濮阳小震集中区发震机理分析与讨论

Analyses and discussion on mechanism of clustered microearthquakes in Puyang, Henan Province

综合小震精定位和震源机制解两方面的结果,对濮阳小震集中区小震丛集活动的发震机理进行了分析。双差定位结果显示,大部分地震震源位于聊考主干断裂上,与断层的产状吻合;5次ML≥3.5地震的震源机制显示,双力偶模型可以较好地解释观测波形,小震震源机制主要为走滑型,初动符号呈象限分布;在参考了油田地质构造背景资料后,对濮阳小震集中区中、小地震活动与油田采油作业之间是否存在注水诱发关系进行了讨论。

Based on microearthquakes fine relocations and focal mechanisms, the paper analyses the causes of clustered microseismicity in Puyang, Henan. The relocated results given by hypoDD shows that the hypocenters of most microearthquakes are situated at the trunk fault of Liaocheng- Lankao fault zone, and its distributions accord with the fault＇s attitude. Focal mechanisms of 5 events with ML l≥ 3.5 show that observed waveforms can be well explained by the double couple model. There are mainly strike-slip mechanisms in smaller events, with quadrantal polarities. On the basis of relative materials on geology and tectonic backgrounds of oilfield, the paper discusses inductive relationship between fluid injection for oil-production and microseismicity in this area.