遮放-宾川岩石圈剖面应力状态研究

STUDY OF STRESS STATE IN LITHOSPHERE PROFILE IN ZHEFANG-BINCHUAN

选取遮放———宾川长３５０ｋｍ，深１２０ｋｍ剖面，建立不同模型，利用有限元法进行数值模拟，探讨该区地壳、上地幔的应力分布，计算表明：在线弹性介质中应力分布不仅受断层结构的控制，而且还受物性参数的控制。壳内低速层和断层属物性软弱层，应力在其边缘或邻区较硬介质内较高，与地震一般发生在软弱层与较硬层交界处或软弱层周围物性较硬的部位的特点一致。故认为低速层和断层的作用可能是地震孕育的主要物性和结构环境因素之一。怒江断裂及其上地壳底部的低速层控制着龙陵潞西的地震，金沙江红河断裂的影响及中地壳低速层的作用使大理下关地区成为地震多发地带。

tress distribution in crust and upper mantle has been explored using numerical simulation of finite element method by selecting a profile with length of 350 km and depth of 120 km in Zhefang-Binchuan and establishing different models. The calculation indicates that the stress distribution in linear elastic media is not only controlled by fault structure, but also by parameters of physical property. The low velocity layer in crust and fault belong to weak layer in physical property, where the stress is higher comparing with hard media, which is coincided with features that earthquake generally occurs in the border area between weak layer and hard layer, or in the position in ambient weak layer where is harder in physical property. Therefore it is considered that interaction between low velocity layer and fault could be one of the main physical property and structural environment in seismogenesis. The Nujiang fault and the low velocity layer at the bottom of upper crust has controlled the earthquake in Longling-Luxi, the effect of Red River Fault of Jinshajiang and the function of low velocity layer in mid-crust has made Dali-Xiaguan region become earthquake-prone zone.