Seismic input at the archaeological site of Kancheepuram in Southern India

A probabilistic seismic hazard assessment at Kancheepuram in Southern India was carried out with the scope of defining the seismic input for the vulnerability assessment of historical and monumental structures at the site, in terms of horizontal Uniform Hazard Spectra and a suite of spectrum-compatible natural accelerograms to perform time-history analysis. The standard Cornell-McGuire and a zone-free approach have been used for hazard computations after the compilation of a composite earthquake catalogue for Kancheepuram. Epistemic uncertainty in the seismic hazard was addressed within a logic-tree framework. Deaggregation of the seismic hazard for the peak ground acceleration shows low seismicity at Kancheepuram controlled by weak-to-moderate earthquakes with sources located at short distances from the archaeological site. Suites of natural accelerograms recorded on rock have been selected by imposing a custom-defined compatibility criterion with the probabilistic spectra. The site of Kancheepuram is characterized by a seismicity controlled by weak-to-moderate earthquakes with sources at short distances from the site, the PGA expected for 475- and 2,475-year return period are, respectively, 0.075 and 0.132 g. The Indian code-defined spectra (DBE and MCE) tend to underestimate spectral ordinates at low periods. On the other hand, the PGA are comparable and the spectral ordinates for longer periods from the probabilistic study are significantly lower.