可可托海—二台断裂带现代位移特征研究

A Research on the Recent Displacement of the Kuktoukai-Ertai Fault Zone

布设在可可托海—二台断裂带上的三处三角测量观测场地和布设在额尔齐斯断裂带上的一处三角测量观测场地现已积累了四期资料。在对这些资料分析的基础上,本文提出了该断裂带的位移特征及构造应力特征。分析结果表明,断层除继承性活动外,在地震活跃时还表现为反向运动,就其断层平均位移量的绝对值而言,可可托海—二台断裂为7mm/年,在平行于断层方向的位错为4mm/年;额尔齐斯断裂的位移量为8mm/年,在平行于断层方向上的位错为5mm/年。应力分析结果表明,1984年以来剪应变主要集中于断层两端。北端近期地震活动较为频繁,应力在一定程度上得到释放;而南端的地震活动已沉寂八年之久,况且应力自1986年以来一直在集中。这一地区的发展动向,应引起同行注意。另外,可可托海—二台断裂带北端在向北发展,而南端却始终未能向南发展。

In the famous Kuktoukai-Ertai fault zone, three triangulation networks were installed and one was done in the Erqis fault. According to the analysis, we present the recent characteristics of both displacement and tectonic stress along the faults. Not only the faults have adoptive motion, but also they have reverse motion during seismic active period. The absolute value of the displacement in the Kuktoukai-Ertai fault is 7 mm/year and the component along the fault is 4 mm/year. The absolute value of the displacement in the Erqis fault is 8 mm/year and the component along the fault is 5 mm/year. By the analysis of the stress force,we can see the force mainly centred in both ends of the,fault since 1984. In the recent years,the earthquake took place more frequently in the north of the fault and the stress force was released too. But in the south,there is no earthquake since 1981 and the stress force was increased since 1986. We should pay attention to this area. In addition,the north end of the Kuktoukai-Ertai fault have been developing to north,but there is no such development in the south.