Site Effects Estimation in Delhi from the Indian Strong Motion Instrumentation Network

Abstract

The recent spurt in global earthquake activity has enhanced the consciousness about the increasing vulnerability of large population in the region close to Himalayas and has made significant long‐term social and economic impacts. The observation of strong motion and the investigation of the destruction from these earthquakes provide the disciplines of seismology and earthquake engineering with informative and valuable data, experiences, and lessons and raise a number of important scientific challenges. Himalaya is among the most seismically active regions in the world and has experienced several earthquake disasters during historical times. In the last 50 years, the population of India has doubled and resulted in the very rapid growth of settlements, especially in urban areas. At present, about 50 million people in India, living in the Himalayan region and the adjoining plains, are at risk from earthquakes. During the last 200 years, the Indian peninsula has experienced several great earthquakes with a magnitude above 8.0, namely, the Kutch, Gujarat earthquake (1819); the Assam earthquake (1897); the Kangra earthquake (1905); the Bihar–Nepal earthquake (1934); and the Assam earthquake (1950). Most of the parts of the Himalayas comprising North India and Northeastern India are mapped as either seismic zone IV or V in the seismic zonation map of India (on a scale of II–IV). Two of the recent significant earthquakes in North India are the Uttarkashi earthquake of 1991 ( M w 6.8) and the Chamoli earthquake of 1999 ( M w 6.5). Despite being one of the most seismically active regions of the world, the strong‐motion data set in India is, in general, very sparse. For this reason, the seismic hazard in India, until now, has been estimated using either the intensity data or attenuation relations derived for other regions (e.g., Khattri et al. , 1984; Krishna, 1992). Therefore, in the absence of adequate …