台湾地区强震发生的构造环境与地震活动性分析

AN ANALYSIS OF TECTONIC ENVIRONMENT AND CONTEMPORARY SEISMICITY OF FRONTAL OROGENY IN CENTRAL Taiwan Region

台湾中部造山带前缘呈现为一弧形逆冲构造体系 ,每个弧形带分别由多个不同尺度但各自独立的次级弧形构造组成 ,而每一个弧形构造都有其各自独立的几何学、运动学和动力学特征 ,是典型的褶皱 -逆冲带 ,但同时各个次级弧形构造间却又有自相似特性。在对台湾中部地区弧形逆冲构造体系的空间位置与地震活动间的关系分析基础上 ,归纳出中部弧型逆冲地震带的地震活动特征 ,以台湾东西地震区的构造划分和北部、中部与南部不同的弧陆构造现象 ,描述了台湾地区的近代地震活动 (190 0年以来的 10 0年间 )

The central part of Taiwan Region shows an arcuate thrust tectonics. Every arcuate belt is composed of a series of varying scales of sub arcs, which appear as a separate fold and thrust belt with independent characteristics of geometry, kinematics and mechanics and a self similar system as well. The kinematics of arc changes from thrusting on the top of the arc to the oblique thrusting and wrenching at the sections, and finally thrusts to the bottom of the arc. The arcuate thrust tectonics is composed of frontal, lateral and oblique ramps at depth. Each earthquake deformation belt is related to the independent arc. Strong earthquakes correspond to the large scale arcs, and medium earthquakes to the small ones, and even to the smaller sub arcs. Finally, the mapping analysis is carried out between the contemporary seismicity and the space area of the arcuate thrusting tectonic system in the central part of Taiwan Region, especially on strong Chi Chi aftershock series.