Deterministic tsunami hazard assessment and zoning approach using far-field and near-field sources: Study of Cixi County of Zhejiang Province, China

Abstract

Investigating the potential tsunami hazard for coastal regions is helpful for urban development and emergency evacuation. In this paper, we present a deterministic method for tsunami hazard assessment (DTHA) in terms of tsunami amplitude and tsunami-induced currents. 21 extreme far-field transoceanic tsunami sources located in the Pacific Rim and, 14 near-field sources in Ryukyu Trough and Manila Trench are suggested. The Digital Elevation Model (DEM) data of 50 m combined with coastal breakwater data is adopted. The tsunami hazard is analyzed based on tsunami amplitude and tsunami-induced velocity. The coastal risk of Cixi County is presented and discussed. The results highlight the necessity of combining the tsunami amplitude and tsunami-induced currents in hazard assessment with the protective role of breakwaters. Further study manifests the effects of astronomical tide on tsunami hazard. The submarine topography consisted of ridges and trenches could trap tsunami energy and change propagation direction. The heterogeneous effect of slip distribution on tsunami hazard assessment is investigated, indicating the feasibility of using uniform slip source in DTHA. This study provides a comprehensive and quantitative assessment method incorporating tide, DEM, breakwater, and multiple sources to evaluate the tsunami risk for hazard reduction and urban planning.