Spectral Amplification Factors of Indian Earthquake Ground Motion

The spatial verification of ground motion in Kolkata which is as metropolitan district (KMD) has been estimated by generating synthetic ground motion considering the point source model coupled with site response analysis. The most important source was picked out from regional seismotectonic map which covers the area around 350km radius all over the Kolkata. When the soil investigation of 121 boreholes the report of soil data bank project were collected. As maximum amplification in some areas of KMD was found to around 3.0 times as compare to rock level. Damages of buildings are the effects of earthquake in which the motion of surface ground motion at the site. Presently work highlights are the importance of bedrock motion upon the response of a soil column. When a typical borehole was analyzed for a wide range was up to 30m depth and was recorded bedrock motion in the absence of region ground motion records. Answer it has been recorded that the bedrock motion with low amplitude produces high amplification factor while high amplitude produces low amplification factor. In seismic microzonation practices of urban centers, the amplitude of bedrock motion and the amplification factor are considered independently for assigning rank and hazard index. A combine approach is required while assigning the rank in estimating the hazard index value .such outcome will affect the current seismic microzonation practices as well.