Seismic Hazard in the Northern India Region

Abstract

The economic and social effects of earthquakes can be reduced through a comprehensive assessment of seismic hazard and risk that leads to increased public awareness, seismically sensitive land-use planning, and the implementation of seismically sound building-construction codes. Critical analysis and assessment of the implications of the occurrence of seismic hazard require information comprising both spatial and nonspatial factors influencing the hazard. The recent spurt in damaging earthquakes in India has made it imperative to actively seek reasons and remedies for the damage and loss of life caused by the moderate earthquakes. The recent disastrous earthquakes of Chamoli (29 March 1999), and Uttarkashi (20 October 1991) in the northern India region demonstrated that substantial damage and loss of life can occur in specific areas related to local ground conditions and faulty structural designs. In the present study seismic zonation has been carried out for the northern India region based on a newly compiled catalog for the region. This region has a long seismic history, having experienced earthquakes of local origin as well as those with Himalayan origin. A tectonic map of the region has been prepared (Figure 1) based on the features as given in GSI (2000). This region includes several dominant features, such as the Himalayan Main Boundary Thrust (MBT), Main Central Thrust (MCT), Main Frontal Thrust (MFT), North Almora Thrust (NAT), and South Mmora Thrust (SAT). Regional features include the Sohna Fault, Mathura Fault, Mahendragarh Dehradun Fault, Rajasthan Great Boundary Fault, and Moradabad Fault, in addition to several minor lineaments. The results obtained in the present study are considered the first step toward microzonation. These results may be directly used for further work to predict expected strong ground motion, including the effect of site conditions. Both the results presented in this study and the newly compiled earthquake catalog are …