Abstract: Taiwan Island situated between the Eurasia and Pacific plates can be supposed as a part of Western Pacific seismic belt. On the basis of the characteristics of geological tectonics, gravity anomaly, crustal structure and seismicity, Taiwan Island and adjucent regions may be divided into three seismotectonic zones, they are: I) Seismote-ctonic zone of eastern Taiwan. There earthquakes occurred along the western margin of Philippino Sea basin and in the volcanic arc, longitudinal valley and foreland depre-sisson in Lan Yu and Huo Shao Dao Islet. It is characterized by strong seismicity, high frequency of earthquake, NNE running distribution of epicenters and the NW-NWW running orientation of regional principal compressive stress field; 2) Seismotectonic zone of western Taiwan. There earthquakes appeared along the Cenozoic folding belt of Taiwan and marginal depression. Both seismicity and seismic frequency in this zone are much less than that of the eastern zone. Here the epicenters are distributed along NNE direction and the predominant principal compressive stress runs in NW-near EW direction, and 3) Seismotectonic zone of northern Taiwan. There earthquakes took place along the intersection zone of Taiwan and Ryukyu arcuated system with strong magnitude (intensity) and high frequency. The predominant principal compressive stress disclosed by the focal mechanism appears to be the direction approximately SN-NNW.In general, seismicities in Taiwan Island and the adjacent regions are varying with the relative motion between the Chinese and the Philippine Sea plates. In accordance with the view of plate tectonics, there are two types of earthquakes occurred in the region, that are. interplate earthquakes and marginal earthquakes of intraplate (namely arcuated island type of earthquakes), influenced by the boundary motion of plates. From the interplate earthquakes may be also recognized trench type and collisional type of earthquakes. The former was distributed in seismotectonic zone of northern Taiwan; and the NW running faults revealed by the focal mechanism are mostly of thrust faults, occationally of normal faults. The mechanism of thrust faults probably reveals the earthquakes caused by underthrusting action of plates along the trench, while the mechanism of normal faults seems to be used to illustrate the earthquakes caused by exten-sional faulting of lithosphere beneath the Philippine Sea plate. The collision type of earthquakes, as a result of strike-slip thrusting between the Chinese and the Philippine Sea plates, are mainly distributed in seismotectonic zone of eastern Taiwan. As to the island arc. type of earthquakes, they were distributed in seismotectonic zone of western Taiwan resulting from NNE running strike-slip thrusting within earth's crust.

摘要： 本文在简要地论述了台湾岛及其周围地区的地质构造、重力异常、地壳结构和地震活动等特征的基础上划分了地震构造带,对台湾岛上7级以上强震的发震构造条件作了初步讨论,最后用板块构造观点探讨了本区地震的构造成因。