Research Press Release

Caterpillar-like motion of the Kohat Plateau

Nature Geoscience

January 16, 2012

On 20 May 1992, an unusual earthquake of magnitude 6.0 occurred on an almost horizontal fault plane beneath the Kohat Plateau, Pakistan, reports a study published online this week in Nature Geoscience. This implies that future earthquakes could potentially occur beneath the Plateau ― an area that wasn’t highlighted as presenting a risk previously. Roger Bilham and colleagues use seismic and satellite data to assess the deformation caused during this earthquake. Ordinarily the plateau creeps southwards without causing any large earthquakes. It is presumed that this gradual motion is accommodated by the presence of a viscous layer on the fault slip plane that acts as a lubricant. However, a rupture of this almost horizontal fault plane during the earthquake implies that there the plateau is locally grounded to the underlying rocks and that friction can build up on these patches. The results suggest that the plateau moves forward with a caterpillar-like motion, and with ongoing aseismic creep, more seismic ruptures could occur.

DOI:10.1038/ngeo1373 | Original article

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