中国大陆岩石圈有效弹性厚度与强震构造区力学特征研究

Study on the Effective Elastic Thickness of Lithosphere and Mechanical Characteristics of Great Earthquake Tectonic Areas in the Chinese Mainland

研究中国大陆强震区岩石圈力学特性对理解该区强震孕育环境及发生机理具有重要意义。岩石圈有效弹性厚度(Te)及初始载荷比(F)与大陆岩石圈力学特征紧密相关。本文利用导纳和相关函数联合反演方法以及贝叶斯最优参数估计方法,基于全球最新的WGM2012重力异常数据、ETOPO1地形数据和CRUST1.0模型的Moho面深度数据,计算中国大陆岩石圈有效弹性厚度(Te)和初始载荷比(F)。通过对比分析,探索该地区岩石圈Te、F、Te梯度和F梯度对强震孕育环境的影响作用。本文发现,强震构造区岩石圈一般具有较低的Te值、较高的Te和F梯度值。结果表明,岩石圈综合力学强度较低且力学强度和内部载荷变化剧烈的地区,往往更有利于强震的孕育。

Studying the mechanical characteristics of the lithosphere in the areas where strong earthquakes have often happened are of significance for exploring the occurrence mechanisms of strong earthquakes.The lithosphere effective elastic thickness(T_e)and initial loading ratio(F)are closely related to the mechanical characteristics of the continental lithosphere.We use a new joint inversion method integrated both admittance and coherence techniques to compute the effective elastic thickness and initial loading ratio in the Chinese mainland,with the WGM2012 gravity data,ETOPO1 topographic data,and the data of Moho depth and crustal density from CRUST1.0 model.Based on the estimated T_e and F,we discuss that how the parameters of T_e,F,and gradients of them affect the environment for the development of strong earthquake.We find the high-degree earthquake tectonic areas tend to low T_e and high gradients of T_e and F.These suggest that the regions with a relatively low lithosphere strength,and those at the belts with sharp changes of lithosphere strength and internal load can provide a positive environment for developing strong earthquakes.