Upper plate heterogeneity along the Southern Hikurangi Margin, New Zealand

Geophysical Research Letters
By: , and 

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Abstract

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.

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Publication type Article
Publication Subtype Journal Article
Title Upper plate heterogeneity along the Southern Hikurangi Margin, New Zealand
Series title Geophysical Research Letters
DOI 10.1029/2019GL085511
Volume 47
Issue 4
Year Published 2020
Language English
Publisher American Geophysical Union
Contributing office(s) Volcano Science Center
Description e2019GL085511, 9 p.
Country New Zealand
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