Attenuation models for expected ground motions in Sri Lanka

Infrequent seismic activities around Sri Lanka have resulted in fewer reliable attenuation models. Therefore in this paper, attenuation models have been developed using an artificially generated strong motion data set. Two sets of models were derived; one to model merely local effects within the continental crust, and the other to model regional effects including the surrounding northern Indian Oceanic crust. While the local attenuation model is more reliable in estimating ground motions up to around 400 km, the regional model shows capability inn predicting accurate ground motions at long distances as far as 1000s km. The findings are based on a validation of the models with a set of actual event records available at the country's seismic network. Finally, the results would be helpful in modelling the seismic hazard for a low seismic island region of intraplate seismicity - Sri Lanka.