Shallow Tectonic Characteristics of the Haihe Fault in Tanggu Area,Tianjin Municipality

In this paper,based on the high-resolution acoustic seismic profile data and the borehole stratigraphic data surveyed in the Haihe River area,the shallow stratigraphic structures and fault activity characteristics of the Haihe Fault in Tanggu area,Tianjin municipality are studied.It is shown from the study results that 4 marine facies strata in the late Quaternary stratum are characrized by steady horizon and seismic facies easy to be traced.On the acoustic seismic profile,reflectors R_1,R_2,R_3,R_4,R_5,R_6,R_7,R_8 and R_9 are identified downward from the riverbed reflector R_0,and they are boundaries between two stratigraphic units,including Holocene land facies stratum,marine facies stratum Ⅰ,marine-land alternating facies stratum,land facies stratum Ⅱ,marine facies stratum Ⅱ,land facies stratum Ⅲ,marine facies stratum Ⅲ,land facies stratum Ⅳ and marine facies stratum Ⅳ,respectively.In addition,it is shown from the study results that the upper breaking points of the Haihe Fault in the area are located at 50 to 55 ms depths below the Haihe River surface,which is basically consistent with the borehole data,and the latest active period of the Heihe Fault is about in the late stage of late Pleistocene.