A Simplified Technique for Simulating Wide-band Strong Ground Motion for Two Recent Himalayan Earthquakes

Abstract

A simplified technique for simulation of wide-band strong motion based on simple regression relations and Empirical Green's Function (EGF) technique by IRIKURA (1986) is presented in this paper. The method uses the acceleration envelope as a shaping window for a filtered white Gaussian noise, to get the synthetic accelerogram from each subfault. Correction factors for slip of large and small events and transmission factors at each boundary of different layers are included in this synthetic accelerogram. The synthetic accelerogram obtained from each subfault is used as the Green's function to get resultant records. Simulations are made for the confirmed models of the Uttarkashi and the Chamoli earthquakes at a number of stations to get wide-band strong ground motion. The comparison of synthetic with the observed records over a wide range of frequencies for two different Himalayan earthquakes establishes the efficacy of the present technique.

Stochastic ground-motion simulation of two Himalayan earthquakes: seismic hazard assessment perspective

“…The most sought after information for generating synthetic ground-motion data consists of region-specific input parameters such as stress drop, quality factor, geometrical spreading, and site geology. Recently, a few researchers have investigated these parameters for the Garhwal region (Joshi 2004(Joshi , 2006Kumar et al 2005;Singh et al 2004;Yu et al 1995).…”

Expected peak ground acceleration in Uttarakhand Himalaya, India region from a deterministic hazard model

“…The models obtained using this relationship has been tested by Joshi (2004) for its application for the Himalayan region. In this study, the rupture plane along the identified lineament is considered as rectangular in shape (Fig.…”

“…Before using these regression relations, their applicability needs to be checked. This was done in the previous study by Joshi (2004) for Uttarkashi and Chamoli earthquakes. The minimum root mean square error (RMSE) was found in the case of the ground motion model by Abrahamson and Litehiser (1989).…”

“…Zeng et al (1994); Yu (1994Yu ( , 1995 function approach. The suitability of this technique in Himalaya has been verified by simulating and comparing the records of many past events recorded on strong motion network by Joshi (2001Joshi ( , 2004.…”

“…There are several techniques to forecast peak ground acceleration for future earthquakes in the study area. Peak ground acceleration can be estimated from simulated accelerograms using various techniques including composite source modeling technique (Zeng et al 1994;Yu 1994;Yu et al 1995;Saikia andHermann 1985 andSaikia 1993), stochastic simulation technique (Boore 1983;Atkinson 1987 andLai 1982), empirical Greens function technique (Hartzell 1978;Kanamori 1979;Hadley and Helmberger 1980;Mikumo et al 1981;Irikura and Muramatu 1982, Irikura 1983, 1986Kamae and Irikura 1998;Munguia andBrune 1984 andHutchings 1985), and semiempirical technique (Midorikawa 1993;Joshi and Patel 1997;Joshi 1997Joshi , 2001Joshi , 2004. The outline of various methods used for simulating strong ground motion is listed in Table 1.…”