ATTENUATION RELATIONSHIP FOR ESTIMATION OF PEAK GROUND HORIZONTAL ACCELERATION USING DATA FROM STRONG-MOTION ARRAYS IN INDIA

An attenuation relationship for peak horizontal ground accelerations f or Himalayan region in India has been developed. The data base consist s of 66 peak ground horizontal accelerations from five earthquakes rec orded by strong-motion arrays in India. The present analysis uses a tw o-step stratified regression model. The attenuation relationship propo sed 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 m ade. The proposed relationship giving lesser values at shorter distanc es compared to other relationships needs further investigation with a larger data set. The attenuation relationship needs upgradation when m ore data become available in future.