We use five published source models to calculate the Coulomb failure stress changes induced by the Ms8.0 Wenchuan earthquake, and analyze the association between stress changes and the subsequent earthquakes. Based on...We use five published source models to calculate the Coulomb failure stress changes induced by the Ms8.0 Wenchuan earthquake, and analyze the association between stress changes and the subsequent earthquakes. Based on the analysis of uncertainties resulting from source models, we determine the stress changes on nearby faults caused by the Wenchuan earthquake. Moreover, we focus on the seismicity rate change as a function of time on every fault under the influence of stress changes. The results indicate that the spatial distributions of aftershocks correlate well with the regions where stress is calculated to increase using the related models. The largest lobes of dropped stress lie in the west and east sides of source fault. The largest lobes of increased failure stress close to southern and northern ends of the source fault extend into the whole source failure plane. In addition, another region of increased stress lies in the Wenchuan-Yingxiu zone close to the southern segment of source fault, where a large number of aftershocks have occurred. And subsequent earthquakes seem to extend to even more remote distances; therefore, this area also has a high risk of seismic hazard. We find that the positive stress changes on nearby faults imposed by the Wenchuan earthquake produce an encouraging effect on seismicity rate. The effect is most significant on the Pengxian-Guanxian fault and Qingchuan fault, the value of seismicity rate maintains two times greater than the value before the mainshock for the next hundred years on these faults, and the time needed for the aftershock rate to recover to the pre-mainshock seismicity rate can reach up to 800-900 yr. The influence is not significant on the western Qinling fault, the Longquanshan fault, the Xianshuihe fault, the Yulongxi fault, the Anninghe fault, the Minjiang fault, and the Aba fault. Compared with the seismicity rate on these faults before the mainshock, the aftershock rate is raised by less than two times, and the time of perturbation duration is not long. The s展开更多
In general, earthquake cycle related to earthquake faulting could include four major processes which could be described by （1） fault locking, （2） self-acceleration or nucleation （possible foreshocks）, （3） cose...In general, earthquake cycle related to earthquake faulting could include four major processes which could be described by （1） fault locking, （2） self-acceleration or nucleation （possible foreshocks）, （3） coseismic slip, and （4） post-stress relaxation and afterslip. A sudden static stress change/perturbation in the surrounding crust can advance/ delay the fault instability or failure time and modify earth- quake rates. Based on a simple one-dimensional spring-sli- der block model with the combination of rate-and-state- dependent friction relation, in this study, we have approxi- mately derived the simple analytical solutions of clock advance/delay of fault failures caused by a sudden static Coulomb stress change applied in the different temporal evolution periods during an earthquake faulting. The results have been used in the physics-based explanation of delayed characteristic earthquake in Parkfield region, California, in which the next characteristic earthquake of M 6.0 after 1966 occurred in 2004 instead of around 1988 according to its characteristic return period of 22 years. At the same time, the analytical solutions also indicate that the time advance/ delay in Coulomb stress change derived by the dislocation model has a certain limitation and fundamental flaw. Fur- thermore, we discussed the essential difference between rate- and state-variable constitutive （R-S） model and Coulomb stress model used commonly in current earthquake triggering study, and demonstrated that, in fact, the Coulomb stress model could be involved in the R-S model. The results, we have obtained in this study, could be used in the development of time-dependent fault interaction model and the probability calculation related to the time-dependent and renewal earthquake prediction model.展开更多
基金supported by National Natural Science Founda-tion of China (Grant No. 40364001)the Construction Project of Inte-grated Deep-Well Seismic Observation System in Shanghai
文摘We use five published source models to calculate the Coulomb failure stress changes induced by the Ms8.0 Wenchuan earthquake, and analyze the association between stress changes and the subsequent earthquakes. Based on the analysis of uncertainties resulting from source models, we determine the stress changes on nearby faults caused by the Wenchuan earthquake. Moreover, we focus on the seismicity rate change as a function of time on every fault under the influence of stress changes. The results indicate that the spatial distributions of aftershocks correlate well with the regions where stress is calculated to increase using the related models. The largest lobes of dropped stress lie in the west and east sides of source fault. The largest lobes of increased failure stress close to southern and northern ends of the source fault extend into the whole source failure plane. In addition, another region of increased stress lies in the Wenchuan-Yingxiu zone close to the southern segment of source fault, where a large number of aftershocks have occurred. And subsequent earthquakes seem to extend to even more remote distances; therefore, this area also has a high risk of seismic hazard. We find that the positive stress changes on nearby faults imposed by the Wenchuan earthquake produce an encouraging effect on seismicity rate. The effect is most significant on the Pengxian-Guanxian fault and Qingchuan fault, the value of seismicity rate maintains two times greater than the value before the mainshock for the next hundred years on these faults, and the time needed for the aftershock rate to recover to the pre-mainshock seismicity rate can reach up to 800-900 yr. The influence is not significant on the western Qinling fault, the Longquanshan fault, the Xianshuihe fault, the Yulongxi fault, the Anninghe fault, the Minjiang fault, and the Aba fault. Compared with the seismicity rate on these faults before the mainshock, the aftershock rate is raised by less than two times, and the time of perturbation duration is not long. The s
文摘In general, earthquake cycle related to earthquake faulting could include four major processes which could be described by （1） fault locking, （2） self-acceleration or nucleation （possible foreshocks）, （3） coseismic slip, and （4） post-stress relaxation and afterslip. A sudden static stress change/perturbation in the surrounding crust can advance/ delay the fault instability or failure time and modify earth- quake rates. Based on a simple one-dimensional spring-sli- der block model with the combination of rate-and-state- dependent friction relation, in this study, we have approxi- mately derived the simple analytical solutions of clock advance/delay of fault failures caused by a sudden static Coulomb stress change applied in the different temporal evolution periods during an earthquake faulting. The results have been used in the physics-based explanation of delayed characteristic earthquake in Parkfield region, California, in which the next characteristic earthquake of M 6.0 after 1966 occurred in 2004 instead of around 1988 according to its characteristic return period of 22 years. At the same time, the analytical solutions also indicate that the time advance/ delay in Coulomb stress change derived by the dislocation model has a certain limitation and fundamental flaw. Fur- thermore, we discussed the essential difference between rate- and state-variable constitutive （R-S） model and Coulomb stress model used commonly in current earthquake triggering study, and demonstrated that, in fact, the Coulomb stress model could be involved in the R-S model. The results, we have obtained in this study, could be used in the development of time-dependent fault interaction model and the probability calculation related to the time-dependent and renewal earthquake prediction model.
