Review of "Revised earthquake sources along Manila Trench for tsunami hazard assessment in the South China Sea"

Abstract. Seismogenic tsunami hazard assessments are highly dependent on the reliability of earthquake source models. Here in a study of the Manila subduction zone (MSZ) system, we combine the geological characteristics of the subducting plate, geometry, and coupling state of the subduction interface to propose a series of fault rupture scenarios. We divide the subduction zone into three rupture segments: 14–16, 16–19, and 19–21.7∘ N inferred from geological structures associated with the down-going Sunda plate. Each of these segments is capable of generating earthquakes of a magnitude between Mw=8.5+ and Mw=9+, assuming a 1000-year seismic return period as suggested by previous studies. The most poorly constrained segment of the MSZ lies between 19 and 21.7∘ N, and here we use both local geological structures and characteristics of other subduction zone earthquakes around the world, to investigate the potential rupture characteristics of this segment. We consider multiple rupture modes for tsunamigenic earthquake and megathrust-splay fault earthquakes. These rupture models facilitate an improved understanding of the potential tsunami hazard in the South China Sea (SCS). Hydrodynamic simulations demonstrate that coastlines surrounding the SCS could be devastated by tsunami waves up to 10 m if large megathrust earthquakes occur in these segments. The regions most prone to these hazards include west Luzon of Philippines, southern Taiwan, southeastern China, central Vietnam, and Palawan Island.

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Tsunami hazard from the subduction Megathrust of the South China Sea: Part II. Hydrodynamic modeling and possible impact on Singapore

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2008.08.007 ◽

2009 ◽

Vol 36 (1) ◽

pp. 93-97 ◽

Cited By ~ 17

Author(s):

Zhenhua Huang ◽

Tso-Ren Wu ◽

Soon Keat Tan ◽

Kusnowidjaja Megawati ◽

Felicia Shaw ◽

...

Keyword(s):

South China Sea ◽

South China ◽

Hydrodynamic Modeling ◽

Tsunami Hazard ◽

The South China Sea ◽

The South ◽

China Sea

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Geophysics Appearance of The South China Sea

INDONESIAN JOURNAL OF APPLIED PHYSICS ◽

10.13057/ijap.v11i2.50114 ◽

2021 ◽

Vol 11 (2) ◽

pp. 223

Author(s):

Eddy Mirnanda

Keyword(s):

South China Sea ◽

South China ◽

Bouguer Anomaly ◽

The South China Sea ◽

Crustal Rock ◽

The South ◽

Sunda Shelf ◽

China Sea ◽

Manila Trench ◽

Free Air

South China Sea (SCS) is underlain by sediments of an average density 2.10 g/cm3 of 2 km thickness at its central part up to 10 km in the margins. The basement rock is the upper and lower crust of densities 2.67 and 2.85 g/cm3 respectively of varying thicknesses. The thinnest crustal rock is at the centre of SCS that is called the South China Sea Basin (SCSB). The Mohorovicic discontinuity is about 15 km depth below the SCSB. Heatflow values in this basin vary from 2 to 3.5 HFU.Lineations of total magnetic anomaly are generally in a west-east direction covering the whole study area. However, an elongated northeast-southwest lineation of dipole anomaly separates the west-east anomaly patterns in the north from those in the south. This feature is also observed in the gravity map. These elongated patterns of the total magnetic features are in coincident with the occurrences of seamounts inferred being remnant of extinct seafloor spreading. Because of this spreading a crustal extension had taken place that separated Kalimantan from the mainland of China to restore its present position. A paleomagnetic study result confirms this hypothesis.The Palawan trench is marked by north-east trending magnetic and gravity anomaly that is inferred being traces of a remnant subduction zone. This anomaly forms a boundary between the Zengmu also called the Sarawak basin and the SCSB. Here, heat flow value is 1 to 2 HFU. This value in coincident with gravity gradient of 2.5 mGal/km also represents an active subduction of the Manila trench north of the Palawan Island. The Manila trench is supposed to be the energizing source of volcanism and earthquake in the Phillippines. Free-air and Bouguer anomaly of the order of 50 to 60 mGal and magnetic of about 100 nT represent the Zengmu basin in the Sunda Shelf. This basin is underlain by sediments of 2.10 g/cm3 of 8 km thickness and also crustal rock which is much thicker than the one underneath the SCSB. Strong topographic relief at the surfaces of sedimentary layer and the crustal rock is very my much associated with normal faulting that may cause fluctuation of the free-air values.The continental margins of Sarawak and the Sunda Shelf are areas of hydrocarbon deposits now still in production, whereas the offshores Vietnam and Hainan are promising target for hydrocarbon exploration.

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Revised earthquake sources along Manila Trench for tsunami hazard assessment in the South China Sea

10.5194/nhess-2019-116 ◽

2019 ◽

Author(s):

Qiang Qiu ◽

Linlin Li ◽

Ya-Ju Hsu ◽

Yu Wang ◽

Chung-Han Chan ◽

...

Keyword(s):

South China Sea ◽

Subduction Zone ◽

South China ◽

Tsunami Hazard ◽

The South China Sea ◽

The South ◽

Geological Structures ◽

Tsunami Waves ◽

China Sea ◽

Megathrust Earthquakes

Abstract. Seismogenic tsunami hazard assessments are highly dependent on the reliability of earthquake source models. Here in a study of the Manila subduction zone (MSZ) system, we combine the geological characteristics of the subducting plate, the geometry, and coupling state of the subduction interface to propose a series of fault rupture scenarios. We divide the subduction zone into three rupture segments: 14° N–16° N, 16° N–19° N and 19° N–21.7° N inferred from geological structures associated with the down-going Sunda plate. Each of these segments is capable of generating earthquakes of magnitude between Mw 8.5+ and Mw 9+, assuming a-1000-year seismic return period as suggested by previous studies. The most poorly constrained segment of the MSZ lies between 19° N–21.7° N, and here we use both local geological structures and characteristics of other subduction zone earthquakes around the world, to investigate the potential rupture characteristics of this segment. We consider multiple rupture modes for tsunamigenic-earthquake type and megathrust-splay fault earthquakes. These rupture models facilitate an improved understanding of the potential tsunami hazard in the South China Sea (SCS). Hydrodynamic simulations demonstrate that coastlines surrounded the SCS could be devastated by tsunami waves up to 10-m if large megathrust earthquakes occur in these segments. The regions most prone to these hazards include west Luzon of Philippines, southern Taiwan, the southeastern China, central Vietnam and the Palawan Island.

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