【摘要】 研究了1904年以来发生在中国四川、云南地区的强烈地震所伴生的库仑应力变化.研究区涉及了中国大陆最活动的地震带.由于欧亚板块与印度板块沿喜马拉雅会聚带的碰撞,菱形区域的构造运动受到西藏高原向东扩展的影响,在东—西方向上受到主要板内走滑断裂运动的调节.在研究区,断层顺时针逐步旋转,转动角达90°,造成了应力场的复杂性.计算了由强地震(MS≥6.5)的同震滑动和连续构造加载在主要断裂上产生的库仑破裂函数变化(ΔCFF).在应力评估模型的每一步,对是否能触发下一次地震的可能性都进行了判断.最后,模型给出了下一次地震中断层易于破裂的证据,对未来危险性进行了评估.更多还原

【Abstract】 Coulomb stress changes associated with the strong earthquakes occurred since 1904 in Sichuan and Yunnan Provinces of China are investigated.The study area comprises the most active seismic fault zones in the mainland of China and suffers from both strong and frequent events.The tectonic regime of this rhombic-shaped area is affected by the eastern extrusion of the Tibetan plateau due to the collision of Indian against the Eurasia lithospheric block along the Himalayan Convergent Zone.This movement is accommodated on major strike slip intraplate fault zones that strike in an E--W direction.The gradual 90° clockwise rotation of the faults in the study area contributes to the complexity of the stress field.The seismic hazard assessment in this region is attempted by calculating the change of the Coulomb failure function(ΔCFF)arising from both the coseismic slip of strong events(MS≥6.5)and the stress built-up by continuous tectonic loading on major regional faults.At every step of the stress evolutionary model an examination of possible triggering of each next strong event is made and the model finally puts in evidence the fault segments that apt to fail in an impending strong event,thus providing future seismic hazard evaluation.更多还原