利用密集台阵近震层析成像研究云南宾川上地壳速度结构

Translated title of the contribution: Upper crustal velocity structure of Binchuan, Yunnan revealed by dense array local seismic tomography

Yunpeng Zhang, Baoshan Wang, Guoqing Lin, Weitao Wang, Wei Yang, Zhonghai Wu

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The Binchuan basin, located in northwestern of Yunnan Province, is a large Late Cenozoic rift basin at the intersection of the Red River fault and Chenghai fault. The faults are well developed and the seismicity is very active in this area. Studying the fine structure of the upper crust and basin in Binchuan is important to understand the characteristics from deep to shallow of the main seismic structures in this area. Based on the dense array observation experiment around Binchuan basin for two months in 2017, we picked 117221 P-wave and 5475 S-wave first arrivals from 96 small local earthquakes, and performed earthquake relocation and body-wave tomography using the simul2000 program. The obtained results show that (1) the earthquakes in the Binchuan basin are concentrated at the turning area of the Binchuan basin eastern margin fault and show a banding distribution along the NE trending fault on the southern edge of the Erhai Lake, which indicate that NS-NE trending faults are the main seismic control structures and the NW trending faults are the secondary. (2) The velocity distribution at 0 km has a good correspondence with local topography, with high-velocity anomalies in the mountains and low-velocity anomalies in the Binchuan basin. From 3 km to 9 km, the high-low velocity boundaries correspond well to local faults. The controlling effect in the upper crustal structure of the Binchuan basin eastern margin fault (near NS-NNE trending) becomes more and more obvious with depth. (3) Our results also reveal that the dipping angle of Binchuan basin eastern margin fault is large in the northern and the southern portions, however, is gentle in the middle portion, reflecting the rotation characteristics of the regional tectonic block. (4) Relocation and tomographic results indicate that near NS and NNE trending faults are gradually replacing the NW trending faults as the main boundary faults and the main seismic control structures. Our new study results provide an important reference to better understand the main seismic-controlling structures and their deep structural features.

Translated title of the contributionUpper crustal velocity structure of Binchuan, Yunnan revealed by dense array local seismic tomography
Original languageChinese (Traditional)
Pages (from-to)3292-3306
Number of pages15
JournalActa Geophysica Sinica
Volume63
Issue number9
DOIs
StatePublished - Sep 1 2020

Keywords

  • Airgun
  • Binchuan
  • Body-wave tomography
  • Chenghai fault
  • Earthquake relocation

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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