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Estimation of friction parameters on plate boundaries

板块边界摩擦参数的估计

基本信息

批准号：
17540394
负责人：
KATO Naoyuki
金额：
$ 1.98万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

(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

(1)抗震滑动与地震相互作用的数值模拟。我们使用实验室推导的速率和状态相关摩擦定律对板块界面上的滑动行为进行数值模拟，以了解抗震滑动对地震发生的影响。考虑到大粗糙体的复发破裂，假设速度减弱摩擦，我们模拟了在粗糙体周围的速度增强区域中缓慢向外传播的震后滑动。从模拟中，我们发现传播震后滑动的特性，例如传播速度，取决于摩擦参数，并且传播震后滑动可能会在小凹凸处引发破裂，导致余震区域随时间的扩展。结果表明，根据大地测量数据观察震后滑动的时空演化以及与时间相关的余震区域可能有助于估计摩擦参数。此外，模拟表明，由于摩擦特性的时间和速率依赖性，大粗糙体破裂引起的滑动速度扰动会显着影响小粗糙体的破裂特性。在根据小重复地震的重现模式估计滑动速度时必须考虑到这种效应。 (2)大地测量和地震数据分析。根据 GPS 数据估算了东海地震假设震源区下方板块界面上地震滑动的时空演化。我们得到了剪切应力和滑移之间以及剪切应力和滑移速率之间的关系，并根据这些关系估计了弱速摩擦特性。这与基于速率和状态相关摩擦的慢地震模型是一致的。通过对小重复地震的分析，估计了日本东北部日本海沟板块界面上地震滑动的时空演化。为了根据小重复地震的数据估计滑动速度，需要同震滑动与震级之间的关系。小重复地震的经验关系与应力降恒定的通常地震所使用的经验关系显着不同。在粗糙体断裂力学的基础上，得到了小重复地震经验标度关系的理论解释。较少的