Site response estimation using strong motion network: A step towards microzonation of the Sikkim Himalayas

摘要

Site response in the Sikkim Himalayas is studied using digital accelerograms recorded by a seven-station-strong-motion network, established to monitor the earthquakes in the region in an effort to microzone the area. Depending on the criterion that signal-to-noise ratio must be greater than or equal to 3, out of more than fifty earthquakes recorded during it-lay-August 1999, only fifteen events are chosen for the non-reference-receiver-function-type estimate of the site amplification factors, Site response curves (with +/- 2 standard deviation uncertainty) at all the seven sites and the contour maps at central frequencies 1, 3, 5,7, 9 and 11 Hz show station to station variation of the site factors at different frequencies, reflecting the changes in geologic/geotectonic/soil conditions. The nonlinearity of the site factor is also observed due to its strong frequency dependence. Results of this investigation reveal the significance of site response studies in the microzonation for seismic hazard assessment. [References: 25]