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SAHKE seismic‐scatter imaging of subduction beneath Wellington, North Island, New Zealand
Author(s) -
Kurashimo Eiji,
Henrys Stuart,
Sato Hiroshi,
Iwasaki Takaya,
Okaya David,
Sutherland Rupert,
Stern Tim,
Iidaka Takashi,
Ishiyama Tatsuya,
Savage Martha
Publication year - 2015
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 - 10.1002/2015gl063230
Subject(s) - subduction , geology , seismology , episodic tremor and slip , slab , slip (aerodynamics) , induced seismicity , geophysics , tectonics , physics , thermodynamics
Scattering reflectivity analysis of onshore seismic data (Seismic Array HiKurangi Experiment) images slab geometry and crustal structure at a geodetically locked subduction boundary. A broad seismic scattering zone (BSZ) up to 10 km thick above the subduction interface at depths of 16–30 km has seismic properties ( V p , V p / V s , and Q ) that imply high fluid pressures, probably associated with underplated sediments. The listric strike‐slip Wairarapa Fault and other splay faults that sole into the BSZ imply long‐term weakness. High rates of intraslab seismicity with low rates above the slab imply stress decoupling across the BSZ. Association of high fluid pressures and long‐term weakness with geodetic locking is in contrast to similar observations at zones of slow slip at the northern Hikurangi margin and suggest that either (1) pore fluid pressure or locking behavior may cycle over times longer than two decades or (2) local material properties play a significant role in determining if slow slip or locking occurs.