Postseismic deformation following the 2009 Mw7.8 Dusky Sound earthquake

Abstract

The MW7.8 Dusky Sound earthquake took place in the complex tectonic region of Fiordland on 15 July 2009, rupturing upward along the Puysegur trench. The earthquake resulted in significant coseismic and postseismic deformation in the lower half of the South Island, New Zealand. Only one GNSS station was located within 100 km of the epicentre at the time of the earthquake. Five weeks after the earthquake a network of GNSS campaign sites were remeasured to evaluate coseismic and early postseismic deformation across the region. 

Measurements of a few GNSS campaign sites were repeated in 2010 and the whole Fiordland network was remeasured in 2014. As part of this project we remeasured 18 sites in Fiordland to evaluate long term postseismic deformation in the region. In addition, nine semi continuous GNSS stations were operated by University of Otago and two new continuous GNSS stations were installed in collaboration with GeoNet in 2020 in key location, Secretary Island and Resolution Island. The data show continued but slowly decaying postseismic deformation in the region. Future work will focus on exploring models of postseismic processes in the region and to evaluate stress transfer on active faults in the South Island.

References

Reactivated afterslip induced by a large regional earthquake, Fiordland, New Zealand(external link)

Hamling, I. J., and S. Hreinsdóttir (2016)

Geophys. Res. Lett., 43, 2526–2533, doi:10.1002/2016GL067866.