EAPSI: Interactions between slow slip and seismicity along the Hikurangi Margin, New Zealand

Todd Erin K, Santa Cruz CA

Investigators

Abstract

New Zealand is located on a complex boundary between the Australian and Pacific tectonic plates where the Pacific Plate sinks beneath the North Island through a process called subduction. Since subduction zones generate the world's largest earthquakes (magnitude > 9), it is important to understand the physics related to sliding processes on the plate interface and deformation in surrounding regions. In the South Island, the plate boundary continues as the Alpine Fault, a strike-slip fault where the Pacific and Australian plates slide past one another. Further south, subduction resumes in the opposite direction with the Australian Plate subducting beneath the Pacific Plate at the Puysegur Trench. This project will investigate the relationship between slow slip, motion on the plate boundary that does not radiate seismic energy, and earthquakes on the plate interface and surrounding faults. This research will be conducted at the Geologic and Nuclear Sciences Research Institute in collaboration with Dr. Charles Williams, one of the developers of a crustal deformation modeling code that will be used for the project. It has been accepted that a spectrum of strain release modes exists in subduction zones, where the Earth's largest earthquakes occur. The goal of this research is to quantify key aspects of the physics related to slow slip along the Hikurangi Margin and to elucidate the relationships between slow slip, tremor, and earthquakes. This research will make use of PyLith, a finite-element crustal deformation modeling code, to simulate slow slip along the Hikurangi Margin, New Zealand. The resulting stress changes will be analyzed along the megathrust in both the along-dip and along-strike directions as well as on surrounding faults. The spatiotemporal relationships that exist between slow slip, tremor, and conventional fast earthquakes will also be investigated. This NSF EAPSI award is funded in collaboration with the Royal Society of New Zealand.