Abstract: There exist several groups of seismogenic active faults at the conjoined areas of the Chuandian,Bayankala and Huanan active blocks along the eastern margin of the Qinghai-Tibetan Plateau. Owing to existence of transverse secondary active faults,the Chuandian Block can be further divided into the Middle Yunnan and Northwestern Sichuan sub-blocks,and the Longmenshan sub-block at the easternmost end of the Bayankala Block. Joint exploration of the crustal structure shows that low-velocity layers exist in the crust of the Chuandian and Bayankala Blocks. These low velocity layers correspond also to high conducting layers and they are the cause of frequent earthquake occurrence in the upper crust. Geologic study and GPS surveying indicate that the tectonic motion of the blocks in this region is accounted to be a complex or superimposition of three basic types of motions: southeastward sliding,rotating on vertical axis,and uplifting,but there is difference in the geologic slip rate and GPS rate. Besides,this paper collects the database of the geologic slip rates and GPS slip rates for the active faults in the region and major scientific problems are also discussed at last.

Key words: active tectonics, active blocks, recurrence behavior of strong earthquake, western Sichuan Province

摘要： 川西及其邻近地区位于青藏高原东缘川滇、巴颜喀拉和华南三大活动块体的交接部位,发育着多组具有发震能力的活动断裂。由于横向次级活动断裂的存在,川滇块体可进一步划分为滇中和川西北2个次级块体,巴颜喀拉块体可划分出东端的龙门山次级块体。深部探测反映出川滇和巴颜喀拉块体地壳中均存在着低速-高导层(体),它们是上地壳多震的原因之一。地质研究和现今GPS观测表明:各级块体均存在着SE向或SSE向平移运动、顺时针转动和隆升运动,但量值存在着一定差异。文中还给出了各主要活动断裂带的地质或GPS滑动速率,讨论了目前存在的主要科学问题。

关键词: 活动构造, 活动块体, 强震复发模型, 川西