摘要
矩震级标度是从地震矩换算过来的，换算关系中地震应力降与剪切模量估算的不准确会对矩震级标度产生影响．本文利用1976年1月～2006年12月发生在东经75°～135°，北纬15°～55°的M≥5地震的矩震级与面波震级，探讨了应力降与剪切模量的比值Δσ／μ在中国及邻区以及在不同震级下的分布特征．中国大陆及邻区的Δσ／μ值分布较分散，不同地区的Δσ／μ值明显不同，且绝大部分值大于矩震级和地震矩换算关系中使用的全球平均值．对于同一地区不同震级的地震，其Δσ／μ值也不一样，震级大，Δσ／μ值通常也大．研究认为剪切模量和地震应力降的估计对矩震级标度的影响不能忽略．
Moment magnitude is transformed from seigmic moment, so the estimation inaccuracy of stress drop and shear modulus will affect moment magnitude scaling. Using the seismic moments and surface wave magnitude of 5 earthquakes in longitude 75°～135°E and latitude 15°～55° N from January 1976 to December 2006, we discuss the distribution of the ratio of stress drop to shear modulus Δσ/μ in the China mainland and its adjacent regions, as well as its distribution features for different magnitudes. In the China mainland and its adjacent regions, the Δσ/μ ratios are dispersive and clearly different in different areas, and most of them are greater than the mean value used in the transform relationship of moment magnitude and seismic moment. Additionally, the Δσ/μ ratios are obviously different for the earthquakes with different magnitude in the same regions, usually the greater the magnitudes, the larger the Δσ/μ ratios. The results suggest that the effect of the estimation errors of stress drop and shear modulus on the moment magnitude scaling can not be neglected.
出处
《地球物理学进展》
CSCD
北大核心
2008年第3期705-709,共5页
Progress in Geophysics
基金
国家自然科学基金项目(40474016)资助
关键词
地震标度
矩震级
应力降
剪切模量
earthquake scaling, moment magnitude, stress drop, shear modulus
