2003 Mw6.8 Chengkung earthquake and its related seismogenic structures, ground deformations, fault rupture inversion
Presenter: Guan-Hao Peng Adviser: Horng-Yuan Yen, Kuochen Hao
Abstract
The Mw = 6.8 Chengkung earthquake on December 10, 2003 in eastern Taiwan was associated with abundant aftershocks. We relocated the aftershocks, determined the focal mechanisms from P-wave polarities and used the FDSM method to identify the fault plane. The earthquake can be divided into three seismic clusters: one is located in the east of the southern Longitudinal Valley show that east-dipping fault planes with thrust mechanisms coincide with previous studies based on background seismicity. One on the Chihshang fault, and the other on the western side of the Luyeh fault to the south. The third seismic cluster suggests thrust mechanism along west-dipping fault plane that was not recognized by background seismicity. This seismic cluster occurred along the Central Range Fault previously proposed as active by geomorphic and geologic evidence. Coseismic ground displacements recorded by strong-motion records allow us to deduce instant rupturing of this event. Our resulting model shows a fault length of ~33 km and dip-slip dominant rupture on fault-plane deeper than 18 km. estimated co-seismic displacements constrain two fault planes: one at 5–18 km depth dipping 60°E and 18–36 km depth dipping 45°E. The uppermost fault-plane of the Chihshang Fault (0–5 km) did not break immediately after the main shock; however, it may have a major role in after-slip and even interseismic ground deformation. The Taiyuan basin developed in the hanging wall is a geomorphic feature consistent with and adequately explained by coseismic ground displacements.
References
Kuochen, H., Wu, Y.M., Chang, C.H., Hu, J.C., Chen, W.S., 2004. Relocation of the eastern Taiwan earthquakes and its tectonic implications. TAO 15, 647–666.
Kuochen, H., Y. M. Wu, Y. G. Chen, and R. Y. Chen., 2006. 2003 Mw6. 8 Chengkung earthquake and its related seismogenic structures, J. Asian Earth Sci., in press.
Y. M. Wu, Y. G. Chen, T. C. Shin, H. Kuochen C. S. Hou, J. C. Hu, C. H. Chang,C. F. Wu, and T. L. Teng, 2006. Coseismic versus interseismic ground deformations, fault rupture inversion and segmentation revealed by 2003 Mw 6.8 Chengkung earthquake in eastern Taiwan. J. Geophys. Res., VOL. 33, L02312, doi: 10.1029/2005GL024711.
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