山东海阳断裂东石兰沟段晚更新世以来地表断错特征与最大潜在地震估计
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摘要
海阳断裂是胶东半岛NE向牟平 -即墨断裂带东部一条规模较大的断裂 ,尽管晚更新世以来该断裂的地表断错活动总体上已基本停息 ,但东石兰沟段在晚更新世晚期以来仍有断错地表的活动。最后一次断错地表的活动发生在距今 3 7～ 1 2万年 ,但接近 1 2万年。地表破裂长度约6 5km ,活动段长度 8km。地表断错以走滑活动为主 ,可见最大倾滑位移 0 2m ;根据断层擦痕侧伏角推测最大水平位移 1 13m。最后一次断错地表的活动若以距今 1 2万年计算 ,则最大平均倾滑速率为 0 0 17mm/a ;最大平均右旋走滑速率为 0 0 94mm/a。野外观测到该活动段的断错活动表现为突发断错 ,根据地震地表破裂参数、活动段长度与地震的关系 ,估计其最大潜在地震为 6 级。
The Haiyang fault of 115km length is a larger scale fault in the east of the NE striking Mu ping Jimo Fault zone in Jiaodong Peninsula, Shandong Province. This fault showed intense surface faulting during middle Pleistocene, while dip slip reverse displacement of larger than 1m on the fault can be identified in the field. Although the surface faulting along the fault has generally ceased since late Pleistocene, late Pleistocene surface faulting still occurred on the Dongshilangou segment of the fault. The Length of the Dongshilangou segment is about 8km. Detailed investigation along the segment shows that the latest surface faulting event occurred at 37～12ka B.P., and most possibly near 12ka B.P. The surface faulting has a total length of 6.5km or more, and is dominated by right lateral strike slip with small amount of dip slip reverse component. The observable maximum dip slip displacement is about 0.2m, and the right lateral displacement is about 1.13m as deduced from the plunge of fault striae. The average right lateral strike slip rate is estimated to be 0 094mm/a and the dip slip rate to be 0.017mm/a, with the assumption that the latest surface faulting event occurred at 12ka B.P. The geologic profile of this active segment indicates that the late Pleistocene surface faulting on this fault was an abrupt faulting event. According to the relationship between the parameters of seismic surface faulting and the rupture length, it is estimated that the maximum magnitude of the potential earthquake on this segment may reach 61/4.
The Haiyang fault of 115km length is a larger scale fault in the east of the NE striking Mu ping Jimo Fault zone in Jiaodong Peninsula, Shandong Province. This fault showed intense surface faulting during middle Pleistocene, while dip slip reverse displacement of larger than 1m on the fault can be identified in the field. Although the surface faulting along the fault has generally ceased since late Pleistocene, late Pleistocene surface faulting still occurred on the Dongshilangou segment of the fault. The Length of the Dongshilangou segment is about 8km. Detailed investigation along the segment shows that the latest surface faulting event occurred at 37～12ka B.P., and most possibly near 12ka B.P. The surface faulting has a total length of 6.5km or more, and is dominated by right lateral strike slip with small amount of dip slip reverse component. The observable maximum dip slip displacement is about 0.2m, and the right lateral displacement is about 1.13m as deduced from the plunge of fault striae. The average right lateral strike slip rate is estimated to be 0 094mm/a and the dip slip rate to be 0.017mm/a, with the assumption that the latest surface faulting event occurred at 12ka B.P. The geologic profile of this active segment indicates that the late Pleistocene surface faulting on this fault was an abrupt faulting event. According to the relationship between the parameters of seismic surface faulting and the rupture length, it is estimated that the maximum magnitude of the potential earthquake on this segment may reach 61/4.
引文
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InsituteofGeology,StateSeismologicalBureau,SeismologicalBureauoftheNingxiaHuiAutonomousRegion.1990.TheActiveHaiyuanFaultZone〔M〕.Beijing:SeismologicalPress(inChinese).
唐荣昌,韩渭滨.1993.四川活动断裂与地震〔M〕.北京:地震出版社.
TANGRong chang,HANWei bin.1993.ActiveFaultsandEarthquakesinSichuanProvinces〔M〕.Beijing:Seis mologicalPress(inChinese).
WellsDL ,CoppersmithKJ .1994.Newempiricalrelationshipamongmagnitude,rupturelength,rupturewidth,rupturearea,andsurfacedisplacement〔J〕.BullSeismSocAmer,84(4):974～1002.
DINGGuo yu,TIANQin jian,KONGFan chen,etal.1993.SegmentationofActiveFault—Principle,MethodandApplication〔M〕.Beijing:SeismologicalPress(inChinese).
邓起东,于贵华,叶文华.1992.地震地表破裂参数与震级关系的研究〔A〕.见:国家地震局地质研究所编.活动断裂研究(2).北京:地震出版社.247～264.
DENGQi dong,YUGui hua,YEWen hua.1992.Relationshipbetweenearthquakemagnitudeandparametersofsurfacerupturesassociatedwithhistoricalearthquakes〔A〕.In:InstituteofGeology,SSB ,ed.ResearchonAc tiveFault(2).Beijing:SeismologicalPress.247～264(inChinese).
董瑞树,冉洪流,高铮.1993.中国大陆地震震级和地震活动断层长度的关系讨论〔J〕.地震地质,15(3):395～400.
DONGRui shu,RANHong liu,GAOZheng.1993.TherelationshipbetweenearthquakemagnitudeandlengthofactivefaultinChina〔J〕.SeismologyandGeology,15(4):395～400(inChinese).
国家地震局地质研究所,宁夏回族自治区地震局.1990.海原活动断裂带〔M〕.北京:地震出版社.
InsituteofGeology,StateSeismologicalBureau,SeismologicalBureauoftheNingxiaHuiAutonomousRegion.1990.TheActiveHaiyuanFaultZone〔M〕.Beijing:SeismologicalPress(inChinese).
唐荣昌,韩渭滨.1993.四川活动断裂与地震〔M〕.北京:地震出版社.
TANGRong chang,HANWei bin.1993.ActiveFaultsandEarthquakesinSichuanProvinces〔M〕.Beijing:Seis mologicalPress(inChinese).
WellsDL ,CoppersmithKJ .1994.Newempiricalrelationshipamongmagnitude,rupturelength,rupturewidth,rupturearea,andsurfacedisplacement〔J〕.BullSeismSocAmer,84(4):974～1002.
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