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Upper plate heterogeneity along the Southern Hikurangi Margin, New Zealand

January 30, 2020

Controlled and natural source seismic data are used to build a 3-D P wave model for southern North Island, New Zealand, where the Pacific Plate subducts beneath the Australian Plate at a rate of ~41 mm/year. Our analysis reveals an abrupt along-strike transition in overthrusting plate structure within Cook Strait. Contrasts in properties (Vp, Vp/Vs, and Qs) likely reflects the degree of deformation in the Australian Plate, where the Alpine-Wairau and Awatere Faults mark the northern boundary of a terrane that has undergone >50° of clockwise vertical-axis rotation since the early Miocene. Heterogeneity of the crustal transition is likely associated with changes in frictional and elastic properties that may impact elastic stress accumulation and inhibit southward propagation of megathrust earthquakes. Low connectivity of faults in Cook Strait is consistent with the heterogeneity we observe and may promote complex earthquake triggering by lateral stress loading during earthquakes or slow slip events.

Publication Year 2020
Title Upper plate heterogeneity along the Southern Hikurangi Margin, New Zealand
DOI 10.1029/2019GL085511
Authors Stuart Henrys, Donna Eberhart-Phillips, Dan Bassett, Rupert Sutherland, David Okaya, Martha Savage, Dominic Evanzia, Tim A. Stern, Hiroshi Sato, Kimihiro Mochizuki, Takaya Iwasaki, Eiji Kurashimo, Anya Seward, Aaron Wech
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70228631
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center