Detailed study of slow earthquakes at Kilauea Volcano, Hawaii
Abstract
We use space geodesy and high precision micro-earthquake relocations to investigate slow earthquake (SE) sequences at Kilauea volcano. ENVISAT interferograms image the bulk motion associated with the largest and most recent, January 2005 SE. A stack of these interferograms suggests that the hanging-wall of the Hilina Pali fault was displaced by ~2 cm. There is also evidence for local deformation on discrete faults in the hanging-wall block. We investigate the possibility of a shallow normal-fault mechanism, or, at least, triggered shallow normal faulting, for this event. The possibility of an atmospheric source for the signal is explored by comparing the apparent motions with atmospheric delays estimated from our daily processing of the CGPS network. In addition to the space geodesy, we perform waveform cross correlation relocation of earthquakes triggered by SEs at Kilauea volcano's mobile south flank. We relocated 891 earthquakes from the period from 2004 through 2005, as well as for periods of +/- 1 month around the dates of all identified Kilauea SEs. The triggered seismicity consistently relocates on discrete map-view clusters aligned in the direction of the SE displacements themselves. These results strongly suggest that the triggered earthquakes induced by SEs occur on preexisting fault zones that are near failure. In a vertical cross-section, our relocations result in a subhorizontal band at ~5 km depth. This solution is consistent with published seismic reflection data that identifies moderately landward-dipping fault planes at similar depths. While epicenters are well constrained, however, poor station geometry as well as near source velocity heterogeneity may bias the relocated depth of events in this region, and so other interpretations may be equally valid. Obtaining accurate solutions for Coulomb stress modeling will likely require a dedicated and focused seismic deployment.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.T41A1534F
- Keywords:
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- 1240 Satellite geodesy: results (6929;
- 7215;
- 7230;
- 7240);
- 7230 Seismicity and tectonics (1207;
- 1217;
- 1240;
- 1242);
- 8123 Dynamics: seismotectonics