Scenario Seismic Risk assessment of 1934 Bihar-Nepal Earthquake

This paper presents seismic risk assessment of Bihar considering a hypothetical earthquake event similar to 1934 Bihar-Nepal earthquake. Assessment of risk has been carried out for all districts of Bihar and risk is presented in terms of economic loss. The loss estimation is performed through the combination of seismic hazard, structural vulnerability, and exposure data. Regarding the seismic input, a non-linear probabilistic approach is used to estimate the hypocenters of 1934 Bihar-Nepal earthquake and other source parameters are taken from literature. Abrahamson and Silva (2014) ground motion prediction equation is used to generate the strong ground motion at the surface level. Building exposure data are based on national census survey of India 2011. The census data provides common building typologies for each district and their relative distribution. On the basis of wall material used for construction all the buildings are grouped into four class, and seismic vulnerability functions (Martin and Silva,2011) are assigned to each building class. For each districts, total number of buildings are aggregated at the location of the maximum ground motion.  The area per building class has been assumed and reconstruction costs per square metre for each districts have been assigned based on local expert input and values identified in the literature. Finally, the district level distribution of economic loss for this earthquake scenario is obtained using the OpenQuake-engine. From this study, the expected economic loss is highest in Madhubani district followed by Muzzafarpur, Dharbanga and Sitamarhi district. Un-reinforced masonry buildings type construction, most prevalent in the rural region would experience maximum loss. A repeat of 1934 Bihar-Nepal earthquake in present day would have devastating consequences, although this scenario addresses a hypothetical event, the seismic risk assessment constitute important tools for framing public policies toward land-use planning, building regulations, insurance, emergency preparedness and could eventually minimizes economic disruption caused by earthquake.