1995年7月河北沙城地震群的震源断层

利用在怀来附近布设的中－欧合作小孔径数字化地震台网的资料，以相对定位法测定了１９９５年７月河北沙城地震群５４个地震的震源机制。从三维空间上分析了沙城震群的震源位置，震源机制，认为震源断层是ＮＥ向高倾角右旋走滑断层，并将其与宏观调查结果，地质活断层等作了对比。研究后认为：沙城震群发生在地壳浅层ＮＥ向地质断层延伸和扩展的新破裂上，属于现代地壳应力场作用下浅层断层延伸和扩展的新破裂上，属于现代地壳应力场

Source Fault of Shacheng Earthquake Swarm Occurred in July 1995, Hebei Province

Based on the data obtained from the small\|aperture digital seismogragh network which was collaborated by China and Europe and deployed in the vicinity of Huailai,the focal locations of Shacheng earthquake swarm occurred in July 1995 in Hebei Province which have been determined by the relative locating method.The maximum amplitude ratio of P to S wave has been fitted by the calculated seismogram and the focal mechanism of 54 shocks of this swarm has been inverted.3\|dimensional analysis of the focal locations and mechanism of Shacheng earthquake swarm shows that the source fault is a NE striking right\|lateral slip fault with high dip.We also compared the source fault with the results from macroscopic investigation and the geological active fault.Shacheng earthquake swarm is regarded to occur on the new rupture in the extension of the NE geological fault in the shallow crust,which can be considered that the earthquakes occurred in the development process of shallow fault under the action of modern crustal stress field.The significance of the method proposed by the authors to analyze source fault by using the data of focal distribution and mechanism of an earthquake sequence has been discussed.