Propagation and Characteristic of Tsunami Wave in Lembeh Strait, North Sulawesi, Due to the Earthquake in the Molucca Sea

Abstract

Modeling the propagation of a tsunami triggered by an earthquake with a hypocenter in the double subduction of the Maluku Sea using the TUNAMI-N2 program has been carried out. The objectives of this research are to find out the model of tsunami propagation towards Bitung City, how the effect of Lembeh Island on tsunami waves, and the characteristics of the waves that occur in the Lembeh Strait. The modeling uses two earthquake scenarios with different magnitudes which are 7.5 Mw (scenario A) and 8.0 Mw (scenario B). The results show that the wave propagation model towards Bitung City in the two scenarios is relatively the same, but has a different arrival time and wave height depending on the earthquake energy of the tsunami generator. The arrival time of the tsunami waves in Lembeh strait area, the strait between Bitung City and Lembeh Island, was relatively slower indicating that Lembeh Island could serve as a tsunami barrier for Bitung City. The characteristics of the tsunami waves in Lembeh Strait are also different from the areas outside the strait. This is due to the effects of diffraction and wave superposition that occur in the strait area. The characteristics of the waves that occur inside and outside the Lembeh Strait are important things to know in order to determine a more optimal tsunami disaster mitigation strategy in Bitung City.