New Zealand Journal of Geology and Geophysics abstracts
The AD 930 long-runout Round Top debris avalanche, Westland,
New Zealand
CRAIG A. WRIGHT
Geology Department
University of Otago
P.O. Box 56
Dunedin, New Zealand
Abstract A major landslide from the faulted range front
between the Toaroha and Hokitika Rivers, central Westland, New Zealand,
probably resulted from an earthquake on the Alpine Fault at AD 930 +/- 50 yr.
The 550 m high asymmetric scarp on Round Top, through which the Alpine
Fault trace passes, is the source of a deposit of avalanche debris with a
volume of c. 45 Mm3 spread over an area of more than
5 km2. The avalanche, which flowed more than 4 km from its
source over an alluvial plain, is an example of a life-threatening hazard which
has not previously been given adequate attention in Westland. Here, I describe
the internal fracturing and faulting of the hummocky deposit, and compare its
570 m vertical fall and 4800 m runout distance with another nearby
avalanche.
Keywords debris avalanche; Alpine Fault; earthquake; hazard;
landslide; runout; Westland; C-14
New Zealand Journal of Geology & Geophysics, 1998, Vol. 41:
493-497
0028-8306/98/4104-0493 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (999K); (scanned from paper original: notes about this process)
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