Probabilistic seismic hazard analysis using kernel density estimation technique for Chennai, India

Delineation of the seismic area source zone is an important step in seismic hazard analysis which is carried out mainly on the basis of geographical, geological and/or seismotectonic characteristics of the region. Hence it requires knowledge or involvement of the experts from these fields, and yet the zonation suffers from subjectivity. This is especially true in the case of distributed seismicity where a correlation between geological features and earthquakes does not exist. One of the alternatives to the conventional method of area zoning in such cases is the zone-free approach. One of the zone-free approaches is the kernel technique of hazard estimation wherein the seismicity of a region, defined in terms of theGutenberg-Richter (G-R) recurrence law, is replaced by a spatially smoothened activity rate probability density function. Chennai city lies in a low tomoderate seismicity region and there are nomajor faults causing earthquakes in this region. The kernelmethod is used in estimating the probabilistic seismic hazard forChennai and the results are compared with the standard Cornell-McGuire approach. It is observed that the results match well for the annual probabilities of exceedance for different values of peak ground acceleration expected at Chennai.