'Nepal disaster highlights need for multi-hazard assessment of Himalayas'

The Himalayas face the threat of a cascading disaster, where a single high-altitude calamity can trigger avalanches, block rivers and unleash flash floods, rapidly magnifying destruction downstream -- a danger laid bare by Nepal's recent catastrophe, said a senior Geological Survey of India official.

Therefore, Himalayan hazards cannot be assessed in isolation, he pointed out and stressed the need for combining satellite-based observations with field investigations and ground instrumentation.

A case in point is the Nepal disaster that appears to have involved cascading processes.

Satellite analysis identified an impoundment near the Langtang Lirung ice-rock avalanche site, with imagery of August 28 showing an approximately 11-hectare water impounded area.

This provides evidence that the initial ice-rock failure was associated with temporary obstruction and water accumulation in the river system, said Pradeep Singh, the ADG of Policy Support System at the Geological Survey of ...