Seismic Response of Sri Lanka using PSHA Technique

This paper describes a research study carried out to find the seismic response of Sri Lanka using Probabilistic Seismic Hazard Assessment (PSHA) considering seismic activities surrounding the region. Three attenuation relationships, namely Abrahamson and Silva, Raghukanth and Iyengar, and Campbell and Bozorgnia, verified to be reliable according to existing South Indian seismic data have been used in the analysis. The completeness check for the earthquake catalogue for Sri Lanka seismic scenario has been performed and 200 years of data were demonstrated to be satisfactory. PSHA technique was used with logic tree approach to minimize the effects of epidemic uncertainty. Then, Peak Ground Accelerations and Spectral Accelerations at bedrock level ignoring the overburden effects were computed for important cites in Sri Lanka and they were found to be highest in the west coastal zone within a range of 0.05 to 0.1 g and an approximate PGA value of 0.1 g in Colombo.