Using geodetic and seismic data to model the coseismic dislocation of the 1951 Hualien-Taitung earthquake sequence
Presenter: Ting-Yu Liu Adviser: Wu-Lung Chang, Chung-Pai Chang
Abstract
The Longitudinal Valley Fault (LVF) in eastern Taiwan is an extremely active fault with 3–4 cm of displacements consumed each year along its length. The fault forms the suture zone between the Philippine Sea and Eurasian plates as a result of an oblique arc-continental collision. From 22 October to 5 December 1951, four earthquakes (ML> 7) shook the LVF. (Lee et al., 2008) used triangulation (from 1917 to 1921 to 1976–1978) and interseismic GPS (1990–1995) data to estimate coseismic displacements of the 1951 earthquake sequences by Poly3D software [Thomas, 1993]. Another research done by (Chung et al., 2008) used the same dataset with (Lee et al., 2008) but had different approach with the datasets. By recomputing the archive triangulation datasets (1917–1978) with a correction value, and extrapolated the horizontal displacement from GPS (1992–1999), then using a dislocation algorithm to determine the coseismic displacement model with three fault segments. Both model results are consistent with the observation of the 1951 M7.3 Hualien–Taitung earthquake sequence: that the southern segment is oblique-slip fault with significant thrust components, while the northern segment is a pure strike-slip fault. With regard to the central segment, the epicenter distribution of catalogued earthquakes occurring after 1951 reveals the presence of a seismic gap, indicating that slip on this segment is predominantly coseismic, with a correspondingly higher potential for large earthquakes in the future.
References
Lee, Y. H., G. T. Chen, R. J. Rau, and K.-E. Ching (2008), Coseismic displacement and tectonic implication of 1951 Longitudinal Valley earthquake sequence, eastern Taiwan, J. Geophys. Res., 113, B04305, doi:10.1029/2007JB005180.
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Chung, L.H., Y.G. Chen, Y.M. Wu, J.B.H. Shyu, Y.T. Kuo, Y.N.N. Lin, (2008) Seismogenic faults along the major suture of the plate boundary deduced by dislocation modeling of coseismic displacements of the 1951 M7.3 Hualien-Taitung earthquake sequence in eastern Taiwan, Earth Planet. Sci. Lett., 269 (3–4) (2008), pp. 416–426