Sustained tsunami-wave excitations and oscillations in the lagoon of a semi-enclosed atoll island in the South China Sea
Coral reef atoll islands have unique vulnerabilities to coastal hazards like tsunamis and storms. Many coral atoll islands, when formed with a volcanic origin, are typically characterized by a conical or sub-conical shape with narrow insular shelves in morphology and low-lying elevations. Although m...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Taylor & Francis Group
2025-12-01
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| Series: | Engineering Applications of Computational Fluid Mechanics |
| Subjects: | |
| Online Access: | https://www.tandfonline.com/doi/10.1080/19942060.2025.2507752 |
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| Summary: | Coral reef atoll islands have unique vulnerabilities to coastal hazards like tsunamis and storms. Many coral atoll islands, when formed with a volcanic origin, are typically characterized by a conical or sub-conical shape with narrow insular shelves in morphology and low-lying elevations. Although many inhabited coral islands are exposed to great tsunami threats, yet very few of them are carefully examined in terms of the potential tsunami impact. Here, we use a semi-enclosed coral reef atoll island in the South China Sea as a typical example to demonstrate tsunami features affecting such coral reef islands. We consider hundreds of earthquake scenarios in the Manila Subduction Zone (MSZ). Our results show that earthquakes from the southern segment of the MSZ generate the highest hazard impact on the studied island than the other segments. Maximum tsunami heights could reach 2.5 m and significantly flood the central and southwestern tip of the island. Our results also reveal an intriguing phenomenon that the bathymetry within the insular shelf plays a key role in shaping wave amplification, oscillations and currents in the lagoon and surrounding areas of the island. Particularly, the plateau-shape shallow water area in the lagoon functions as a basin that traps waves to oscillate for more than 30 h, generating multiple amplified waves (∼1.5 m) in the lagoon and strong currents (>5 m/s) prevalence within shallow water area (<12 m). We further obtain the wave periods of the oscillations are dominated by the dimension of the island along the major axis. We highlight that these bathymetry-associated tsunami impacts are important for coral reef islands to take corresponding hazard mitigation measures to counter potential damages. We call for a detailed investigation of the rest coral reef islands in the SCS and global oceans where the tsunami hazard potential is high. |
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| ISSN: | 1994-2060 1997-003X |