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

Hsin Hung Wu, Yi Ben Tsai, Tung Yi Lee, Ching Hua Lo, Chao Hui Hsieh, Dinh Van Toan

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)5-27
Number of pages23
JournalMarine Geophysical Research
Volume25
Issue number1-2
DOIs
Publication statusPublished - 2004 Mar

Keywords

  • 3-D shear wave velocity structure
  • Constrained block inversion method

ASJC Scopus subject areas

  • Oceanography
  • Geophysics
  • Geochemistry and Petrology

Fingerprint Dive into the research topics of '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'. Together they form a unique fingerprint.

  • Cite this