Article ID Journal Published Year Pages File Type
6432538 Geomorphology 2014 14 Pages PDF
Abstract

•We documented coseismic ground cracks following the Darfield (Canterbury) earthquake.•Mapping and subsurface data indicate toppling and bedding-controlled translation.•Ground crack displacement and depth may be controlled by topography.•Paleoseismic studies of landslides must account for source and site characteristics.

The head scarp of the Harper Hills landslide consists of ground cracks with vertical displacement and extension that opened during the 2010 Darfield (Canterbury) Mw 7.1 earthquake. The geomorphology of the cracks, regional geology and ground penetrating radar indicate that the landslide formed by bedding-controlled translation and joint-controlled toppling, and suggest incipient deep-seated movement. Crack depth and displacement along the head scarp vary along the ridge; maximum values are located where the head scarp is closest to the local ridge line. Increased seismic shaking due to topographic and geometric amplification of seismic waves is suggested as an explanation for this relationship. An excavation across the head scarp revealed no evidence of prior slip events over a time period that is likely to exceed the return period (1000-2500 years) of peak ground accelerations experienced at this location in the Darfield earthquake. We suggest that specific seismologic attributes of the Darfield earthquake may have influenced the location of landsliding in this instance. Studies of paleo-landslides must consider crack preservation potential as well as complex source/site effects that may complicate estimates of acceleration return periods from the subsurface investigation of individual landslide head scarps.

Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Earth-Surface Processes
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