新疆阜康断裂带甘河子段晚第四纪活动特征

Late-Quaternary Activity Characteristics of the Ganhezi Segment of the Fukang Fault Belt,in Xinjiang

为了解阜康断裂晚第四纪以来的活动特征,准确评价该断裂的大震危险性,在野外地震地质调查的基础上,对变形的微地貌进行了测量,开挖了2个大型古地震探槽,并采集了系列释光年龄样品,对阜康断裂甘河子段进行了细致研究.甘河子断裂段是一条全新世活动断裂,全长约33km,构成博格达北麓与山前冲洪积扇的界线.该断裂晚第四纪期间活动性较强,运动方式以向盆地方向的逆冲为主,形成了一系列地质地貌现象.晚第四纪晚期以来,断裂的平均垂直滑动速率在0.34～0.43mm/a.全新世中期以来,断裂有过2次古地震事件,断裂大震(特征地震)的复发周期为2100～3750a,最新一次古地震事件造成的地表垂直位移量为1.5m左右,对应的古地震震级在7.2～7.4之间,该次古地震事件离逝时间已达4.11ka,目前该断裂已经累积了较高能量.

In order to understand the activity characteristics of the Fukang fault in Late-Quaternary, and accurately estimate the seismic hazard of the fault, a geological survey has been conducted along the Fukang fault. By surveying the deformation micro- topography, excavating two large paleoearthquake trenches, and dating a series of samples of thermoluminescence, the quantity activity characteristics of the Ganhezi fault segment of the Fukang fault belt are revealed. The Ganhezi fault segment is a Hol ocene active fault, with a total length about 33 km. The fault activity is obvious, generating a series of apparent geomorpbic traces on the surface. Since the Late-Quaternary, the average vertical slip rate of fault is about 0. 34--0. 43 mm/a. Since the Mid-Holocene, there were two paleoearthquake events; the strong earthquake recurrence period of the fualt segment is about 2 100--3 750 a. The vertical surface displacement is about 1.5 m and the elapsed time is 4. 11 ka of the latest paleoearthquake, corresponding to the paleoearthquake magnitude of between Ms7.2--7.4. The fault has accumulated a high energy so far.