张北6.2级地震前后断层活动时空演化特征分析

TEMPORAL AND SPATIAL EVOLUTION CHARACTERISTICS OF FAULT ACTIVITY BEFORE AND AFTER ZHANGBEI Ms6.2 EARTHQUAKE

利用首都圈地区的24处跨断层流动水准观测资料,计算了断层垂直形变速率,运用主成分分析方法对研究区断层垂直形变速率进行了合成,从时空角度分析了张北地震前后跨断层形变异常特征。结果表明,张北地震前首都圈地区的部分跨断层水准测点出现了一定的异常变化。时间上,观测曲线大致从1994年开始出现准同步的加速、转折,恢复到原来水平后发震;空间上,地震前2～3年研究区整体由张性转为压性,最后逐渐形成了以震中区为压性区而远离震中的地区压性逐渐减弱的空间分布格局。张北地震后,研究区出现了大范围的张性区,并且处于相对稳定的空间分布状态,这可能与区域应力的充分释放有关。

We analyzed 24 observational data of temporary fault-crossing leveling measurement in the Capital region of China and calculated the vertical fault deformation rate. With the principal component analysis method, we made a rate synthesizing from the vertical fault displacement rate in the study area, and then carried out a deep a- nalysis of the deformation anomaly characteristics before and after the Zhangbei earthquake in the view from space and time. The results show that the part of stations in the Capital Region had some certain anomalies before the Zhangbei earthquake. In the view from time, the observation curves generally began to appear acceleration or turn- ing simultaneously from 1994, the earthquake broke out after restoring to its original level, or exception to the maxi- mum. From the point of space, 2 to 3 years before the earthquake the studied area as a whole converted to pressure from the tensile, and gradually formed a pressure zone around the epicenter area and the pressure gradually decreased in the area far from the epicenter. After the Zhangbei earthquake, the studied area emerged a wide range of tensile in a relatively stable spatial distribution, which may be related to the full release of the stress.