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Upper Plate Heterogeneity Along the Southern Hikurangi Margin, New Zealand
Author(s) -
Henrys Stuart,
EberhartPhillips Donna,
Bassett Dan,
Sutherland Rupert,
Okaya David,
Savage Martha,
Evanzia Dominic,
Stern Tim,
Sato Hiroshi,
Mochizuki Kimihiro,
Iwasaki Takaya,
Kurashimo Eiji,
Seward Anya,
Wech Aaron
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl085511
Subject(s) - geology , seismology , terrane , plate tectonics , clockwise , pacific plate , induced seismicity , slip (aerodynamics) , subduction , deformation (meteorology) , tectonics , rotation (mathematics) , oceanography , geometry , physics , mathematics , thermodynamics
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.