| dc.description.abstract | On December 26, 2006, two ML=7.0 submarine earthquakes occurred offshore Ping-Tung, Taiwan. Though these two earthquakes have not caused any tsunami hazard, the tidal gauges near the epicenters did record the incidences of long water waves, similar to tsunami waves. There have not been many seismic records of large submarine earthquakes offshore southwestern Taiwan. As such, people living in the coastal area around Taiwan generally lack alertness for potential tsunami hazards caused by submarine earthquakes. In order to assess the potential tsunami hazards in this region, numerical simulations of the tsunami-wave propagation generated by the two Pingtung submarine earthquakes are conducted in this study. The initial tsunami wave height is assumed to be equal to the seafloor vertical displacement caused by the earthquake, and Harvard CMT source parameters are used to calculate the seafloor vertical displacement using elastic fault model. The water-level records of the available tidal gages are used to validate the simulation results. The effects of the source parameters (source depth, average dislocation, and fault-plane width) on the initial tsunami wave height and the subsequent propagation are also studied. The results indicates that the initial tsunami wave height increases from 0.09 m to 0.4 m and the maximum water level at Hou-Bi-Hu tidal-gauge station increases from 0.2 m 0.4 m, as the source depth decreases from 40 km to 10 km; the initial tsunami wave height increases from 0.02 m to 0.6 m and the maximum water level at Hou-Bi-Hu tidal-gauge station increases from 0.35 m to 1 m, as the average dislocation increases from 1 m to 3 m. The water depths in the southwest region offshore Taiwan are between 2,000 m and 3,000 m, which can result in a large propagation speed of the tsunami wave. Our simulation result indicates that the leading tsunami wave arrives at Heng-Chun coast within 17 min after the quake. This implies that if the same submarine earthquake with a larger magnitude occurs, it would certainly cause devastation to the southwestern coasts of Taiwan. | en_US |