ESTIMATION OF KAPPA FOR THE GARHWAL HIMALAYA USING LOCAL EARTHQUAKES

Abstract

This study aims to estimate attenuation characteristics of the Garhwal Himalayan region of Uttarakhand, India concerning various strong-motion parameters such as Kappa value (κ). A total of 65 earthquakes recorded at the Garhwal Himalayan region of Uttarakhand, India are used for the purpose. Present study area, Garhwal region falls in the North-West Himalayan region. The Garhwal Himalaya is one of the seismically active regions of the world. Most parts of this region fall in the highest seismic hazard zone defined in the seismic zoning map of India. Present study focuses on how the seismic waves are being attenuated at high frequency. It can be explained by a decay parameter called kappa (κ). In this study, introduction about kappa factor is briefly given. Some geographical information about garhwal region is presented. The important method of Anderson and Hough (1984) to estimate kappa factor, which is being followed, is briefly explained along with the procedure. To carry out the analysis I have used SEISAN software and calculated average kappa values of the study area. The average kappa values of individual stations of Garhwal Himalayan region are ranging between 0.018 – 0.080 and this much variation occurred may be due to local site effects or geology. Likewise, the average kappa value for whole Garhwal Himalayan region was found to be 0.0466 and it is in comparison with the other regions of the world.