Citation

Bhardwaj R, Sharma ML, Kumar A. Disaster Adv. 2013; 6(5): 54-60.

Copyright

(Copyright © 2013, Shankar Gargh)

DOI

unavailable

PMID

unavailable

Abstract

A common way to evaluate earthquake parameters for Earthquake Early Warning (EEW) system is to make use of initial portion of the seismic wave ground motion period tau(c) depicting the magnitude (M) of the strong ground motion. tau(c) is in general expressed as the average of initial portion of primary wave (P wave) and approximately represents the width of P wave within the selected window size (generally taking 3 sec after primary wave onset) and is linearly related with magnitude of the earthquake. Since the seismic waves encompass different regions with different properties, these empirical relationships vary region to region. One of the most conspicuous property namely attenuation characteristics is being explored to be included in the regression to look into its effect on the parameters being used for EEW. This study derives regression relation in three parameters tau(c), M and Q(o) (quality factor at 1 Hz) considering five different regions of India namely, Garhwal Himalaya, Kumaun Himalaya, Northeast Himalaya, Northwest Himalaya and National capital region. The Indian dataset covering magnitude ranges between 3.3 to 6.8 and an epicentral distance up to 60 km consisting of 66 strong motion records of 33 earthquakes recorded at 49 seismic stations have been considered in the analysis. The regression of tau(c) is found to be logarithmically distributed with a strong variation for different magnitude and Q(o) values.