Original PTHA datasets are from GeoScience Australia. Probabilistic tsunami hazard assessments (PTHA) are analogous to probabilistic seismic hazard assessment (PSHA) which is the global standard for defining ground shaking levels for building codes and carrying out earthquake risk assessments. The PTHA method can be summarised as: 1. Determine the earthquake source zones (fault lines) to be included in the study; 2. For each earthquake fault, determine the characteristics (e.g. maximum magnitude, geometry etc.) of the earthquakes that could occur on the fault and the probability of such earthquakes; 3. Simulate all possible earthquakes for each fault and the resulting tsunami. For each coastal location calculate the tsunami waveheight that would result from the tsunami generated by each earthquake; 4. Combine these results to relate the maximum tsunami amplitude at the coast with a probability that they might occur. The characteristics of each fault were determined using the highest quality data available to the assessment team. This included historical catalogues of earthquakes and tsunami, physical laws on earthquake size, assessments made during the 2010 revision of Indonesia’s seismic hazard map, and expert scientific judgement by the assessment team. Numerical computations were performed to simulate the propagation of tsunami waves from the earthquake fault to the coast. In total, 100,000 synthetic tsunami were simulated and included in the assessment from a total of thirty earthquake faults. Twenty one faults were from around Indonesia and nine were from regional and distant sources in the Indian and Pacific Oceans. Results of the simulations were used to estimate the maximum tsunami waveheight at each coastal location around Indonesia for each earthquake. Partial pre-processing of local tsunami data is required in order to take into account the tsunami run-up and inundation process onshore. A simple procedure involving wave height and ground elevation analysis has been undertaken by the ThinkHazard! team for use within the model. More information on the GeoScience Australia process can be found at http://aifdr.org/wp-content/uploads/pdf/PTHA_Report_Final_EN.pdf Details on the pre-processing method can be found in the ThinkHazard! Methodology document.
