【摘要】 1988年我们曾三次对位于延庆盆地西北缘的狼山山前断裂进行考察。在一些地点经探槽揭示:在小四村北约500米处的冲沟北侧的剖面上,发现了地震崩积物、地震楔、分枝断层的截顶等古地震的地质构造地层标志。初步分析表明,该断裂自晚更新世中期以来发生过四次地表破裂事件,其强度可达7—7.5级。据北京及周围地区1476—1988年M≥4.7级强震的地震活动图象,延庆—蔚县地区在未来几十年或更长一些时间内有发生M≥6(?)级大震的可能。结合地震构造和古地震的背景信息,延庆盆地及邻区应列为首都圈地震监视的重点地区。更多还原

【Abstract】 Three times of field investigation were done in 1988, along the Langshan Mountain-front fault located at the NW edge of the Yanqing basin. By excavation at some places, structuro-geological and stratigraphical marks of paleo-earthquakes, such as coseismic calluvium, wedges and truncated fault branches have been found in the profile at the north side of a gully about 500 m north of Xiaosicun village. Preliminary analyses show that there have been four events of surface rupturing along the fault since the midst of late pleistocene, and that the magnitude of the paleo-shocks might reach 7 to 7.5. According to the seismic pattern of strong shocks with M≥4.7 in Beijing and its adjacent regions in 1476-1988, the Yanqing-Yuxian region possesses the possibility of occurring strong earthquake with M≥6.5 in several decades or longer. Considering the background of seismotectonics and paleoearthquake information, we suggest that the Yanqing basin and its adgacent region should be taken as a key area for seismological surveillance of the Capital Circle.更多还原