scholarly journals Subsurface structure and spatial segmentation of the Longmen Shan fault zone at the eastern margin of Tibetan Plateau: Evidence from focal mechanism solutions and stress field inversion

2019 ◽  
Vol 757 ◽  
pp. 10-23 ◽  
Author(s):  
Xianrui Li ◽  
Tobias Hergert ◽  
Andreas Henk ◽  
Dun Wang ◽  
Zuoxun Zeng
Keyword(s):  
Tibetan Plateau ◽  
Stress Field ◽  
Fault Zone ◽  
Focal Mechanism ◽  
Subsurface Structure ◽  
Focal Mechanism Solutions ◽  
Eastern Margin ◽  
Spatial Segmentation ◽  
Longmen Shan Fault ◽  
Field Inversion

Focal mechanism and stress field in the northeastern Tibetan Plateau: insight into layered crustal deformations

2019 ◽  
Vol 218 (3) ◽  
pp. 2066-2078 ◽  
Author(s):  
Cunrui Han ◽  
Zhouchuan Huang ◽  
Mingjie Xu ◽  
Liangshu Wang ◽  
Ning Mi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Stress Field ◽  
Focal Mechanism ◽  
Horizontal Stress ◽  
P Wave ◽  
The Tibetan Plateau ◽  
Linear Inversion ◽  
Focal Mechanism Solutions ◽  
Stress Orientations ◽  
Ne Tibetan Plateau

SUMMARY Focal mechanism solutions (FMSs) reflect the stress field underground directly. They provide essential clue for crustal deformations and therefore improve our understanding of tectonic uplift and expansion of the Tibetan Plateau. In this study, we applied generalized Cut and Paste and P-wave first-motion methods to determine 334 FMSs (2.0 ≤ Mw ≤ 6.4) with the data recorded by a new temporary network deployed in the NE Tibetan Plateau by ChinArray project. We then used 1015 FMSs (including 681 published FMSs) to calculate the regional stress field with a damped linear inversion. The results suggest dominant thrust and strike-slip faulting environments in the NE Tibetan Plateau. From the Qilian thrust belt to the Qinling orogen, the maximum horizontal stress orientations (${S_\mathrm{ H}}$) rotate clockwise from NNE to NE, and further to EW, showing a fan-shaped pattern. The derived minimum horizontal stress orientations (${S_\mathrm{ h}}$) are parallel to the aligned fabrics in the mantle lithosphere indicated by shear wave splitting measurements, suggesting vertically coherent deformation in the NE Tibetan Plateau. Beneath the SW Qinling adjacent to the plateau, however, the stress orientations in the shallow and deep crust are different, whereas the deep crustal stress field indicates possible ductile crustal flow or shear.

Characteristics and implications of the stress state in the Longmen Shan fault zone, eastern margin of the Tibetan Plateau

2015 ◽  
Vol 656 ◽  
pp. 1-19 ◽  
Author(s):  
Wen Meng ◽  
Qunce Chen ◽  
Zhen Zhao ◽  
Manlu Wu ◽  
Xianghui Qin ◽  
...  
Keyword(s):  
Stress State ◽  
Tibetan Plateau ◽  
Fault Zone ◽  
The Tibetan Plateau ◽  
Eastern Margin ◽  
Longmen Shan Fault

scholarly journals ESR geochronology of the Minjiang River terraces at Wenchuan, eastern margin of Tibetan Plateau, China

2013 ◽  
Vol 40 (4) ◽  
pp. 360-367 ◽  
Author(s):  
Chun-Ru Liu ◽  
Gong-Ming Yin ◽  
Hui-Ping Zhang ◽  
Wen-Jun Zheng ◽  
Pierre Voinchet ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tectonic Activity ◽  
The Tibetan Plateau ◽  
Fluvial Sediments ◽  
River Terrace ◽  
Eastern Margin ◽  
River Terraces ◽  
Quaternary Climate ◽  
Minjiang River ◽  
Longmen Shan Fault

Abstract The Minjiang River terrace along the Longmen Shan fault zone near Wenchuan, at the eastern margin of the Tibetan Plateau, China, provides archives for tectonic activity and quaternary climate change. However, previous studies were not able to provide ages older than 100 ka due to the limitations of dating material or/and methods applied to date the fluvial sediments. In this study, we used the ESR signal of the Ti-Li center in quartz to obtain the ages of four higher terraces (T3–T6). According to the results, the terraces T3 to T6 were formed at 64±19 ka, 101±15 ka, 153±33 ka, and 423±115 ka, respectively. Combined with previous studies, these results indicate that the formations of all terraces correspond to glacial/interglacial transition periods, such as, T1-T5 being correlated to MIS2/1, MIS4/3, MIS5d/5c, and MIS6/5e respectively, while T6 probably to MIS12/11. According to these data, it is found that the average incision rate was significantly higher over the last 150 ka than that previous 100 ka (250 to 150 ka). As both tectonics and climate have affected the formation of these terraces, in addition to the overall uplifting of Tibetan Plateau, the regional uplift due to isostasy would be an additional tectonic factor in the formation of river terraces in the eastern margin of Tibetan plateau.

Evidence for normal and deep-buried features of the Longquan Shan fault zone at the eastern margin of the Tibetan plateau

2019 ◽  
Vol 179 ◽  
pp. 56-64 ◽  
Author(s):  
Guangyu Fu ◽  
Xiaoning Su ◽  
Yawen She ◽  
Tai Liu ◽  
Jun Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Fault Zone ◽  
The Tibetan Plateau ◽  
Eastern Margin

scholarly journals Focal mechanisms and the stress field in the aftershock area of the 2018 Hokkaido Eastern Iburi earthquake (MJMA = 6.7)

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Yuki Susukida ◽  
◽  
Kei Katsumata ◽  
Masayoshi Ichiyanagi ◽  
Mako Ohzono ◽  
...  
Keyword(s):  
Stress Field ◽  
Principal Stress ◽  
Focal Mechanism ◽  
P Wave ◽  
Japan Meteorological Agency ◽  
Inversion Method ◽  
Reverse Fault ◽  
Focal Mechanism Solutions ◽  
Fault Type ◽  
Aftershock Area

AbstractThe tectonic stress field was investigated in and around the aftershock area of the Hokkaido Eastern Iburi earthquake (MJMA = 6.7) occurred on 6 September 2018. We deployed 26 temporary seismic stations in the aftershock area for approximately 2 months and located 1785 aftershocks precisely. Among these aftershocks, 894 focal mechanism solutions were determined using the first-motion polarity of P wave from the temporary observation and the permanent seismic networks of Hokkaido University, Japan Meteorological Agency (JMA), and High Sensitivity Seismograph Network Japan (Hi-net). We found that (1) the reverse faulting and the strike-slip faulting are dominant in the aftershock area, (2) the average trend of P- and T-axes is 78° ± 33° and 352° ± 51°, respectively, and (3) the average plunge of P- and T-axes is 25° ± 16° and 44° ± 20°, respectively: the P-axis is close to be horizontal and the T-axis is more vertical than the average of the P-axes. We applied a stress inversion method to the focal mechanism solutions to estimate a stress field in the aftershock area. As a result, we found that the reverse fault type stress field is dominant in the aftershock area. An axis of the maximum principal stress (σ1) has the trend of 72° ± 7° and the dipping eastward of 19° ± 4° and an axis of the intermediate principal stress (σ2) has the trend of 131° ± 73° and the dipping southward of 10° ± 9°, indicating that both of σ1- and σ2-axes are close to be horizontal. An axis of the minimum principal stress (σ3) has the dipping westward of 67° ± 6° that is close to be vertical. The results strongly suggest that the reverse-fault-type stress field is predominant as an average over the aftershock area which is in the western boundary of the Hidaka Collision Zone. The average of the stress ratio R = (σ1 − σ2)/(σ1 − σ3) is 0.61 ± 0.13 in the whole aftershock area. Although not statistically significant, we suggest that R decreases systematically as the depth is getting deep, which is modeled by a quadratic polynomial of depth.

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