2020年6月26日于田MS6.4地震前的多重地震参数异常研究

STUDY ON MULTIPLE SEISMIC PARAMETER ANOMALIES BEFORE YUTIAN MS6.4 EARTHQUAKE ON JUNE 26TH,2020

2020年6月26日在新疆于田县发生MS6.4地震,在震前观测到多种地震参数异常。这些参数揭示了地震发生前的区域应力积累、岩石扩容及断层失稳3个过程,可能反映了一些地震从长期到短期孕育过程的关键性特征。主要包括3个方面:(1)图像信息(PI)分析结果显示于田地区存在显著的背景应力异常,其幅度指示了6级以上地震的潜在可能。(2)加卸载响应比(LURR)的时空演化进一步显示震源区介质应力状态在2019年发生了明显改变:LURR在2019年出现明显异常高值,并持续至2020年后开始减弱,意味着短期内有可能发生较强地震。(3)地震矩释放出现了显著的加速特征(AMR),拟合预测的地震震级为生M S6.2,发震时间为2020年5月。基于此,在中国地震台网中心年度地震趋势会商会上预测于田地区2020年存在发生6级地震的可能。

On June 26th,2020,an earthquake with magnitude 6.4 occurred in Yutian County,Xinjiang.We have observed a variety of seismic parameter anomalies before the earthquake.These parameters reveal three processes of regional stress accumulation,rock dilatation and fault instability before the occurrence of earthquakes,which may reflect the key characteristics of the long-term to short-term incubation process of some earthquakes.They are:(1)the Pattern informatics(PI)show significant anomalies in Yutian area,which implies the potential for a large earthquake with magnitude greater than 6.0.(2)The spatial evolution of Load/Unload Response Ratio(LURR)further shows the intermediate-to-short-term earthquake potential,which markedly enhanced in 2019 and decreased in 2020.The changes could be evidenced by the evolution of LURR time series.(3)the Benioff strain release is accelerated obviously,and the time and magnitude of earthquake can be derived as May 2020 and M S6.2.Based on this,it is predicted at the annual earthquake trend meeting of China seismic network center that there will be a possibility of M S6.0 earthquake in Yutian area in 2020.