Ground Response Based Preliminary Microzonation of Kathmandu Valley

Abstract

This paper analyzes spatially selected 286 deep borehole logs reaching up to the bedrock and the results are presented in terms of amplification factor, ground acceleration and predominant period. The peak ground acceleration (PGA) is estimated to be 0.10 and 0.50 g indicating strong influence of nonlinearity in particular areas of Kathmandu valley wherein de-amplification is observed. The peak spectral acceleration is found to be varying from 0.30 to 1.75 g for the study area and soil predominant period is estimated in the range of 0.7 to 5 sec.  Preliminary microzonation maps for PGA and soil predominant period are prepared and presented in this paper. Comparisons and interpretations on the basis of 1934 and 2015 earthquakes are presented in terms of damage scenario.