Estimation of friction parameters on plate boundaries

(1)地震与非地震滑动相互作用的数值模拟。我们进行了数值模拟板界面上的滑动行为，使用实验室得出的速率和状态相关的摩擦定律，以了解地震发生的抗震滑动的影响。考虑复发破裂的一个大的粗糙，其中速度减弱摩擦假设，我们模拟震后滑动缓慢向外传播的速度加强区周围的粗糙。从模拟结果中我们发现，地震后滑动的传播特性，如传播速度，取决于摩擦参数，地震后滑动的传播可能会触发破裂的小凸起，造成余震区的时间依赖性扩大。结果表明，利用大地测量资料对震后滑动的时空演化和余震面积随时间变化的观测，对摩擦参数的估计是有用的。进一步 ...更多信息 模拟结果表明，由于摩擦特性的时间和速率依赖性，大微凸体破裂引起的滑动速度扰动显著影响小微凸体的破裂特性。在利用小震重复图象估算滑动速度时，必须考虑这种影响。(2)分析大地测量和地震数据。利用GPS资料估算了东海地震假定震源区下方板块界面上的滑动时空演化。得到了剪切应力与滑移、滑移率之间的关系，并根据该关系对减速摩擦特性进行了估计。这与基于速率和状态相关摩擦的慢地震模型是一致的。通过对日本东北部小震重复的分析，估计了沿日本海沟沿着板块界面上地震滑动的时空演化。为了从小重复地震的资料中估算滑动速度，需要同震滑动与震级之间的关系。重复小震的经验关系式与常震应力降为常数的经验关系式有很大不同。根据粗糙体的断裂力学，对小震重复的经验标度关系给出了理论解释。少

(1) Numerical simulation about interaction between aseismic sliding and earthquakes. We performed numerical simulations of sliding behavior on plate interfaces using laboratory-derived rate- and state-dependent friction laws to understand the effects of aseismic sliding on earthquake occurrence. Considering recurrence rupture of a large asperity, where velocity-weakening friction was assumed, we modeled postseismic sliding propagating slowly outward in velocity-strengthening region around the asperity. From the simulations, we found the property of propagating postseismic sliding, such as the propagation speed, depends on friction parameters, and the propagating postseismic sliding may trigger rupture at small asperities, causing time dependent expansion of aftershock areas. The results indicate that the observations about space-time evolution of postseismic sliding from geodetic data and about time dependent aftershock areas may be useful for estimating friction parameters. Furthermor … More e, the simulations indicate that perturbation in sliding velocity due to rupture of a large asperity significantly affects the characteristics of rupture of small asperities because of time and rate dependence of frictional characteristics. This effect must be taken into consideration in estimating sliding velocity from recurrence pattern of small repeating earthquakes. (2) Analysis of geodetic and seismic data. The spatio-temporal evolution of aseismic sliding on the plate interface below the hypothetical source area of the Tokai earthquake was estimated from GPS data. We obtained the relations between shear stress and slip and between shear stress and slip rate, and velocity-weakening frictional property was estimated from the relations. This is consistent with a model for slow earthquakes on the basis of the rate- and state-dependent friction. The spatio-temporal evolution of aseismic sliding on the plate interface along the Japan trench, northeastern Japan, was estimated from the analysis of small repeating earthquakes. In order to estimate sliding velocities from the data of small repeating earthquakes, the relation between coseismic slip and magnitude is required. The empirical relation for small repeating earthquake is significantly different from that has been used for usual earthquakes, in which stress drop is constant. On the basis of fracture mechanics of an asperity, a theoretical explanation for the empirical scaling relation for the small repeating earthquakes was obtained. Less