G.A. Khattak | USGS Science

USGS2010

Evolution of earthquake-triggered landslides in the Kashmir Himalaya, northern Pakistan

The influence of the 08 October 2005 Kashmir earthquake and subsequent snow melt and monsoon rainfall on slope stability was evaluated using repeat photography in the Kashmir Himalaya of northern Pakistan. Sixty-eight landslide-affected locations were selected and photographed in November 2005, May/June 2006, June 2007, and August 2007 to evaluate all potential geomorphic changes. Eighty percent of the locations showed no or very little change, 11% of the locations showed a partial vegetation recovery on the slopes, while 9% showed an increase in the landslide area. All those locations that showed an increase in landsliding were located along rivers and/or roads. The small change in landslide extent is remarkable given that the region experienced one of the heaviest monsoon seasons in the last decade and is counter to earlier predictions of accelerated slope erosion by landsliding in the immediate years following the earthquake. Extensive fissures and ground cracks at many localities, however, still present a potential of future landsliding under wetter conditions. ?? 2009 Elsevier B.V. All rights reserved.

Geomorphology↗

USGS2008

Landslides triggered by the 8 October 2005 Kashmir earthquake

The 8 October 2005 Kashmir earthquake triggered several thousand landslides. These were mainly rock falls and debris falls, although translational rock and debris slides also occurred. In addition, a sturzstrom (debris avalanche) comprising ??? 80??million m3 buried four villages and blocked streams to create two lakes. Although landsliding occurred throughout the region, covering an area of > 7500??km2, the failures were highly concentrated, associated with six geomorphic-geologic-anthropogenic settings, including natural failures in (1) highly fractured carbonate rocks comprising the lowest beds in the hanging wall of the likely earthquake fault; (2) Tertiary siliciclastic rocks along antecedent drainages that traverse the Hazara-Kashmir Syntaxis; (3) steep (> 50??) slopes comprising Precambrian and Lower Paleozoic rocks; (4) very steep (?? 50??) lower slopes of fluvially undercut Quaternary valley fills; and (5) ridges and spur crests. The sixth setting was associated with road construction. Extensive fissuring in many of the valley slopes together with the freshly mobilized landslide debris constitutes a potential hazard in the coming snowmelt and monsoon seasons. This study supports the view that earthquake-triggered landslides are highly concentrated in specific zones associated with the lithology, structure, geomorphology, topography, and human presence. ?? 2007 Elsevier B.V. All rights reserved.

Geomorphology↗