沂沭断裂带现代构造应力场与地震活动
RECENT TECTONIC STRESS FIELD AND SEISMICITY IN YIHE-SHUHE FAULT BELT
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摘要: 本文利用小震震源机制解及单台平滑机制解资料,研究了沂沭断裂带及其附近地区的应力场特征,结果表明:沂沭断裂带应力主轴P为72°,T为342°,与苏、鲁、皖、豫地区应力场取向一致;该带应力场存在纵向上的分段差异;不同深度的地震机制结果统计表明,震源较深的地震(h≥17公里)机制更能真实地反映地壳应力场。最后对该带近期地震活动的基本特征及其与活动断裂、受力状态和破裂角大小等因素的关系进行了初步分析。Abstract: In this paper, by use of focal mechanism solutions of 31 small shocks and 15 single stations(average result), the characteristics of stress fields of Yihe-Shuhe fault belt and its adjacent region are studied. The results have shown that the directions of principal stress axes, P and T, in Yihe-Shuhe fault belt are 72° and 342°, respectively, which agree with that in Jiangsud Shandong-Anhui-Henan region; the stress field difference at vertical variant segments in the fault belt is obvious. The statistical result of mechanism of earthquakes at different depth has shown that the focal mechanism of earth quakes in depth more than 17km appers to reflect crustal stress field more really. The mechanical model of Yihe-Shuhe fault belt is given. Finally, the recent characters of seismicity in this fault belt and its relation to active fault, stress state and fracture angle have been discussed.
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