Testing Indonesia’s national seismic hazard assessment using historical intensity data

The intensities of historically damaging earthquakes (1681 – 1877) from the Wichmann catalogue of earthquakes in Indonesia are used to independently test ground motion predictions in Indonesia’s current (2010) national probabilistic seismic hazard assessment (PSHA). Using a Poisson process we stochastically generate many realisations of ground motion based on the hazard model to estimate the probability of observing the historical intensities, including uncertainties between instrumental ground motions and intensity observation. From our results we cannot statistically reject Indonesia’s current PSHA for key cities in Java; however, they do suggest that seismic hazard may be underestimated for the megacity Jakarta. Identification of plausible source models for large damaging events through scenario ground motion modelling is used to test if the seismic source model for the current PSHA captures the location and magnitude of historical earthquakes. The results demonstrate that the current PSHA underestimates maximum magnitudes on a number of presently mapped faults, including the Flores Thrust, and for intraslab events. Poster presented at the10th International Workshop on Statistical Seismology 2017