ABSTRACT

Tsunami threatens the coastal sea areas of the South China Sea. In order to figure out the impact of tsunami waves, a scenario of tsunami generated by an earthquake of magnitude Mw9.3 in the Manila trench is studied. A Boussinesq numerical model is adopted to study the impact of tsunami wave to the coastal sea areas of Vietnam and the pattern of tsunami wave during propagation. Leading wave amplitude, arrival time and flow velocity near the target locations, as well as the wave profiles, are presented.

INTRODUCTION

Two extreme earthquakes, Sumatra earthquake (at 00:58 UTC, 26th Dec. 2004) and Tohoku earthquake (05:46 UTC, 11th Mar. 2011), occurred and triggered a series of devastating tsunamis. Coasts even far away from the epicenter of earthquakes also suffered the loss of lives and properties. Since then, the potential threat of earthquake and tsunami from faults along the Manila Trench steps into the public view of littoral countries around the South China Sea, such as China, Vietnam, Philippines and Singapore et al. Offshore and near-shore structures are exposed to potential damage of waves and currents caused by a tsunami. Studies on the tsunami in the South China Sea, such as fault parameters, threats of an extreme tsunami and early warning system have been carried out in the last two decades.

The Manila Trench is an oceanic trench in the west part of the Pacific Ocean, along which the Sunda Plate (part of Eurasian Plate) is subducting under the Philippine Mobile Belt. Fault parameters, such as fault location, geometry, and length, were first published by Kirby & Geist (2006). According to the historical earthquakes that occurred in the region of Manila Trench, the scaling relation and fault parameters, Liu et al. (2009) presented a source model of the Manila faults of magnitude Mw8.0. Based on the fault parameters of the Chile tsunami (1960), the Alaska tsunami (1964) and the Indian Ocean tsunami (2004), Wu & Huang (2009) developed an earthquake source model of magnitude Mw9.35. Megawati et al. (2009) also constructed a source model of magnitude Mw9.0. The number of sub-faults in the source models proposed by Liu et al. (2009) and Wu & Huang (2009) is six, which is inherited from the work of Kirby & Geist (2006); while it is 33 in Megawati et al. (2009). Based on the models proposed by Wu & Huang (2009) and Megawati et al. (2009), Nguyen et al. (2014) developed a new worst case scenario of magnitude Mw9.3, which is adopted in this study.

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