【摘要】 全新世以来岷江断裂带古地震参数是地震潜势评价的重要基础.通过对比漳腊盆地黑斯沟沟口T2阶地前缘的大型探槽剖面的沉积层,将沉积序列分为两套地层.下部为青灰色河流相冲洪积砾岩层,上部为浅黄色至灰白色滨湖相粉细砂层、冲洪积相砾石层夹泥炭层.通过对比地层的错动、坎前堆积、地层产状变化等要素识别出3次古地震事件,同震垂直落差约1.5m.依据地震震级、同震位移、同震破裂尺度之间的关系,可推测岷江断裂带古地震震级约7.1.初步判定复发周期在2 557~3 410a.考虑目前断层陡坎的埋藏形态接近震前形态,离逝时间亦较长,汶川地震后,该区地震危险性应引起重视.更多还原

【Abstract】 The paleo-earthquake parameters of Minjiang fault in Holocene provide the important data for seismic potential assessment.One large trench lies in front of terraceⅡ,in the estuary of Heisi gully,in Zhangla basin,along the Minjiang fault.Sedimentary sequences can be divided into two layers,with the light blue alluvial gravel strata in the lower and the light yellow to gray gravel layer of peat layer in the upper.Three paleo-earthquake events can be identified by the dislocation of the strata,and the vertical drop is about 1.5mthat accompany with each event,and simultaneous make the dip of the strata changed.According to the statistical regularity between the magnitude,the co-seismic displacement and the long rupture,the magnitude is concluded to be at 7.1.Based on the age of the 14 C in the lower A mark layer,we can conclude that the recurrence period is2 557-3 410a.Considering the current shape of fault scarp close to the buried shape of pre-earthquake,we should pay more attention to the seismic risk in this region after the Wenchuan earthquake.更多还原