High-Resolution Locations of Triggered Earthquakes and Tomographic Imaging of Kilauea's South Flank
Abstract
The temporal and spatial patterns of seismicity beneath Kilauea’s south flank give insight to the structure of the decollement on which large, tsunamigenic earthquakes have occurred, and its relation to slow slip events (SSEs) which have been observed every one to two years since 1997 [Brooks et al., 2006; Segall et al., 2006; Montgomery-Brown et al., 2009]. We relocate hypocenters of volcano-tectonic earthquakes and invert for P- and S-wave velocity structure using waveform cross-correlation and a double-difference tomography technique. Our dataset includes over 4000 earthquakes and 200,000 absolute arrival times from permanent Hawaii Volcano Network (HVO) data and two higher-density temporary arrays on the south flank from November 1999 to June 2000 and from March to July 2007, the latter recording earthquakes preceding and during the June 2007 dike intrusion and SSE. The orientation of the decollement fault beneath Kilauea's south flank has been previously imaged as a northwest-dipping thrust fault at 7-9 km depth, but we find a sub-horizontal fault based on the current most well-constrained data. A swarm of over 400 well-located triggered earthquakes at 8-9 km depth occurred beneath the south flank on the southern edge of the decollement fault during the June 2007 SSE. A shallower swarm of earthquakes occurred at 2 to 6 km depth two months prior to the SSE in April 2007 immediately to the southeast of the where the subsequent June 2007 swarm took place. The April swarm may have been triggered by the Mw 8.1 Solomon Islands earthquake at ~6000 km distance, which occurred 48 hours prior to the beginning of the swarm, and may be an example of dynamic earthquake triggering. Map and cross section of stations (triangles) and selected earthquake locations (circles) showing sub-horizontal decollement and a seismicity swarm in April 2007.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.S53B..08S
- Keywords:
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- 7230 SEISMOLOGY / Seismicity and tectonics;
- 7270 SEISMOLOGY / Tomography;
- 7280 SEISMOLOGY / Volcano seismology