CAJ | 학술논문

用双差地震定位法对华北地区(111°～120°E,35°～42°N)1993-2004年6 771次地震(1.0≤M≤6.6)重新定位.重新定位后的结果显示:地震活动呈北东与北西向线性分布,与活动断裂关系密切;在新河断裂下方,存在两条走向北东、向西南倾斜的、不同深度的地震活动带,浅部的从地表向下延伸约20 km,长60 km,深部的从25 km到34 km,长约40 km;83%的地震震源深度位于0～15 km范围内,比由常规地震定位法给出的华北地区(7～21 km)的震源深度要浅得多,说明华北地区的地震基本都集中在中上地壳中;约有92%的地震震源深度位于1～24 km,表明24 km是华北地震构造区震源深度的下界.
용쌍차지진정위법대화북지구(111°～120°E,35°～42°N)1993-2004년6 771차지진(1.0≤M≤6.6)중신정위.중신정위후적결과현시:지진활동정북동여북서향선성분포,여활동단렬관계밀절;재신하단렬하방,존재량조주향북동、향서남경사적、불동심도적지진활동대,천부적종지표향하연신약20 km,장60 km,심부적종25 km도34 km,장약40 km;83%적지진진원심도위우0～15 km범위내,비유상규지진정위법급출적화북지구(7～21 km)적진원심도요천득다,설명화북지구적지진기본도집중재중상지각중;약유92%적지진진원심도위우1～24 km,표명24 km시화북지진구조구진원심도적하계.
We relocuted epicenters of totally 6 771 earthquakes which occurred in North China region (35°～42°N, 111°～120°E) from 1993 to 2004. The relocation shows those formerly randomly-distributed earthquakes are clustered and are aligned tending to the North-East and North-West directions. It follows that there is a close relationship between the seismicity and known major active faults. From the cross sectional profile beneath the Xinhe fault, the relocated seismic sources reveal two seismic belts of different depths. One of them is around 60km long and in the direction of north-east, its depth varies from the surface downwards to 20 km underground. The other is about 40 km in length and is from 25km to 30 km in depth.At the same time, we found that the 83 percent relocated hypocenters vary from 0 km to 15 km in depth. This is certainly more shallow than that from the previous studies which are based on the roubine earthquake location, whose average focal depth is within a range of 7～21km. This result indicates that the contemporary seismicity in North China region is mainly concentrated in the upper and middle crusts. Furthermore, about 92 percent focal depth is ranged from 1 km to 24 km, which is in good agreement with the consensus that the lower bound of the focal depth in North China region is 24 km.