Understanding earthquake disaster in central Himalayas - a perspective of mitigation and hazard prediction

Abstract

Annually, about 100,000 earthquakes of magnitude more than three hit the earth. As a result, more than 15 million human lives have been lost and damage worth of hundreds of billions of dollars has been inflicted in the recorded history due to these disasters. More than a dozen earthquakes of M_s > 7.5 have occurred in the Himalayan region since 1897.The seismic activity in the Himalayan frontal arc is the result of continued collision between the Indian and Eurasian plates.

Most of the earthquake generation models currently used for seismic hazard evaluation are based on the assumption of Poisson or other memoryless distribution, i.e. low-magnitude earthquakes follow the Poisson distribution (random event) and large-magnitude events follow the exponential distribution (non-random). The study suggests that the region has low probabilities and large mean return periods for higher-magnitude earthquakes. The earthquake generation process in Nepal Central Himalayas supports the time- and magnitude-predictable model, which is valid for 5.5< M_s <8.6. The analysis suggests that the probability of occurrence of moderate earthquakes (M_s = 5.8-6.5) in the next decade in the Central Himalayan region is very high (0.59-0.91), whereas it is very low (<0.40) for southern Tibet.