龙门山断裂带上“破裂空段”的发震概率研究

Earthquake probability of the “seismic gap” on the Longmenshan fault

本文采用分层粘弹性介质模型计算了汶川地震对芦山震中产生的库仑应力加载的影响,进而结合Dieterich(1994)提出的速率状态摩擦定律给出芦山附近区域6级地震累积发震概率随时间的变化。结果显示,2013年芦山7.0级地震时其累积发震概率达18%,说明汶川地震产生的应力扰动加速了芦山地震的发生。本文还计算了汶川、芦山2次地震对其间"破裂空段"处产生的累积库仑应力扰动的影响,结合背景地震发生率,给出了"破裂空段"处6级地震累积发震概率变化。虽然计算结果可能受到大邑地震、介质模型参数的选取和背景地震发生概率等因素影响而存在一定误差,但"破裂空段"在2次强震应力加载下累积发震概率是不断增大的,因此我们认为"破裂空段"处发生中强地震的紧迫性不断增强。

Using the layered viscoelastic medium model, this paper calculates the Coulomb stress earthquake of Lushan region in 2013 is 18% ,indicating that the stress disturbance caused by the Wenchuan earthquake accelerated the Lushan earthquake. This paper also calculates the Coulomb stress accumulation on the ＂ seismic gap＂ generated by the Wenchuan, Lushan earthquakes, and gives the Mw 〉 6.0 earthquake probability of ＂ seismic gap＂ on the basis of the background seismicity. Although there may be a certain error in the results because of the Dayi earthquake, selection of the medium model parameters and background seismicity, the seismic probability of ＂seismic gap＂ is increasing and we believe that destructive earthquakes are still likely to occur in the ＂seismic gap＂.