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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhess-2017-336
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
06 Nov 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Assessment of peak tsunami amplitude associated with a great earthquake occurring along the southernmost Ryukyu subduction zone for Taiwan region
Yu-Sheng Sun1, Po-Fei Chen1, Chien-Chih Chen1, Ya-Ting Lee1, Kuo-Fong Ma1, and Tso-Ren Wu2 1Department of Earth Sciences, National Central University, Taoyuan City, Taiwan 320, R.O.C.
2Graduate Institute of Hydrological and Oceanic Sciences, National Central University, Taoyuan City, Taiwan 320, R.O.C.
Abstract. The southernmost portion of the Ryukyu Trench closed to Taiwan island is a potential region to generate 7.5 to 8.7 tsunami earthquakes by shallow rupture. The fault model for this potential region dips 10º northward with rupture length of 120 km and width of 70 km. The earthquake magnitude estimated by fault geometry is Mw 8.15 with 8.25 m average slip as a constrain of earthquake scenario. The heterogeneous slip distributions over rupture surface are generated by stochastic slip model, the slip spectrum with k-2 decay in wave number domain, and they are consistent with above identical seismic conditions. The results from tsunami simulation illustrate that the propagation of tsunami waves and the peak wave heights largely vary in response to the slip distribution. The wave phase changing is possible as the waves propagate, even under the same seismic conditions. The tsunami energy path is not only following the bathymetry but also depending on slip distribution. The probabilistic distributions of peak tsunami amplitude calculated by 100 different slip patterns from 30 recording stations reveal the uncertainty decreases with distance from tsunami source. The highest wave amplitude for 30 recording points is 7.32 m at Hualien for 100 different slips. Comparing with stochastic slips, uniform slip distribution will be extremely underestimated, especially in near field. In general, uniform slip assumption only represents the average phenomenon so that it will ignore possibility of tsunami wave. These results indicate that considering effect of heterogeneous slip distribution is necessary for assessing tsunami hazard and that can provide more information about tsunami uncertainty for a more comprehensive estimation.

Citation: Sun, Y.-S., Chen, P.-F., Chen, C.-C., Lee, Y.-T., Ma, K.-F., and Wu, T.-R.: Assessment of peak tsunami amplitude associated with a great earthquake occurring along the southernmost Ryukyu subduction zone for Taiwan region, Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2017-336, in review, 2017.
Yu-Sheng Sun et al.
Yu-Sheng Sun et al.
Yu-Sheng Sun et al.

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Short summary
Taiwan at the convergent boundary is possibly threatened from tsunami. The different slip distributions is invoked to describe the uncertainty of the rupture pattern over the fault plane. The heterogeneous slip induces variability in tsunami wave heights and the associated paths of propagation. The peak tsunami amplitude distribution provides a specific range for wave height and its frequency for this scenario. However, the uniform slip assumption only represents the average phenomenon.
Taiwan at the convergent boundary is possibly threatened from tsunami. The different slip...
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