Tectonophysics ( IF 2.9 ) Pub Date : 2021-10-13 , DOI: 10.1016/j.tecto.2021.229109 Xianrui Li 1, 2 , Tobias Hergert 1 , Andreas Henk 1 , Zuoxun Zeng 2
The slip rates on the faults in the eastern Tibetan Plateau play an important role in understanding the plateau's evolution and assessing its seismic hazard. In order to obtain a quantitative picture of the continuous slip rate along and slip partitioning between the faults, we establish a comprehensive 3D geomechanical-numerical model of the eastern Tibetan Plateau. Our results show that the NW-SE-trending faults usually slip faster than the faults striking in NE-SW direction. A substantial variation of the slip rate gradient along the Xianshuihe fault is revealed. The southeastern segment (Moxi fault) has a higher slip rate gradient than the northwestern segment, which is inferred to be caused by a clockwise rotation of the strike of the Xianshuihe fault from NW-SE to NNW-SSE near Kangding. This rotation combined with the accommodated southeastward movement of the Chuan-Dian Block further promotes normal faulting on the southwestern-most section of the Longmen Shan fault. According to the relatively higher slip rate of the Huya fault and the geometric distortion of the Yingxiu-Beichuan fault, we suggest that the Huya fault may have penetrated into the Longmen Shan fault zone and partially transmitted deformation of the Minshan Uplift into the sedimentary cover of the Sichuan basin. Based on the analysis of contemporary kinematics in the eastern Tibetan Plateau, we suggest that the Moxi fault has a high seismic hazard with the potential of an Ms7.4 earthquake, while the northeastern segment and the southwestern-most section of the Longmen Shan fault zone tend to produce more frequent but lower magnitude earthquakes.
中文翻译:
青藏高原东部的当代运动学:3D地质力学建模的见解
青藏高原东部断层的滑动速率对理解高原演化和评估其地震危险性具有重要作用。为了获得断层间连续滑动速率和滑动划分的定量图像,我们建立了青藏高原东部的综合 3D 地质力学-数值模型。我们的结果表明,NW-SE 向的断层通常比沿 NE-SW 方向的断层滑动得更快。揭示了沿鲜水河断裂滑动速率梯度的显着变化。东南段(磨溪断裂)滑移速率梯度大于西北段,推测是鲜水河断裂走向在康定附近由NW-SE向NNW-SSE顺时针旋转所致。这种旋转结合川滇地块的适应的东南运动进一步促进了龙门山断裂最西南段的正断层作用。根据虎牙断裂相对较高的滑动速率和映秀-北川断裂的几何畸变,我们认为虎牙断裂可能已经侵入龙门山断裂带,并将岷山隆起的变形部分传递到沉积盖层中。四川盆地。通过对青藏高原东部现代运动学的分析,我们认为磨溪断裂具有较高的地震危险性,有可能发生 7.4 级地震,而龙门山断裂带的东北段和最西南段为往往会产生更频繁但震级较低的地震。