Seismic Event Locations Beneath Montserrat
Abstract
We investigate resolution and velocity-model dependence of volcano-seismic event locations beneath the Island of Montserrat. Our focus is on seismic events from the early stages of the eruption of Soufriere Hills Volcano which began an intermittent eruptive episode in 1995 that continues today. Our ultimate goal is to relocate events in 3D velocity models estimated from recent active and passive seismic deployments, especially SEA-CALIPSO. We have begun to locate seismic events using grid searches and least-squares inversion using travel times computed in simple and complex models using finite-difference solutions of the Eikonal equations. The small volume rich in activity with depths ranging from at least six km below se-level to one km above sea-level provides a natural laboratory for examining small seismic event location capabilities. Event locations and uncertainties are estimated using a two-step process based on arrival-time observations. Grid searches in simple media are used to explore the misfit variation with position for well observed events (larger events with more than six P-wave observations) and to examine hypocenter resolution and well established phenomena such as depth and origin time tradeoff. The influence of outliers is explored by comparing least-squares and robust arrival-time misfit metrics. After exploring and quantifying capabilities, a larger set of events will be located to help illuminate volcano-seismic processes beneath Soufriere Hills. This work was performed as part of an undergraduate thesis with partial support from Penn State's Schreyer Honors College and Department of Geosciences.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.V51C2039M
- Keywords:
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- 7280 Volcano seismology (8419);
- 8419 Volcano monitoring (7280)