanoes
Abstract: Broadband seismometers are sensitive to tilt as a consequence of their design. We use broadband data from Erebus Volcano on Ross Island, Antarctica, and Augustine Volcano in Lower Cook Inlet, Alaska, to estimate tilt measurements associated with individual volcanic explosions to investigate the magmatic system configuration of each volcano. At Erebus we find no evidence of tilting associated with the characteristic lava lake Strombolian explosions produced by the volcano. Tilt preceding Strombolian explosions has been observed at other volcanoes, and we interpret its lack at Erebus as evidence that its conduit system lacks sufficient viscous plugging or mechanical restrictions necessary to generate the slug transport or explosion-related forces that cause tilt. At Augustine Volcano we recover tilt changes associated with each of the thirteen events during the explosive phase of its 2006 eruption. We use the tilt changes to invert for a dual deformation source model of a depressurizing open conduit above a depressurizing prolate spheroid. This deflation source geometry is in agreement with an existing magmatic system model developed from petrologic, seismic, and GPS data, and further supports this model while highlighting the capabilities of this independent model constraint.
Biography:
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Contact: mchristo@gatech.edu
Website: https://mchristo.net
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