TY - JOUR
T1 - 3-D shear wave velocity structure of the crust and upper mantle in South China Sea and its surrounding regions by surface wave dispersion analysis
AU - Wu, Hsin Hung
AU - Tsai, Yi Ben
AU - Lee, Tung Yi
AU - Lo, Ching Hua
AU - Hsieh, Chao Hui
AU - Toan, Dinh Van
N1 - Funding Information:
We thank the National Science Council for funding this research under the contract number NSC 91-2116 -M-008-010. We also thank Mr. Trinh Viet Bac of the Institute of Geological Sciences, National Center for Natural Sciences and Technology, Hanoi, Vietnam, for helping the data collection at Bacgiang and Vinh City, Vietnam. We thank Dr. Shu-Kun Hsu for valuable suggestions and help. We also thank Dr. Ruey-Der Huang for valuable help.
PY - 2004/3
Y1 - 2004/3
N2 - In this study, we construct a 3-D shear wave velocity structure of the crust and upper mantle in South China Sea and its surrounding regions by surface wave dispersion analysis. We use the multiple filter technique to calculate the group velocity dispersion curves of fundamental mode Rayleigh and Love waves with periods from 14 s to 120 s for earthquakes occurred around the Southeast Asia. We divide the study region (80° E-140° E, 16° S-32° N) into 3° × 3° blocks and use the constrained block inversion method to get the regionalized dispersion curve for each block. At some chosen periods, we put together laterally the regionalized group velocities from different blocks at the same period to get group velocity image maps. These maps show that there is significant heterogeneity in the group velocity of the study region. The dispersion curve of each block was then processed by surface wave inversion method to obtain the shear wave velocity structure. Finally, we put the shear wave velocity structures of all the blocks together to obtain the three-dimensional shear wave velocity structure of crust and upper mantle. The three-dimensional shear wave velocity structure shows that the shear wave velocity distribution in the crust and upper mantle of the South China Sea and its surrounding regions displays significant heterogeneity. There are significant differences among the crustal thickness, the lithospheric thickness and the shear wave velocity of the lid in upper mantle of different structure units. This study shows that the South China Sea Basin, southeast Sulu Sea Basin and Celebes Sea Basin have thinner crust. The thickness of crust in South China Sea Basin is 5-10 km; in Indochina is 25-40 km; in Peninsular Malaysia is 30-35 km; in Borneo is 30-35 km; in Palawan is 35 km; in the Philippine Islands is 30-35 km, in Sunda Shelf is 30-35 km, in Southeast China is 30-40 km, in West Philippine Basin is 5-10 km. The South China Sea Basin has a lithosphere with thickness of about 45-50 km, and the shear wave velocity of its lid is about 4.3-4.7 km/s; Indochina has a lithosphere with thickness of about 55-70 km, and the shear wave velocity of its lid is about 4.3-4.5 km/s; Borneo has a lithosphere with thickness of about 55-60-km, and the shear wave velocity of its lid is about 4.1-4.3 km/s; the Philippine Islands has a lithosphere with thickness of about 55-60 km, and the shear wave velocity of its lid is about 4.2-4.3 km/s, West Philippine Basin has a lithosphere with thickness of about 50-55 km, and the shear wave velocity of its lid is about 4.7-4.8 km/s, Sunda Self has a lithosphere with thickness of about 55-65 km, and the shear wave velocity of its lid is about 4.3 km/s. The Red-River Fault Zone probably penetrates to a depth of at least 200 km and is plausibly the boundary between the South China Block and the Indosinia Block.
AB - In this study, we construct a 3-D shear wave velocity structure of the crust and upper mantle in South China Sea and its surrounding regions by surface wave dispersion analysis. We use the multiple filter technique to calculate the group velocity dispersion curves of fundamental mode Rayleigh and Love waves with periods from 14 s to 120 s for earthquakes occurred around the Southeast Asia. We divide the study region (80° E-140° E, 16° S-32° N) into 3° × 3° blocks and use the constrained block inversion method to get the regionalized dispersion curve for each block. At some chosen periods, we put together laterally the regionalized group velocities from different blocks at the same period to get group velocity image maps. These maps show that there is significant heterogeneity in the group velocity of the study region. The dispersion curve of each block was then processed by surface wave inversion method to obtain the shear wave velocity structure. Finally, we put the shear wave velocity structures of all the blocks together to obtain the three-dimensional shear wave velocity structure of crust and upper mantle. The three-dimensional shear wave velocity structure shows that the shear wave velocity distribution in the crust and upper mantle of the South China Sea and its surrounding regions displays significant heterogeneity. There are significant differences among the crustal thickness, the lithospheric thickness and the shear wave velocity of the lid in upper mantle of different structure units. This study shows that the South China Sea Basin, southeast Sulu Sea Basin and Celebes Sea Basin have thinner crust. The thickness of crust in South China Sea Basin is 5-10 km; in Indochina is 25-40 km; in Peninsular Malaysia is 30-35 km; in Borneo is 30-35 km; in Palawan is 35 km; in the Philippine Islands is 30-35 km, in Sunda Shelf is 30-35 km, in Southeast China is 30-40 km, in West Philippine Basin is 5-10 km. The South China Sea Basin has a lithosphere with thickness of about 45-50 km, and the shear wave velocity of its lid is about 4.3-4.7 km/s; Indochina has a lithosphere with thickness of about 55-70 km, and the shear wave velocity of its lid is about 4.3-4.5 km/s; Borneo has a lithosphere with thickness of about 55-60-km, and the shear wave velocity of its lid is about 4.1-4.3 km/s; the Philippine Islands has a lithosphere with thickness of about 55-60 km, and the shear wave velocity of its lid is about 4.2-4.3 km/s, West Philippine Basin has a lithosphere with thickness of about 50-55 km, and the shear wave velocity of its lid is about 4.7-4.8 km/s, Sunda Self has a lithosphere with thickness of about 55-65 km, and the shear wave velocity of its lid is about 4.3 km/s. The Red-River Fault Zone probably penetrates to a depth of at least 200 km and is plausibly the boundary between the South China Block and the Indosinia Block.
KW - 3-D shear wave velocity structure
KW - Constrained block inversion method
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U2 - 10.1007/s11001-005-0730-8
DO - 10.1007/s11001-005-0730-8
M3 - Article
AN - SCOPUS:25844477434
SN - 0025-3235
VL - 25
SP - 5
EP - 27
JO - Marine Geophysical Research
JF - Marine Geophysical Research
IS - 1-2
ER -