New Zealand Journal of Geology and Geophysics abstracts
Recent vertical offset and near-surface structure of the Alpine Fault in
Westland, New Zealand, from ground penetrating radar profiling
MARK D. YETTON
DAVID C. NOBES*
Natural Hazards Research Centre
Department of Geological Sciences
University of Canterbury
Private Bag 4800
Christchurch, New Zealand
Abstract The Alpine Fault in central Westland is an oblique
slip fault with a predominantly strike-slip component of 25-35 mm/yr. The
smaller vertical component has been variously estimated at between 5.5 and
14 mm/yr. Ground penetrating radar and level profiles of the Alpine Fault
beside the Toaroha River in Westland indicate that there has been vertical
movement of 21.75 +/- 0.5 m of a fluvial surface dated at between 2420 and
3150 yr. This yields an average vertical movement of 7.8 +/- 1 mm/yr,
and is consistent with an estimate derived from regional studies at Paringa,
which excludes the local effects of tilting. It is a little higher than uplift
rates of 5.5 mm/yr previously estimated by Bull and Cooper, based on the
current elevation of inferred uplifted Pleistocene marine terraces from the
same general area, but is of the same order as their estimate.
Keywords Alpine Fault; ground penetrating radar; vertical
offset; near-surface structure
New Zealand Journal of Geology & Geophysics, 1998, Vol. 41:
485-492
0028-8306/98/4104-0485 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (967K); (scanned from paper original: notes about this process)
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