【摘要】 根据历史地震记载、近期地震活动性和构造应力场资料，分析了北京西北延庆－怀来盆地的潜在地震危险性。指出自１９９５年７月２０日至１９９６年７月３０日发生于延庆－怀来盆地的ＭＬ＝４１地震序列的震源分布，揭示了分布于延庆－怀来盆地的两条共轭断层，位于这两条共轭断层延长线交汇处的怀来县城地区具有断层闭锁区的特征，该闭锁区域的线性尺度与一个６０级地震震源区的线性尺度相当，但延庆－怀来盆地近期微震活动未显示出该闭锁区在近期内将发生中强地震的征兆。对ＭＬ＝４１地震序列引起的地面运动的研究表明，该地震序列的震源谱可以用ω２模型表示，并且延庆－怀来盆地的品质因子ＱＳＨ值非常低，介于１４０与３６０之间，特别是在近震源地区ＱＳＨ值最低，只有１４０。更多还原

【Abstract】 The potential seismic risk in the Yangqing-Hualai basin,NW of Beijing City,is estimated using historical documents and recent seismicity and tectonic stress field data.It is found that the Huailai County area which is located at the intersection of two conjugate faults revealed by the activity of the M L=4 4 earthquake sequence in the period of July 20,1995 to June 30,1996, is of the characteristics for locked portion of a fault.The length of the locked portion is equivalent to a magnitude 6 0 earthquake.It is also found that recent activity of micro-earthquake in the basin does not appear visible anomaly related to the forthcoming of a major earthquake in short-term sense.Studies on the seismic ground motion indicate that the source spectrum can be described by a simple ω-squared model and that the Q SH in Yanqing- Huailai basin are very low( Q SH =140～360) and that in the near-source region the Q SH is the lowest.更多还原