广西主要断裂带中小地震应力降特征分析

Feature of Stress Drop of Medium and Small Earthquakes in the Main Fault Zone in Guangxi

选取广西数字地震台网记录到的2007年至2013年广西主要断裂带ML≥2.5地震事件,采用Atkinson方法反演得到介质品质因子Q值,采用Moya方法得到各台站场地响应,在此基础上计算得到90个位于主要断裂带及附近的中小地震应力降,并对其应力降空间分布特征进行分析。研究结果表明,应力降值主要分布在1~10 MPa之间,占58%,主要分布在百色—合浦断裂中段以及与桂林—南宁断裂交汇区域;小于1.0 MPa（低应力降）的地震占37%,主要分布在桂西北地区;10 MPa及其以上的（高应力降）地震主要分布在桂东南,且历史上曾经发生过5级以上地震的原震区及附近,反映了原震区及其附近仍具有高应力背景。

Based on data of earthquakes with ML≥2.5occurred in the main fault zone in Guangxi,recorded by Guangxi Digital Seismic Network from 2007 to 2013,the medium quality factor（Q）is figured out by inversion using Atkinson method.Then site response of each station is gotten by using Moya method.On these bases,stress drop of 90 medium small earthquakes around in the main fault zone are calculated.Spatial distribution characteristics of the stress drop are analyzed.The results show that 58% stress drops（Δσ）are within 1~10MPa,mainly distributed in middle section of Baise-Hepu Fault and in juncture region of Guilin-Nanning Fault,Δσless than 1.0 MPa（Low stress drop）are mainly in Northwestern Guilin andΔσlarger than 10.0 MPa（High stress drop）are mainly in Southeastern Guilin where earthquake with M≥5.0occurred in history,which reflects that the original earthquake region and nearby still has a high stress background.