Rayleigh Wave Phase Velocity Maps of Southwest Yunnan Based on Ambient Noise Tomography 基于背景噪声的滇西地区瑞利面波相速度成像

Zhang，Yi1,3; Guo，Zhen2,3; Zhu，Pei Yu1; Zhu，Jia Miao1; Dai，Le Xiang1

2023

10.12196/j.issn.1000.3274.2023.01.010

Earthquake   Impact Factor & Quartile

1000-3274

In this paper, the phase velocity distribution images of Southwest Yunnan (21. 0°N~29. 5°N, 97. 0°E~103. 5°E) are obtained with continuous seismic records at 190 mobile stations in the first periods of ChinArray (2011-01 - 2014-06) and 35 broadband permanent stations of Yunnan regional network. The ChinArray was setup in the southeast of the Qinghai-Xizang Plateau. Inversion results reveal significant lateral heterogeneity in the velocity structure of the crust and upper mantle in the study area. Short period images (6~12 s) indicate a strong correlation between upper crust velocity and surface geological structures. The low velocity anomaly in Tengchong volcanic area and its southern side is related to the magmatic sac or partial melt in the upper crust, and the shape is different in depth. A high-velocity anomaly is observed between Chenghai fault and Puduhe fault, consistent with the body wave travel time inversion results. The inversion indicates a large high-velocity anomaly in Panxi area, potentially related to basalt uplift in this area. Phase velocity images with periods of 14 ~ 25 s reveal low-velocity anomalies in the Sichuan-Yunnan rhombic block and Tengchong volcanic area, suggesting the presence of lower crustal flow. Comparing 14~40 s images, due to variations in crustal thickness, the high-velocity anomaly gradually increases in the southern region. Furthermore, the low-velocity anomaly in the Tengchong volcanic area extends from the surface to the upper mantle, but it does not appear to be continuous with the low velocity anomaly in the Sichuan-Yunnan rhombic block. This low velocity anomaly may be a channel of mantle heat flow. The intersection of the Tengchong fault and Longling fault appears to be the boundary between high and low-velocity anomalies. Two M≥7 earthquakes in 1976 may occurred beneath this area.

Ambient noise tomography Crustal structure Phase velocity Southwest Yunnan Area

Chinese

Others

2-s2.0-85160922895

Scopus

1.Shanghai Seismological Bureau,Shanghai,200062,China
2.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
3.Shanghai Sheshan National Geophysical Observatory,Shanghai,200062,China

Zhang，Yi,Guo，Zhen,Zhu，Pei Yu,等. Rayleigh Wave Phase Velocity Maps of Southwest Yunnan Based on Ambient Noise Tomography 基于背景噪声的滇西地区瑞利面波相速度成像[J]. Earthquake,2023,43(1):124-136.

Zhang，Yi,Guo，Zhen,Zhu，Pei Yu,Zhu，Jia Miao,&Dai，Le Xiang.(2023).Rayleigh Wave Phase Velocity Maps of Southwest Yunnan Based on Ambient Noise Tomography 基于背景噪声的滇西地区瑞利面波相速度成像.Earthquake,43(1),124-136.

Zhang，Yi,et al."Rayleigh Wave Phase Velocity Maps of Southwest Yunnan Based on Ambient Noise Tomography 基于背景噪声的滇西地区瑞利面波相速度成像".Earthquake 43.1(2023):124-136.