| dc.description.abstract | Source scaling, the relation between source parameters earthquake size, has been explored the self-similarity relation or developed a series of empirical relationships from the beginning of 1970s. In general, an important requirement for probabilistic and deterministic analyses in seismic hazard of engineering seismology is to estimate a future earthquake potential in a specific region. The fault parameters (e.g. fault length, width and mean slip) generated by a particular fault or earthquake source related to the size of the largest earthquakes is often necessary. In addition, pre-setting source dimensions and slip over the fault are also necessary for numerical prediction of time history ground motion. This kind of studies, thus, not only focuses on scientific purposes for seismology but provides the implications and applications for engineering seismology.
Source parameters, including fault length, width and mean slip can be dug out from the finite-fault slip distribution inferred from waveform inversion. In this study, thus, we sorted and solved slip distribution models resolved from the period from 1993 to 2009 in Taiwan. We investigated the source scaling of earthquakes (Mw4.6~Mw7.7) from Taiwan orogenic belt, and made the global compilation of source parameter to discuss the scaling self-similarity. Finite-fault slip models (13 dip-slip and 7 strike-slip) using mainly from Taiwan dense strong motion and teleseismic data were utilized. Seven additional earthquakes (M>7) were included for further scaling discussion on large events. Considering the definitive effective length and width for the scaling study, we found M0~L^2 and M0~L^3 for the events less and larger than the seismic moment of 10^20 Nm, respectively, regardless the fault types, suggesting a non-self similar scaling for small to moderate events and a self-similar scaling for large events. Although the events showed the variation in stress drops, except three events with high stress drops, most of the events had the stress drops of 10-100 bars. The bilinear relation was well explained by the derived magnitude-area equation of Shaw (2009) while we considered only the events with the stress drops of 10-100 bars and the seismogenic thickness of 35 km. The bilinear feature of the regressed magnitude-area scaling appears at the ruptured area of about 1000 km^2, for our seismogenic thickness of 35 km. For the events having ruptured area larger than that, the amount of the average slip becomes proportional to the ruptured length.
The distinct high stress drops events from blind faults in the western foothill of Taiwan yield local high Peak Ground Acceleration (PGA) as we made the comparison to the Next Generation Attenuation (NGA) model. Further, we implemented strong motion waveform modeling with the empirical Green’s function method to assess the area of strong-motion generation for inspecting the existence of fact that two earthquakes with similar magnitude have significantly distinct stress drop. Two earthquakes with similar magnitude have ~180 and ~610 bars, respectively, indeed, suggesting that significant difference of stress drop was proved. Regardless the relative small in magnitudes of these events, the high PGA of these events will give the high regional seismic hazard potential, and, thus, required special attention for seismic hazard mitigation.
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