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Abstract. Lombok Island is located in the Nusatenggara region, which is considered as one of the most active seismic parts of Indonesia. The determination of seismicity is crucial to the island, since Lombok Island is a relatively dense populated small island. Earthquakes that occurred around the island were generated by southern subduction mega-thrust and northern back-arc thrust. Mostly, distributions are concentrated on the north-west and south-east parts of Lombok Island. Probabilistic data analysis of 309 earthquake events during the period of 1973 -2017 results in the Gutenberg-Richter parameters (a and b) of 3.62 and-0.53 indicating medium to high seismic activities. The Joyner-Boore attenuation relation seems to be suitable for seismic characteristics of the island. The reconstruction of tectonic setting indicates that the Benioff zone may develop at the depths of 150 km beneath the island causing horizontal tectonic forces working within the direction of N 171 0 E -N 351 0 E. This could create a strike-slip fault on the crustal basement within the NE -SW direction.

The past earthquake records in North Lombok show the high level of earthquake hazard in this area. The maximum magnitude of the earthquake was 6.4 Mw on May 30th, 1979. But, there were no tsunami events records due to those earthquakes. Nevertheless, this area is very close to Mataram City (province capital city) and tourism area. Therefore, the assessment of tsunami hazard is very important. The tsunami simulation was conducted by using COMCOT Model, which is based on the North Lombok Earthquake as the initial condition. The simulation result shows the prediction of tsunami travel time is about 18 ~ 20 minutes from the source location to Mataram City. The height of the tsunami wave is 0.13 ~ 0.20 meters due to the earthquake magnitude is about 6 Mw.

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