2022年四川马尔康M6.0震群前区域b值时空特征  

Research on the spatiotemporal characteristics of the b-value in the area before the M6.0 Malkang earthquake swarm in Sichuan in 2022

作　　者：郭瑛霞 张丽峰[1] 黄浩[1] 胡维云 GUO Yingxia;ZHANG Lifeng;HUANG Hao;HU Weiyun(Qinghai Earthquake Ageney,Qinghai Xining 810001,China)

机构地区：[1]青海省地震局,青海西宁810001

出　　处：《四川地震》2022年第3期1-5,共5页Earthquake Research in Sichuan

基　　金：2022年度震情跟踪定向工作任务(2022010504);2022年青海省地震局地震科学基金课题(2022B01)共同资助.

摘　　要：根据中国地震台网提供的地震目录,选取2009年1月至2022年6月的小地震资料,对马尔康震群及邻区进行b值时空扫描计算。采用“最大曲率”方法,评估得到2009~2016年马尔康地区的监测能力为M_(L)1.5,2017~2022年马尔康地区的监测能力为M_(L)1.2;从2009~2022年的b值时间扫描结果可知,5级以上地震大多发生在b值下降时段内;2017~2022年的b值空间扫描结果显示:2022年马尔康震群发生在松岗断裂和龙日坝断裂附近高低b值变化的过渡区域,靠近低b值区域的边缘,且震中北部区域Δb值异常显著,表明马尔康6.0级震群前邻区应力水平明显增强,压应力积累指示此区域及邻区易于发生地震。According to the earthquake catalogues provided by the China Earthquake Networks,we selected the data of small earthquakes from January 2009 to June 2022,and calculated the b-values of the Malkang earthquake swarm and adjacent areas by spatiotemporal scanning.Using the "maximum curvature" method,we suggest that the monitoring capability of the Malkang area from 2009 to 2016 is M_(L)1.5,whereas the corresponding value from 2017 to2022 is M_(L)1.2.From the b-value time scan results from 2009 to 2022,we suggest that most earthquakes of the M_(s)≥5.0 occurred during the decline period of b-value.The results of the spatial scan distribution of b-values show that the Malkang earthquake swarm in 2022 occurred in the transition area between high and low b-value changes near the Songgang fault and the Longriba fault.The swarm is close to the edge of the low b-value region.Moreover,the Δb-value in the northeastern part of the fault is abnormally significant,which indicates that the stress level in the adjacent area before the M6.0 Malkang earthquake swarm is significantly enhanced.Furthermore,the accumulation of compressive stress indicates that earthquakes are prone to be occurred in the area and adjacent areas.

关 键 词：2022年马尔康6.0级震群 最小完整性震级 B值 时空分布 

分 类 号：P315.72[天文地球—地震学]