The Garzê–Yushu strike-slip fault in central Tibet is the locus of strong earthquakes（M 〉 7）. The deformation and geometry of the co-seismic surface ruptures are reflected in the surface morphology of the fau...The Garzê–Yushu strike-slip fault in central Tibet is the locus of strong earthquakes（M 〉 7）. The deformation and geometry of the co-seismic surface ruptures are reflected in the surface morphology of the fault and depend on the structure of the upper crust as well as the pre-existing tectonics. Therefore, the most recent co-seismic surface ruptures along the Garzê–Yushu fault zone（Dangjiang segment） reveal the surface deformation of the central Tibetan Plateau. Remote sensing images and field investigations suggest a 85 km long surface rupture zone（striking NW-NWW）, less than 50 m wide, defined by discontinuous fault scarps, right-stepping en echelon tensional cracks and left-stepping mole tracks that point to a left-lateral strike-slip fault. The gullies that cross fault scarps record systematic left-lateral offsets of 1.8 m to 5.0 m owing to the most recent earthquake, with moment magnitude of about M 7.5, in the Dangjiang segment. Geological and geomorphological features suggest that the spatial distribution of the 1738 co-seismic surface rupture zone was controlled by the pre-existing active Garzê–Yushu fault zone（Dangjiang segment）. We confirm that the Garzê–Yushu fault zone, a boundary between the Bayan Har Block to the north and the Qiangtang Block to the south, accommodates the eastward extrusion of the Tibetan Plateau and generates strong earthquakes that release the strain energy owing to the relative motion between the Bayan Har and Qiangtang Blocks.展开更多
Yushu Ms7.1 earthquake occurred on the Ganzi-Yushu fault zone, across which we carried out a joint relative-gravity and seismic-reflection survey, and then performed a gravity inversion constrained by the seismic-refl...Yushu Ms7.1 earthquake occurred on the Ganzi-Yushu fault zone, across which we carried out a joint relative-gravity and seismic-reflection survey, and then performed a gravity inversion constrained by the seismic-reflection result. Based on the data of complete Bouguer gravity anomaly and seismic reflection, we obtained a layered interface structure in deep crust down to Moho. Our study showed that the inversion could reveal the interfaces of strata along the survey profile and the directions of regional faults in two-dimension. From the characteristics of the observed topography of the Moho basement, we tentatively confirmed that the uplift of eastern edge of Qinghai-Tibet plateau was caused by the subduetion of the Indian plate.展开更多
基金supported by the China Earthquake Administration Research Fund(Grant No.DZJ2016-18)the National Natural Science Foundation of China(Grant No.41602222)
文摘The Garzê–Yushu strike-slip fault in central Tibet is the locus of strong earthquakes（M 〉 7）. The deformation and geometry of the co-seismic surface ruptures are reflected in the surface morphology of the fault and depend on the structure of the upper crust as well as the pre-existing tectonics. Therefore, the most recent co-seismic surface ruptures along the Garzê–Yushu fault zone（Dangjiang segment） reveal the surface deformation of the central Tibetan Plateau. Remote sensing images and field investigations suggest a 85 km long surface rupture zone（striking NW-NWW）, less than 50 m wide, defined by discontinuous fault scarps, right-stepping en echelon tensional cracks and left-stepping mole tracks that point to a left-lateral strike-slip fault. The gullies that cross fault scarps record systematic left-lateral offsets of 1.8 m to 5.0 m owing to the most recent earthquake, with moment magnitude of about M 7.5, in the Dangjiang segment. Geological and geomorphological features suggest that the spatial distribution of the 1738 co-seismic surface rupture zone was controlled by the pre-existing active Garzê–Yushu fault zone（Dangjiang segment）. We confirm that the Garzê–Yushu fault zone, a boundary between the Bayan Har Block to the north and the Qiangtang Block to the south, accommodates the eastward extrusion of the Tibetan Plateau and generates strong earthquakes that release the strain energy owing to the relative motion between the Bayan Har and Qiangtang Blocks.
基金supported by the Key Foundation of Institute of Seismology,China Earthquake Administration( IS200916004)
文摘Yushu Ms7.1 earthquake occurred on the Ganzi-Yushu fault zone, across which we carried out a joint relative-gravity and seismic-reflection survey, and then performed a gravity inversion constrained by the seismic-reflection result. Based on the data of complete Bouguer gravity anomaly and seismic reflection, we obtained a layered interface structure in deep crust down to Moho. Our study showed that the inversion could reveal the interfaces of strata along the survey profile and the directions of regional faults in two-dimension. From the characteristics of the observed topography of the Moho basement, we tentatively confirmed that the uplift of eastern edge of Qinghai-Tibet plateau was caused by the subduetion of the Indian plate.
