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Synthetic Seismicity Model for the Xianshuihe Fault, Southwestern China

西南鲜水河断裂带综合地震活动模型

基本信息

批准号：
14340128
负责人：
KATO Naoyuki
金额：
$ 4.61万
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 (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340128/
关键词：
Xianshuihe fault GPS slip rate friction rock mechanics simulation seismicity

项目摘要

(1)Tectonic Model. We investigated deformation pattern of China using GPS data. Assuming that China consists of several rigid blocks, we determined displacement rates, slip deficit on faults, and internal deformation of the blocks. The results show that the displacement rate of the Sichuan-Yunnan block, which is caused by the collision of India, is 7.0 to 9.5 mm/yr, consistent with the geologically estimated value of 9 mm/yr. The slip deficit along the Xianshuihe fault is significantly smaller than the relative displacement rate between the two rigid blocks, indicating that the fault is virtually locked. (2)Laboratory Experiment. We measured acoustic emission (AE) during brittle deformation process of rock samples with preexisting joints under tri-axial compression. For rock samples without joints, the hypocenters of AEs are scattered and the fractal dimension of the hypocenter distribution is low when the applied compressional stress is low. On the other, in the case of rock samples w … More ith joints, AEs are concentrated along the joints under low compressional stress. AE clusters are generated near joint bends. (3)Numerical Simulation of Seismicity along the Xianshuihe Fault. We develop a synthetic seismicity model, assuming that the frictional stress of the fault follows a laboratory-derived rate and state-dependent friction law and using the long-term average slip rate along the fault estimated from geologically and geodetic observations. By selecting appropriate model parameters, we can simulate recurrence of active periods of fault motion with a recurrence interval of a few hundred years, being consistent with historically recorded seismicity. Rupture is arrested at regions of fault bend or branch or regions with velocity-strengthening frictional property. The arrested rupture is often reactivated after several years. This is because aseismic sliding propagates slowly in the velocity-strengthening regions. This explains migration of seismic activity along the fault. Less

(1)构造模型。利用GPS数据对中国大陆的形变模式进行了研究。假设中国由几个刚性块体组成，我们确定了位移率、断层滑动亏缺和块体内部变形。结果表明，受印度板块碰撞影响的川滇地块位移速率为7.0 ~ 9.5 mm/yr，与地质预测值9 mm/yr一致。鲜水河断裂带的滑动亏缺量明显小于两个刚性块体之间的相对位移速率，表明该断裂带实际上处于锁断状态。(2)实验室实验。在三轴压缩条件下，测量了含节理岩石试样脆性变形过程中的声发射。对于无节理的岩样，当施加压应力较小时，ae震源分散，震源分布的分形维数较低。另一方面，在节理较多的岩石样品中，ae在低压应力下沿节理方向集中。声发射簇在关节弯曲处附近产生。(3)鲜水河断裂带地震活动性数值模拟。我们开发了一个合成地震活动性模型，假设断层的摩擦应力遵循实验室推导的速率和状态相关的摩擦定律，并使用从地质和大地测量观测估计的沿断层的长期平均滑动速率。通过选择合适的模型参数，我们可以模拟出断层运动活跃期的重现，重现间隔为几百年，与历史记录的地震活动性相一致。断裂在断层弯曲或分支区域或具有速度强化摩擦特性的区域被阻止。被抑制的破裂常常在几年后重新激活。这是因为地震滑动在速度增强区域传播缓慢。这解释了地震活动沿断层的迁移。少