Attenuation Relationship for Peak Horizontal Acceleration of Strong Ground Motion of Uttarakhand Region of Central Himalayas

Abstract

ABSTRACT An attenuation relationship has been developed for Uttarakhand, a state of Republic of India (part of central Himalayas) by using the records of earthquakes occurred in the region in the past by strong ground motion networks of U.P. array, project “National strong motion Instrumentation network” and network of project “Earthquake early warning system for Northern India”. Uttarakhand region lies in the central seismic gap where scientists have estimated that a large-sized earthquake is overdue. Largest peak ground acceleration of two horizontal components of total 116 records of 9 earthquakes (5.0≤ Mw≤6.8) are used in the development of the new relationship. Two-step stratified regression model is chosen. The proposed attenuation relationship is: where A is peak horizontal acceleration in g of strong ground motion, M is magnitude and X is hypocentral distance from the source. The standard error () of the proposed relationship is 0.281. The developed attenuation relationship will be useful for site specific studies, seismic hazard estimation and other engineering applications. The attenuation relationship can be further upgraded with the availability of earthquake records in future.