广西及邻区地震目录最小完整性震级时空分布研究

Research on the Spatial and Temporal Distribution of Minimum Magnitudeof Completeness for Earthquake Catalog in Guangxi and Its Adjacent Areas

基于广西区域测震台网测定的1970年以来地震事件,采用震级-序号法、MAXC方法以及GFT方法分析M_C时间演化特征,运用EMR方法研究M_C空间分布情况。结果表明,随着测震台站数量增加和布局优化,广西及邻区地震监测范围和震级逐时段明显增强,且M_C值整体下降。时间序列显示,广西及邻区M_C值在1970~2007年为2.0~2.5,2008~2016年为1.8~1.9,2017年后降至1.4~1.8。不同时段桂西、桂东南及桂北地区M_C空间不均匀性较为显著,桂西地区M_C较小,桂东南地区次之,桂北地区最大;2008年后,桂西地区M_C为0.6~1.6,桂东南和桂北地区为1.8~2.0。

Based on the earthquake events since 1970 measured by the Guangxi regional seismic network,we use magnitude-rank,MAXC and GFT methods to analyze the temporal characteristics of minimum magnitude of completeness(M C),and use EMR method to analyze the spatial distribution of M C value.The results show that,with the increase in the number of seismic stations and the optimization of their layout,the scope and magnitude of seismic monitoring in Guangxi and its adjacent areas are significantly enhanced by time,and the M C value decreases as a whole.The time series shows that the M C value of Guangxi and its adjacent areas was about 2.0 to 2.5 from 1970 to 2007,1.8 to 1.9 from 2008 to 2016,but dropped to about 1.4 to 1.8 after 2017.The spatial heterogeneity of M C value in western,southeastern and northern Guangxi is relatively significant in different periods.The M C value in western Guangxi is small,followed by that in southeastern Guangxi and is largest in northern Guangxi.After 2008,the M C value in western Guangxi is 0.6 to 1.6,and that in southeastern and northern Guangxi is 1.8 to 2.0.