Abstract
The contribution of remote sensing and geographical information system (GIS) techniques to estimate the surface level seismic hazard was investigated using topographic gradient maps in the states of Tripura and Mizoram. This paper addresses a vital issue on the estimation of the seismic hazards of Northeast (NE) India, where the hazards are high and the risk is also high. In developing site response maps or seismic hazard (surface acceleration) maps, it is difficult to obtain near-surface soil data (site-specific data) through geophysical/geotechnical field investigations at a smaller resolution scale (a state/region or country level). The topographic slope provides a reliable proxy because the rocky materials maintain a steep gradient/slope compared to soft soil deposits. In this paper, peak ground acceleration (PGA) at the bedrock for the states of Tripura and Mizoram in NE India has been estimated using probabilistic seismic hazard analysis (PSHA), which considers linear sources and events (from 1731 to 2010) with appropriate ground motion prediction equations applicable for NE India. Further, the authors have adopted the square root impedance model to estimate the spectral amplification of the study area to bring the hazard from bedrock level to surface. Authors have classified the entire study area as site classes B, C, and D categories and thereafter estimated spectral amplifications for the site periods (0.40, 0.21, 0.11, and 0.01s). The surface level PGA (g) and amplification maps have been developed using a probabilistic approach considering PGA at the bedrock level. The results indicate that this area is highly sensitive to spectral responses, such as spectral acceleration or spectral amplification rather than PGA. (C) 2016 American Society of Civil Engineers.
Published Version
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