Abstract

An attenuation relationship for peak horizontal ground accelerations for Himalayan region in India has been developed. The data base consists of 66 peak ground horizontal accelerations from five earthquakes recorded by strong-motion arrays in India. The present analysis uses a two-step stratified regression model. The attenuation relationship proposed is
log (A) = -1.072 + 0.3903M - 1.21 log (X + e^0.5873M), where A is the peak ground acceleration (g), M is the magnitude, and X is the hypocentral distance from the source. The residual sum of squares is 0.14. Comparison with other such attenuation relationships have been made. The proposed relationship giving lesser values at shorter distances compared to other relationships needs further investigation with a larger data set. The attenuation relationship needs upgradation when more data become available in future.

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