长江经济带中-东部地区地壳形变数值分析

Numerical analysis on the current crustal deformation in mid-eastern Yangtze River economic belt

长江经济带是具有全球影响力的内河经济带,也是我国综合实力最强最大的区域之一.长江经济带中-东部地块构造相对稳定,但仍存在一些可能造成潜在威胁的活动断裂.随着我国大陆环境监测网络工程实施,华南地区已开展了大量GPS速度场观测工作.据此,本文选取长江经济带中东部区域为主要研究对象,基于活动构造、深部地球物理和现今GPS速度场等资料,建立长江经济带地区三维有限元数值地质模型.以GPS速度观测数据为约束,计算长江经济带在现今构造驱动下的区域应变和应力场,进而分析和探讨在构造加载下长江经济带中东部现今地壳变形趋势,初步评估了区域地震危险性.研究结果初步显示该区域应变率积累量级约为10^(-9)/a,主要活动断层上库仑应力增加约50～200 Pa/a,说明长江经济区构造变形和应力积累过程相对微弱,处于构造相对稳定的状态.

The Yangtze River economic belt is an inland-river economic belt with global impact,which is one of the most powerful and comprehensive area in China.The mid-east part of the economic belt is tectonically stable,but is still distributed with active faults of potential seismic hazard.With the development of GPS networks in the mainland of China,there has been plenty of GPS observations in South China block.Therefore,we construct a high resolution 3-D FEM geodynamic model of mid-east part of Yangtze River economic belt,based on the active tectonics, geophysical observations and GPS velocities.Constrained by the GPS velocities,we calculate the strain rate and changes of crustal stress,and further comprehensively analyze the current crustal deformation,and seismic hazard in this region.Our numerical results show that the crustal strain rate is in a magnitude of 10^-9/a,and the Coulomb stress changes of the major active fault are approximately 50-200 Pa/a in the research area.The comparatively small strain rate and stress changes suggest the stable tectonic settings of the mid-east part of Yangtze River economic belt.