New Zealand Journal of Geology and Geophysics abstracts
Plate coupling and the hazard of large subduction thrust earthquakes at the
Hikurangi subduction zone, New Zealand
MARTIN REYNERS
Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand
Abstract Recent dense deployments of portable seismographs
along the Hikurangi subduction zone have provided insights into the structure
and seismic strain regime of the subducted and overlying plates, and the nature
of plate coupling at the shallow part of the plate interface. Beneath
Marlborough, the plates appear to be permanently locked, and large subduction
thrust events are not expected. In the Wellington and Wairarapa regions, the
plates appear to be strongly coupled over a downdip width of the plate
interface of c. 70 km. Subduction thrust earthquakes of about
MW 8.0 are estimated for this region. Farther to the northeast, the
downdip width of the inferred locked portion of the plate interface
progressively decreases, and subduction thrust events of about MW 6.9
are estimated for the northern part of the Raukumara Peninsula. In the south of
the subduction zone, changes in coupling arise principally from changes in the
thickness of the subducted plate, whereas in the north they are mainly due to
changes in thickness of the overlying plate. Tectonic rotations within the
overlying plate observed paleomagnetically appear to be a natural consequence
of changes in plate coupling along the subduction zone.
Keywords Hikurangi subduction zone; subduction thrust
earthquakes; plate coupling; seismic hazard
New Zealand Journal of Geology & Geophysics, 1998, Vol. 41:
343-354
0028-8306/98/4104-0343 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (2518K); (scanned from paper original: notes about this process)
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