| dc.description.abstract | The March 17, 1906 (UTC) M 7.1 Meishan earthquake is one of the most devastating events in Taiwan’s history. The investigation in the past 100 years on this large event is rather limited due to the lack of seismic observation. However, with the advent of numerical simulations, dynamic rupture modeling provides an additional technique to understand source properties and the rupture process of the Meishan earthquake.
In this study, the primary target is to revisit the source and assess the dynamic parameters for the 1906 Meishan earthquake. Based on physical and mathematical constraints from frictional limit, fault geometries, fluid pressure, rock strength, empirical flow law, static friction coefficient, and stress drop, I build up 192 models for the experiment. The models are run in the linear slip-weakening model and on a 3D finite element mesh in a homogeneous half-space. By comparison of the resulting rupture conditions from the suite of ruptured models, I discuss the possible ranges of dynamic parameters for the historical earthquake. Following the selection of the most reasonable models, I compare the polarities and amplitudes of the synthetic waveforms to the waveforms observed on Omori seismographs in addition to the intensity maps in conjunction with the distribution of the aftershocks of the 1906 Meishan earthquake.
Resulting rupture processes show that the static friction coefficient ranges from 0.4 to 0.5, implying that Byerlee’s law does not hold for the region. Average stress drops in our models are in the range of few to few tens of MPa, and is in range of stress drops of similarly sized earthquakes in Taiwan. Fluid overpressurization weakens the rock matrices, and therefore, during rupture expands area and increases slip. According to the rupture process, waveform comparison, and seismic intensity simulation, the results provide considerably well-fit polarities and amplitudes from waveforms and similar intensity patterns with historical intensity maps for multiple-segment models. This study indicates that rupture occurred on multiple faults connected to the Meishan fault rather than on the Meishan fault alone. The results in this study suggest that the Meishan earthquake with its thrust fault association is closer in its faulting characteristics to other major events in western Taiwan, such as the 1999 Chi-Chi earthquake, due to this not yet widely considered thrust component. | en_US |