Tsunami and shaking simulations of potential large subduction zone earthquake along the southernmost Ryukyu Trench
Date Issued
2015
Date
2015
Author(s)
Lin, Tzu-Chi
Abstract
During the last century, many big earthquakes with magnitude larger than 9 had occurred along the subduction zones. For example, the 1960 Chile earthquake (M9.5), the 2004 Sumatra-Andaman earthquake (M9.3), and the 2011 Tohoku earthquake (M9.0). In this study, we focus on the southernmost Ryukyu Trench which is extremely close to northern Taiwan. Interseismic GPS data in northeast Taiwan shows a pattern of strain accumulation suggests that the maximum likely magnitude of a potential future large earthquake in this area is probably about moment magnitude 8.7. In order to evaluate the influence of the potential megathrust event, we consider a 3-D fault plane along this portion of subduction zone at depths shallower than 50 km. We apply the interseismic GPS data to invert the source slip pattern on the subducting fault plane. In addition, several source rupture scenarios with different characterized slip patterns are considered to simulate the ground shaking based on 3-D spectral-element method. We analyze ShakeMap and ShakeMovie from the simulation results to evaluate the influence over the island between different source models. A dispersive tsunami propagation simulation is also carried out to evaluate the maximum tsunami wave height along the coastal areas of Taiwan due to coseismic seafloor deformation of different source models. From the results of all rupture scenarios, the peak ground acceleration larger than 1g can be observed in many areas even though the rupture occurs off northeastern coast of Taiwan. The tsunami simulation results show that the sea level raised significantly along the eastern coast, especially in the offshore area of Ilan where tsunami high can over 20 meters. The results of this numerical simulation study can provide a physically based information of megathrust earthquake scenario for the emergency response agency to take the appropriate action before the really big one happens.
Subjects
Southernmost Ryukyu Trench
large subduction zone earthquake
scenario earthquake,
source inversion
tsunami and shaking simulations
Type
thesis
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