How heterogeneous coseismic slip affects regional probabilistic tsunami hazard assessment: A case study in the South China Sea

Abstract

Rupture complexity, typically in the form of heterogeneous slip distribution pattern, significantly affects the local tsunami wave field. However, the effect of rupture complexity is not commonly considered in any form of tsunami hazard assessment. Taking rupture complexity into account significantly increases the computational load, particularly in regional‐scaled probabilistic tsunami hazard assessments (PTHAs) that usually require a large number of simulations based on synthetic scenarios. In this study, we investigate how the heterogeneous slip distribution affects the regional‐scaled PTHA by taking the South China Sea (SCS) as an example. By doing this, we update PTHA for the SCS by incorporating the best available information of seismic tsunamigenic sources along the Manila megathrust. We integrate a stochastic source model into a Monte Carlo‐type simulation, in which a broad range of slip distribution patterns is generated for large numbers of synthetic earthquake events. Green's function technique is employed to efficiently calculate the nearshore tsunami wave amplitude along the SCS coastlines. Our result suggests that for a relatively small and confined region like the SCS, the commonly used approach based on the uniform slip model significantly underestimates tsunami hazard not only in the near‐source region like west Luzon, as expected, but also in the relative far field, such as south China and central Vietnam. Additionally, our sensitivity test of the patch size effects suggests that large patch size is unable to adequately resolve the details of heterogeneous seafloor deformation, and such approaches considerably underestimate the potential tsunami hazard for the SCS coasts.

Prediction of Tsunami Waves by Uniform Slip Models

“…For local tsunami hazard assessment, it is now a popular approach to account for uncertainties in earthquake slip distributions. Given a potential earthquake of presumed magnitude, different slip distributions can be generated with different probabilities (Mai & Beroza, ), and they result in different tsunami wave heights at coastal regions (Geist, ; Goda et al, , ; LeVeque et al, ; Li et al, ; Sepúlveda et al, ). Here we point out that the fact of tsunamis depending on slip distributions is not contradictory to our results.…”

Occurrence of 1 ka-old corals on an uplifted reef terrace in west Luzon, Philippines: Implications for a prehistoric extreme wave event in the South China Sea region

“…The eastdipping discontinuous Manila-Negros-Sulu-Cotabato Trench system and the west-dipping Philippine Trench system are potential sources of large magnitude offshore earthquakes which pose imminent threats to lives and properties along coastal communities (Li et al 2016;Ramos and Tsutsumi 2010;Besana et al 2004; Fig. 1).…”

“…Of particular interest in the Southeast Asian region is the tsunami-generation potential of the Manila Trench which poses risks to coastal zones across the South China Sea (SCS). Over the years, the tsunami-generation potential of the Manila Trench has been highlighted in the tsunami hazard assessments of Taiwan, Thailand, China, Vietnam, Malaysia, Singapore, and Philippines [e.g., (Dao et al 2009;Huang et al 2009;Liu et al 2009;Megawati et al 2009;Ruangrassamee and Saelem 2009;Wu and Huang 2009;Nguyen et al 2014;Li et al 2016)]. In the Philippines, recent efforts in tsunami studies involve characterization of source faults through validation of historical and modern tsunami observations [e.g., (Bautista et al 2012;Salcedo 2014)].…”

Tsunamigenic Potential of the Baiyun Slide Complex in the South China Sea

“…The tsunami hazard research in the South China Sea (SCS) has been mostly focused on megathrust earthquakes along the Manila Trench, which is believed to be the primary tsunami source capable of generating basin‐wide tsunami (e.g., L. Li, Switzer, et al, ; L. Li et al, ; Liu et al, ; Megawati et al, ; Sepúlveda et al, ; Terry et al, ). However, recent activity in submarine exploration has produced high‐resolution bathymetric and 2‐D/3‐D seismic data that reveal hundreds of submarine landslides in the continental slopes of the SCS including those observed in the Pearl River Mouth Basin (Chen et al, ; He et al, ; W. Li, Wu, Völker, et al, ; Sun, Alves, et al, ; Sun, Cartwright, et al, ; Sun et al, ; Sun et al, ; Wang et al, ; Wu et al, ), offshore southwest Taiwan (Su et al, ), southeast Hainan (e.g.…”