Evaluation of crustal inhomogeneity parameters in the southern Longmenshan fault zone and adjacent regions

AbstractBroadband teleseismic waveform data from 13 earthquakes recorded by 70 digital seismic stations were selected to evaluate the inhomogeneity parameters of the crustal medium in the southern Longmenshan fault zone and its adjacent regions using the teleseismic fluctuation wavefield method. Results show that a strong inhomogeneity exists beneath the study region, which can be divided into three blocks according to its structure and tectonic deformation features. These are known as the Sichuan-Qinghai Block, the Sichuan-Yunnan Block, and the Mid-Sichuan Block. The velocity fluctuation ratios of the three blocks are approximately 5.1%, 3.6%, and 5.1% in the upper crust and 5.1%, 3.8%, and 4.9% in the lower crust. The inhomogeneity correlation lengths of the three blocks are about 10.1 km, 14.0 km, and 10.7 km in the upper crust and 11.8 km, 17.0 km, and 11.8 km in the lower crust. The differences in the crustal medium inhomogeneity beneath the Sichuan-Yunnan Block, the Sichuan-Qinghai Block, and the Mid-Sichuan Block may be related to intensive tectonic movement and material flow in the crust and upper mantle.

Download Full-text

Evaluation of the geothermal parameters to decipher the thermal structure of the upper crust of the Longmenshan fault zone derived from borehole data

Geothermics ◽

10.1016/j.geothermics.2021.102268 ◽

2022 ◽

Vol 98 ◽

pp. 102268

Author(s):

Jar Ullah ◽

Miao Luo ◽

Umar Ashraf ◽

Heping Pan ◽

Aqsa Anees ◽

...

Keyword(s):

Fault Zone ◽

Thermal Structure ◽

Upper Crust ◽

Borehole Data ◽

Longmenshan Fault Zone ◽

Longmenshan Fault ◽

Geothermal Parameters

Download Full-text

Seismic Structure of Local Crustal Earthquakes beneath the Zipingpu Reservoir of Longmenshan Fault Zone

International Journal of Geophysics ◽

10.1155/2011/407673 ◽

2011 ◽

Vol 2011 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Haiou Li ◽

Xiwei Xu ◽

Wentao Ma ◽

Ronghua Xie ◽

Jingli Yuan ◽

...

Keyword(s):

Fault Zone ◽

Three Dimensional ◽

P Wave ◽

The Tibetan Plateau ◽

Seismic Structure ◽

Infiltration Depth ◽

Low Velocity ◽

Longmenshan Fault Zone ◽

Velocity Models ◽

Longmenshan Fault

Three-dimensional P wave velocity models under the Zipingpu reservoir in Longmenshan fault zone are obtained with a resolution of 2 km in the horizontal direction and 1 km in depth. We used a total of 8589 P wave arrival times from 1014 local earthquakes recorded by both the Zipingpu reservoir network and temporary stations deployed in the area. The 3-D velocity images at shallow depth show the low-velocity regions have strong correlation with the surface trace of the Zipingpu reservoir. According to the extension of those low-velocity regions, the infiltration depth directly from the Zipingpu reservoir itself is limited to 3.5 km depth, while the infiltration depth downwards along the Beichuan-Yingxiu fault in the study area is about 5.5 km depth. Results show the low-velocity region in the east part of the study area is related to the Proterozoic sedimentary rocks. The Guanxian-Anxian fault is well delineated by obvious velocity contrast and may mark the border between the Tibetan Plateau in the west and the Sichuan basin in the east.

Download Full-text

Results of a seismic reflection survey across the fault zone between the Thompson nickel belt and the Churchill Tectonic Province, northern Manitoba

Canadian Journal of Earth Sciences ◽

10.1139/e81-002 ◽

1981 ◽

Vol 18 (1) ◽

pp. 13-25 ◽

Cited By ~ 5

Author(s):

A. G. Green

Keyword(s):

Fault Zone ◽

Lower Crust ◽

Seismic Reflection ◽

High Amplitude ◽

Small Scale ◽

Upper Crust ◽

Travel Times ◽

Reflection Point ◽

Point Data ◽

Amplitude Reflection

Approximately 11 km of four-fold common reflection point data have been recorded across a region that spans the contact fault zone between the Thompson nickel belt and the Churchill Tectonic Province. From these data it is shown that the upper crust in this region and, to a lesser extent, the lower crust are characterized by numerous scattered events that originate from relatively small-scale features. Within the Thompson nickel belt two extensive and particularly high-amplitude reflection zones, at two-way travel times of t = 5.0–5.5 s and t = 6.0–6.5 s, are recorded with apparent northwesterly dips of 0–20 °C. These reflection zones, which have a laminated character, are truncated close to the faulted contact with the Churchill Province. Both the contact fault zone and the Churchill Province in this region have crustal sections that are relatively devoid of significant reflectors. The evidence presented here confirms that the crustal section of the Thompson nickel belt is fundamentally different from that of the Churchill Tectonic Province.

Download Full-text

Distinct tectonic activities in Guangxi, China due to large earthquakes on the Longmenshan fault zone

Physics of The Earth and Planetary Interiors ◽

10.1016/j.pepi.2020.106557 ◽

2020 ◽

Vol 307 ◽

pp. 106557

Author(s):

Huaizhong Yu ◽

Jing Zhao ◽

Xiaoxia Liu ◽

Chen Yu ◽

Chong Yue ◽

...

Keyword(s):

Fault Zone ◽

Longmenshan Fault Zone ◽

Longmenshan Fault ◽

Large Earthquakes ◽

Tectonic Activities

Download Full-text

Seismic Potential Around the Northeastern Edge of the Longmenshan Fault Zone as Inferred from Seismological Observations

Pure and Applied Geophysics ◽

10.1007/s00024-019-02098-3 ◽

2019 ◽

Vol 177 (1) ◽

pp. 37-53 ◽

Cited By ~ 1

Author(s):

Reiken Matsushita ◽

Kazutoshi Imanishi ◽

Makiko Ohtani ◽

Yasuto Kuwahara ◽

Jiuhui Chen ◽

...

Keyword(s):

Fault Zone ◽

Longmenshan Fault Zone ◽

Seismic Potential ◽

Longmenshan Fault

Download Full-text

Research on Transverse Faults in the Longmenshan Fault Zone, China

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1010-1012.1380 ◽

2014 ◽

Vol 1010-1012 ◽

pp. 1380-1386

Author(s):

Wei Feng Wang ◽

Chuan Hua Zhu ◽

Yan Bin Qing ◽

Xin Jian Shan

Keyword(s):

Remote Sensing ◽

Fault Zone ◽

Field Studies ◽

Geophysical Data ◽

Remote Sensing Images ◽

Longmenshan Fault Zone ◽

Geomorphic Features ◽

Longmenshan Fault ◽

Regional Tectonic

The Longmenshan fault zone has been a research hotspot, but fewer scholars have paid attention to its transverse faults. According to the analysis of regional tectonic, seismic activities, geomorphic features, remote sensing images, and deep geophysical data, combined with field studies, the existence, distribution and type of the transverse faults in the Longmenshan fault zone were demonstrated. Research shows that there are 9 transverse faults that lie parallel to each other approximately at ~50km intervals in the Longmenshan fault zone. And transverse faults can be divided into regional transverse faults and localized transverse faults with NW strike, nearly EW strike and nearly SN strike.

Download Full-text