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本文介绍了利用钻孔构造地层学和年代学资料鉴定平原区隐伏活动断裂长期活动习性的一种新的方法和应用实例。通过夏垫断裂上下盘东柳河屯 1,2号钻孔地层剖面年代学的测定和岩性的分析与对比 ,定量地恢复了距今 2 6ka以来断裂上下盘的差异沉积历史和垂直错动过程 ,建立了鉴别古地震的构造地层学标志。在此基础上 ,将断裂两侧的累积垂直位移量作为定量约束条件从新到老恢复到每一次地表破裂型地震错动前的状态 (扣除后期的同震垂直位移量 ) ,可识别出 11次地表破裂型古地震事件。指出夏垫断裂上的地表破裂型地震复发行为与古气候环境之间存在着密切的相关关系 ,气候极度寒冷的末次冰期间亚冰期和鼎盛期 (距今 19 3～ 2 6ka)共发生 6次地表破裂型古地震事件 ,这一时期是夏垫断裂地表破裂型 (古 )地震丛状群集期 ,复发间隔介于 90 0～ 190 0a ,且多数仅 90 0～ 12 0 0a。末次冰期鼎盛期晚期到冰后期 (距今 0～ 19 3ka)的地表破裂型 (古 )地震服从准周期复发模式 ,复发间隔明显地增长 ,包括公元 16 79年三河 -平谷 8级地震在内的最近 5次地表破裂型(古 )地震的复发间隔介于 370 0～ 相似文献
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Earthquake recurrence on whole active fault zones and its relation to that on individual fault-segments 总被引：1，自引：0，他引：1
IntroductionEarthquake recurrence models established on activity behaviors of strong earthquakes are the bases of long-term earthquake prediction, seismic risk zonation, and seismic hazard assessment. A lot of studies have been carried out on earthquake recurrence behaviors for specific seismogenic sources or fault-segments, and a series of empirical recurrence models have been proposed, such as the time-predictable model and the slip-predictable model for earthquakes repeated at the previous … 相似文献
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We derive the relative moment rate function for the shocks with Mw > 5 in the 1997-98 central Italy seismic sequence, started with the Mw = 5.7, 09/26/97 00:33 event, by applying an empirical Green functionmethod. By using three conveniently placed broadband MedNet stations we obtain apparent source time functions indicating clear directivity effects for all of the analysed earthquakes, with rupture propagation generally directed outward from the epicentral area of the09/03/97 foreshock sequence. Taking a simple source model, forward modeling is utilized for determining fault parameters such as length, rupture propagation velocity and direction and, for the three major events,slip distribution. The effects of the break propagation directions onthe sequence evolution is discussed. A possible inconsistencyresults for the shallow 04/03/98 shock, which could be avoided if alink with the deep 03/26/98 event is assumed.Our analysis evidences the importance of a quick determination for the fault parameters in order to image the possible induction of fracturing on nearby structures. 相似文献
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Slip nucleation during earthquakes is apparently analogous to rupture nucleation within an intact rock sample subjected to triaxial loading. The observations indicate that both these nucleation processes initiate within a relatively small volume and in both the slip propagates unstably along a quasi-planar surface. In both processes a single, pre-existing, shear fracture cannot nucleate the large-scale slip, and in both a ‘process zone' that includes several interacting fractures in a small volume are required to initiate the unstable slip. Both processes require rupture of intact rocks, generate complex fracture geometry, and are associated with intense energy-release rate during slip. Recent observations and analyses are used to correlate rupture nucleation in laboratory tests with nucleation events of large earthquakes. It is proposed that earthquake nucleation occurs by the interaction among multiple fractures within a small volume that develops into unstable yielding of the healed fault zone. 相似文献
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