Relocating Earthquakes of the 2009 Dusky Sound, South Island, New Zealand Sequence
Abstract
On July 15th, 2009 UTC the largest magnitude earthquake (Mw 7.8) to affect New Zealand in over 70 years occurred in Dusky Sound, a fiord located in the southwest corner of the South Island of New Zealand. In the Dusky Sound region the Australian Plate is converging obliquely with the Pacific plate at ~ 38 mm yr-1. The 2009 sequence was the southernmost in a series of seven Mw>6 earthquakes occurring over an 11 year period, including an Mw=7.2 event in 2003. The 2009 mainshock created fewer landslides and radiated relatively little high frequency energy compared with the 2003 mainshock, although both occurred on the plate interface, suggesting the 2009 mainshock had a lower stress drop. GPS studies indicate slip along the plate interface in the 2009 mainshock was highly oblique, in contrast to the region located north of the 2009 sequence where slip is partitioned into trench normal thrusting along the subduction interface and strike-slip faulting along the Alpine fault within the Pacific plate. We are relocating aftershocks of the 2009 sequence using HypoDD to better determine how this region of the South Island transitions between non-partitioned oblique subduction and a slip partitioned convergent margin. The relocations will also be used to aid in the selection of event pairs for a separate study of stress drop variations using the Empirical Greens Function technique.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.S51B2424C
- Keywords:
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- 7215 SEISMOLOGY / Earthquake source observations;
- 7240 SEISMOLOGY / Subduction zones;
- 7299 SEISMOLOGY / General or miscellaneous