断裂滑动速度对强震发生周期的影响——以东昆仑活动断裂带库赛湖断裂分段和西大滩断裂分段为例

The effect of fault slide velocity on the strong earthquake recurrence:A case study on Kusaihu and Xidatan segment of east Kunlun fault zone

2001年11月14日东昆仑断裂带库赛湖段发生8.1级大地震.事实上,库赛湖断裂分段大震的复发周期会受到其他分段运动行为的影响,尤其是临近的西大滩断裂分段.本文采用速度和状态依赖摩擦本构控制的一维弹簧滑块模型(BK模型)研究断裂分段滑动速度对强震复发周期的影响.以东昆仑活动断裂带库赛湖断裂分段和西大滩断裂分段作为实例进行研究,研究中将两断裂分段视为通过弹簧相连的滑块系统,其中模型参数的选择是以现有东昆仑活动断裂带库赛湖和西大滩分段的地质研究成果、历史地震和古地震资料直接给出,部分参数也采用了数值计算的方法.研究预测了两分段不同滑动速度对强震复发周期、断裂滑动速度及错动位移在未来0.5～0.6万年中随时间变化的影响.研究发现:在断裂分段之间的相互影响下,各断裂分段滑动速度与各段的强震发生周期没有规律性的关系;两断裂分段组成的系统中,某断裂分段滑动速度放慢(加快)会使该断裂分段未来强震发生的震级增大(减小),而对另外断裂分段的强震发生震级没有规律性影响;两断裂分段组成的系统中,某断裂分段滑动速度加快(放慢)会使另外的断裂分段在强震发生时错动的速度加快(放慢);同时,两断裂分段组成的系统中,某一断裂分段滑动速度上的变化对另一断裂分段强震复发周期的影响只有在较长时间跨度上才能体现.

On 14 November 2001, a strong earthquake of M8. 0 occurred in the Kusai lake fault segment of East Kunlun fault. In fact, the strong earthquake recurrence period of Kusai lake fault segment is affected by the slip motion of other segment near Kusai lake segment, especially the Xidatan fault segment. This study, we will apply the one-dimensional spring-block model controlled by the velocity and state frictional constitutive to research effect of different fault slip motion on the strong earthquake recurrence period. As an example, we research the Kusai Lake and Xidatan fault segment of East Kunlun fault. In the study, two fault segments can be thought as a system composed by two blocks connecting through a spring. The computation parameters of spring-block model of Kusaihu and Xidatan fault segment of Kulun fault zone are determined from the present geological research achievements on