中文摘要：

以青藏块体北部的北祁连山-河西走廊地震构造带为研究对象,在系统收集整理该区主干活动断裂新活动性特征、断裂滑动速率、历史地震及古地震资料的基础上,结合现今地震活动性,采用地震空区、空段识别方法和地震活动b值空间图像扫描方法,分析了研究区内历史地震及b值的分布特征。结果显示,该区的榆木山北缘断裂离逝时间较长,应力积累程度较高,具有发生大震的构造条件,其未来大震危险性最高,值得高度关注。其次,该区的嘉峪关断裂也存在地震空段和低b值段,也应引起重视。

英文摘要：

In recent years,many big earthquakes（M≥7） struck China and other nations.These big earthquakes may indicate that the earth is in a globally seismic active period.Therefore,in order to mitigate future earthquake disasters,the assessment of future big earthquake risk for major active boundary faults has been done as an important approach for mitigation.In this paper,our focus area is Northern Qilianshan-Hexi Corridor locating in northeastern of Qinghai-Tibet plateau.We collected and summarized the active faults＇ data sets systematically,e.g.geometrical characteristic,slip rate,rupture segmentation,latest rupture event and paleo-earthqakes.And based on these data sets,we use the methods of seismic gap identification and b value mapping to analyze the characteristics of historical earthquakes and b value.And then,high risk zones or faults of big earthquakes were identified synthetically.We think the Northern Yumushan Fault has the most probability of generating big earthquake in the future.Because the elapse time from the last event is long and b value along it is remarkably low,which betokens high stress.Meanwhile,attention should be paid too to the Jiayuguan Fault,where seismic gap and low b value zone exist too.