TY - JOUR
T1 - Interactions between Dongsha Atoll and Mw 9 Tsunamis and their Impacts in South China Sea Region
AU - Wang, Jinghua
AU - Liu, Philip L.F.
N1 - Funding Information:
The authors want to thank Prof. Yang-Yih Chen at National Sun Yat-sen University for providing the bathymetry and topography data for the Dongsha Island. The authors also show gratitude to Prof. Kai Meng Mok at University of Macau for providing the topo-bathymetry data of Macau. The numerical model used the topobathymetry information of Hong Kong that can be requested from Hydrographic O ce of the Marine Department of Hong Kong (http://www.hydro.gov.hk) and Civil Engineering and Development Department of Hong Kong (http://www.hyd. gov.hk). The GEBCO 30 arc sec bathymetry data is freely available at the General Bathymetric Chart of the Oceans website (http://www.gebco.net/). The authors also want to thank Dr. Ignacio Sep lveda at San Diego State University for providing the earthquake data for tsunami wave initiation in this study. The authors acknowledge the support of a research grant from the National Research Foundation Singapore to the National University of Singapore (Award number: NRF2018NRFNSFC003ES- 002). PLF Liu would also like to acknowledge the support through the Yushan Scholar Program, awarded by the Ministry of Education in Taiwan.
Publisher Copyright:
© 2022 World Scientific Publishing Company.
PY - 2022/6/1
Y1 - 2022/6/1
N2 - Tsunamis induced by megathrust in the Manila subduction zone impose alarming threats to the coastal cities in the northern South China Sea (SCS), and risk assessment of tsunami hazards in this region becomes demanding. One distinguishable geographic feature in this region is Dongsha Atoll, which is situated between the tsunami source zone and the China coastline. This study discusses the role of the Dongsha Atoll in modifying the tsunami impacts through numerical simulations of a group of synthetic tsunami events with Mw=9. Three types of representations for the Atoll in the numerical simulations are employed, specifically (i) the real topo-bathymetry of the Atoll is fully resolved (Model-1), (ii) the Atoll is removed (Model-2), and (iii) the Atoll is artificially represented by a cylinder (Model-3). The results show that without the Dongsha Atoll presence (Model-2), the tsunamis can induce a substantial increment of water level behind the Atoll and in the vicinity of the Pearl River Delta (PRD) region in China. While the results obtained by realistically modeling the Atoll (Model-1) show that a large amount of tsunami wave energy/momentum can be entrapped by the lagoon and slowly radiated to the ocean. The interactions between the tsunamis and the Atoll will lead to severe flooding on the Dongsha Island on the west bank of the Atoll. However, the peak water levels behind the Atoll and at the selected mainland coastal sites are reduced, indicating that the Dongsha Atoll can offer some degree of protection for the region in its behind. Meanwhile, a slightly smaller reduction of tsunami heights is reported in the simulations with the Atoll being represented by a cylinder (Model-3), implying that the reduction effects are sensitive to the representations of the Atoll. Therefore, the full model of the topo-bathymetry of the Dongsha Atoll is recommended for future tsunami risk assessments for both Dongsha Atoll and the mainland in the SCS region.
AB - Tsunamis induced by megathrust in the Manila subduction zone impose alarming threats to the coastal cities in the northern South China Sea (SCS), and risk assessment of tsunami hazards in this region becomes demanding. One distinguishable geographic feature in this region is Dongsha Atoll, which is situated between the tsunami source zone and the China coastline. This study discusses the role of the Dongsha Atoll in modifying the tsunami impacts through numerical simulations of a group of synthetic tsunami events with Mw=9. Three types of representations for the Atoll in the numerical simulations are employed, specifically (i) the real topo-bathymetry of the Atoll is fully resolved (Model-1), (ii) the Atoll is removed (Model-2), and (iii) the Atoll is artificially represented by a cylinder (Model-3). The results show that without the Dongsha Atoll presence (Model-2), the tsunamis can induce a substantial increment of water level behind the Atoll and in the vicinity of the Pearl River Delta (PRD) region in China. While the results obtained by realistically modeling the Atoll (Model-1) show that a large amount of tsunami wave energy/momentum can be entrapped by the lagoon and slowly radiated to the ocean. The interactions between the tsunamis and the Atoll will lead to severe flooding on the Dongsha Island on the west bank of the Atoll. However, the peak water levels behind the Atoll and at the selected mainland coastal sites are reduced, indicating that the Dongsha Atoll can offer some degree of protection for the region in its behind. Meanwhile, a slightly smaller reduction of tsunami heights is reported in the simulations with the Atoll being represented by a cylinder (Model-3), implying that the reduction effects are sensitive to the representations of the Atoll. Therefore, the full model of the topo-bathymetry of the Dongsha Atoll is recommended for future tsunami risk assessments for both Dongsha Atoll and the mainland in the SCS region.
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U2 - 10.1142/S1793431122400012
DO - 10.1142/S1793431122400012
M3 - Article
AN - SCOPUS:85129826540
SN - 1793-4311
VL - 16
JO - Journal of Earthquake and Tsunami
JF - Journal of Earthquake and Tsunami
IS - 3
M1 - 2240001
ER -