摘要
通过对滇西地区43个台站对近5 a的直达Rayleigh波走时偏移时间序列进行综合处理,提取出适用于滇西地区M_(S)≥5.0地震的波速时变异常识别指标(综合指标),并结合研究时段内发生在滇西地区的7次M_(S)≥5.0地震事件,采用R值评分法对综合指标进行预测效能评价。结果表明:1)该综合指标对2020年以来发生在滇西地区M_(S)≥5.0地震的发震时间具有较好的指示意义,在通过置信度97.5%显著性检验(R>R_(0))的前提下,综合指标的最佳预测窗长为90 d,对于实际发生的7次M_(S)≥5.0地震,综合指标准确预测地震7次,漏报0次,虚报5次;2)研究区M_(S)≥5.0地震震中与震前(指标出现时)异常台站对分布对应关系表明,通过背景噪声波速时变测量所监测到的前兆信息,更多应该是“场兆”,而非“源兆”。在实际的地点预测中需结合地震活动异常区域(如空区、条带)及重力、流动地磁等成场观测得到的异常区,寻找可能的发震地点,才能提高地点预测的准确率。
In order to better promote the application of time-varying measurement results of ambient noise wave velocity in earthquake tracking and earthquake prediction,this paper comprehensively processes the time series of direct Rayleigh wave travel time migration in 43 stations in western Yunnan in the past five years,and extracts the time-varying anomaly identification index(comprehensive index)of wave velocity suitable for M_(S)≥5.0 earthquakes in western Yunnan.Combined with the seven M_(S)≥5.0 earthquake events in western Yunnan during the study period,the R-value scoring method was used to evaluate the prediction efficiency of the comprehensive index.The results show that:1)The comprehensive index has a good indication for the occurrence time of M_(S)≥5.0 earthquakes in western Yunnan since 2020.Under the premise of passing the significance test of 97.5%confidence level(R>R_(0)),the best prediction window length of the comprehensive index is 90 d.For the actual occurrence of 7 M_(S)≥5.0 earthquakes,the comprehensive index accurately predicts 7 earthquakes,omits 0 earthquakes,and falsely reports 5 earthquakes.2)The corresponding relationship between the epicenter of M_(S)≥5.0 earthquakes in the study area and the distribution of abnormal stations before the earthquake(when the index appears)shows that the precursory behavior monitored by the time-varying measurement of ambient noise wave velocity should be more‘field precursor’,rather than‘source precursor’.In the actual location prediction,it is necessary to combine the abnormal areas of seismic activity(such as empty areas and bands)and the abnormal areas obtained by field observations such as gravity and mobile geomagnetic to find possible earthquake locations,so as to improve the accuracy of location prediction.
作者
杨建文
叶泵
金明培
杨芬
李见
段美芳
YANG Jianwen;YE Beng;JIN Mingpei;YANG Fen;LI Jian;DUAN Meifang(Yunnan Earthquake Agency,Kunming 650224,China;Field Scientific Observation and Research Station on Crustal Tectonic Activities in Northwest Yunnan,Dali 671000,China)
出处
《大地测量与地球动力学》
北大核心
2026年第2期201-206,共6页
Journal of Geodesy and Geodynamics
基金
中国地震局震情跟踪定向工作任务(CEA-ZQGZ-202501032)
中国地震局地震科技星火计划(XH23034YA)
云南省地震科技创新团队(CXTD202506)
云南省地震局地震科技专项基金(2023ZX01)。
关键词
滇西地区
背景噪声
波速时变异常
综合指标
效能评价
western Yunnan
ambient noise
anomaly of wave velocity time-varying
comprehensive index
effectiveness evaluation
