New Zealand Journal of Geology and Geophysics abstracts
Morphology and slip rate of the Hurunui section of the Hope Fault,
South Island, New Zealand
R. M. Langridge
K. R. Berryman
Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand
email: r.langridge@gns.cri.nz
Abstract The Hurunui section of the Hope
Fault is a
newly defined, 42 km long geomorphic fault section which extends from
Harper Pass to the Hope-Boyle River confluence. Reconnaissance mapping
along the Hurunui section from Hope Shelter to Harper Pass provided new
data on its location, geomorphology, displacement, and slip rate. More
than 200 previously published field observations of dextrally and
vertically displaced landforms along the fault provide data on the
distribution of displacement along the fault trace. Five radiocarbon
dates found in association with offset geomorphic features are
presented and two new measures of dextral slip rate are calculated. At
McKenzie Stream, a late Holocene fan complex is cut by the Hope Fault.
Young abandoned and active channels on this surface show dextral
offsets of up to 22 ± 2 m along a south-facing scarp with a
height of up to 5 m. Woody litter from a unit in this complex has
yielded a radiocarbon age of 2331 ± 55 yr BP and a corresponding
minimum horizontal slip rate of 8.1–11.0 mm/yr. At Macs Knob, large
dextral deflections of stream catchments are linked to episodes of
glacial resetting of the landscape. Correlation of the offset of “Macs
stream” (166 ± 17 m) with a post-Aranuian age peat (10 782
± 60 yr BP) yields a maximum horizontal slip rate of 13.0
± 1.5 mm/yr. The single-event dextral displacement, based on
offset stream channels at McKenzie fan, is 3.2–3.8 m (av. c. 3.4 m).
The ratio of dextral to vertical slip is c. 7 ± 2:1, indicating
that the Hope Fault has a dominantly strike-slip sense of motion.
The average recurrence interval for the last
5–7
events (i.e., to produce 19–24 m slip at McKenzie fan) is
310–490
yr. The age of the most recent surface-rupturing earthquake at this
site is not known, though felt effects, fault scaling, and landscape
arguments indicate it was not the AD 1888 North Canterbury earthquake.
Keywords Hope Fault; Hurunui; neotectonics;
earthquake hazard; Marlborough Fault Zone; slip rate; South Island;
postglacial; Holocene
G04017; Received 22 April 2004; accepted 29 October 2004; Online
publication date 23 March 2005
New Zealand Journal of Geology & Geophysics, 2005, Vol. 48:
43–57
0028–8306/05/4801–0043 © The Royal Society of New Zealand 2005
PDF file of entire paper: Print-quality
(8448K) | screen-quality (1256K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
