摘要
利用速率-状态摩擦定律(Rate-and State-Dependent Friction Law:简称RSF定律),结合McKenzie-Brune摩擦生热模型,本文分别从Ruina提出的RSF定律和Chester-Higgs提出的RSF定律出发,通过一维弹簧-滑块模型,采用四阶变步长的Dormand-Prince算法,对断层演化过程进行了数值模拟,探讨了摩擦生热对断层演化进程的影响.模拟结果显示,与Ruina-模型相比,Chester-Higgs-模型在断层高速滑动时存有更大的摩擦强度,表明摩擦生热对断层具有一定的强化作用,且同临界滑移距离的取值相关.而且,Chester-Higgs-模型在失稳时的断层面温度远远低于Ruina-模型,表明摩擦生热在断层演化过程中能抑制断层面温度的剧烈升高,且正应力和临界滑移距离越大,两种模型的温差越为明显,而断层的刚度和尺度则对温度的影响很小.模拟两种模型周期演化过程的结果表明,在相同的初始条件下,Chester-Higgs-模型给出的断层失稳周期明显比Ruina-模型更短,说明摩擦生热对断层自身演化最显著的影响是较大地缩短了地震重复发生周期.当断层进入周期性演化后,Chester-Higgs-模型给出的摩擦强度大于Ruina-模型,且对第一次非周期性失稳的摩擦强度和剩余应力的继承性更好.另外,由ChesterHiggs-模型给出的静态应力降远小于Ruina-模型给出的结果,所对应的单个事件的滑移量也小于Ruina-模型.
With a combination of the Rate-and State-Dependent Friction Law(RSF law)and the McKenzie-Brune frictional heat generation model,in this paper we have studied the effects of frictional heating on the fault strength variation and temporal evolution of temperature based on the spring-slider-fault system governed by Ruina and Chester-Higgs RSF laws.The system of equations is solved by fourth-order Dormand-Prince algorithm with adaptive step-size control.With a comparison to the Ruina-model in which the temperature effect due to frictional heating on frictional strength is neglected,the numerical results show that the fault frictional strength will keep a little bit higher for the Chester-Higgs-model in which the temperature effect due to frictional heating on frictional strength is taken into consideration.The simulation results also indicate that,for the Chester-Higgs-model,although the frictional strength is strengthened by temperature rise due to frictional heating during the pre-seismic sliding,the temperature change is much smaller than that given by the Ruina-model.Relating to the increases of the critical distance of Dc,the fault instability times become longer accompanied by significant temperature increase for both models.However,when Dcreaches a certain value,the temperature on the fault almost keep the same value(constant)until the instability occurs.Moreover,the numerical simulation also indicates that,during the entire pre-seismic period,the temperature rise is almost independent on the spring stiffness and the absolute value of the temperature rise is much lower for the ChesterHiggs-model.In addition,we investigated the mechanics of fault stick-slip cycles with both models.Related to this,we observe highly regular stick-slip events with distinct temperature characteristics,and scaling relation between temperature T and slip period Tcycle.The simulated results suggest that,under the same initial conditions,the seismic occurrence time(quasi-periodic stick-slip)giving by the Chester-Higgs-model is obviously shorter than that by the Ruina-model,indicating that a significant effect of friction heating generated on entire fault temporal evolution is greatly shortening the seismic recurrence time.And the friction strength resultant from the Chester-Higgs-model is much higher than that from the Ruina-model.Correspondingly,both static stress drop and total slip resulted from the Chester-Higgs-model is also smaller than that from the Ruina-model,respectively.
作者
高雅琪
史保平
GAO YaQi;SHI BaoPing(College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第6期2297-2310,共14页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(41574040)资助.
