Geodetic Investigation of Triggered Slip near Secretary Island, Puysegur Subduction Zone, New Zealand
Abstract
Secretary Island, at the head of Doubtful Sound in Fiordland, southwest New Zealand, has experienced three earthquakes larger than Mw 6.5 in the last 40 years: the 1989 Doubtful Sound, 1993 Secretary Island, and 2003 Fiordland earthquakes. These events were approximately coincident with the 17° bend in the strike of the young, obliquely-converging, and steeply dipping Puysegur Subduction Zone. This section of the plate interface has a history of triggered slip: the 1989 earthquake is inferred to have triggered the 1993 earthquake and, further north at George Sound, triggered afterslip was reported following the 2009 Dusky Sound earthquake. We have used Synthetic Aperture Radar (SAR) data from the ALOS1 and ALOS2 satellites to examine whether triggered slip also occurred in the vicinity of Secretary Island following the 2007 George Sound, 2009 Dusky Sound or 2016 Kaikōura earthquakes. Limitations arising from orbital drift, the frequency of SAR acquisitions and the observation geometry hinder our ability to constrain the timing, magnitude and location of reactivated slip from a source similar to the 2003 Secretary Island earthquake. Our findings indicate that slip was not triggered following either the 2007 George Sound earthquake or the 2016 Kaikōura earthquake. However, we cannot rule out triggered slip near Secretary Island following the 2009 Dusky Sound earthquake.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.G43B0752L
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 1525 Paleomagnetism applied to tectonics: regional;
- global;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 3040 Plate tectonics;
- MARINE GEOLOGY AND GEOPHYSICS;
- 7230 Seismicity and tectonics;
- SEISMOLOGY