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2020年6月26日于田MS6.4地震前Benioff应变和地电场加卸载响应比异常研究
于晨1, 王淑艳2, 苑争一1, 王亚丽1, 岳冲1, 余怀忠1,3
1.中国地震台网中心, 北京 100045;2.中国电子科技集团公司电子科学研究院, 北京 100041;3.新疆维吾尔自治区地震局, 乌鲁木齐 830011
摘要:
加卸载响应比(Load/Unload Response Ratio,LURR)是根据岩石介质本构关系的动态演化特征提出的地震预测方法。2020年6月26日新疆于田县发生6.4级地震,震前以Benioff应变为响应量观测到明显的LURR高值异常,异常出现于2019年初,持续1年后发生地震,意味着震源区介质的应力状态在2019年发生了明显改变。进一步,以地电场为响应量,计算了距震中280km的和田地电场长、短极距共6个测向的LURR异常时序曲线,结果表明:和田地电场长、短极距的NS向和NW向共4个测向在震前1~3个月出现了LURR异常逐渐增大的同步变化,这种现象可能反映了孕震区介质因微裂隙的产生和扩展导致流体在裂隙中的运移引起的动电效应。综合分析2种不同响应量的LURR异常演化特征,有助于更深入地认知地震孕育过程,更准确地评估地震活动趋势。
关键词:  加卸载响应比  2020年于田MS6.4地震  Benioff应变  地电场
DOI:
分类号:P315
基金项目:国家重点研发计划(2018YFE0109700、2018YFC1503506)、国家自然科学基金(41942014)共同资助
LURR to Benioff Strain and Geoelectric Field before Yutian MS6.4 Earthquake of June 26,2020
Yu Chen1, Wang Shuyan2, Yuan Zhengyi1, Wang Yali1, Yue Chong1, Yu Huaizhong1,3
1.China Earthquake Networks Center, Beijing 100045, China;2.Academy of Electronics and Information Technology, China Electronics Technology Group Corporation, Beijing 100041, China;3.Earthquake Agency of the Xinjiang Uygur Autonomous Region, Urumqi 830011, China
Abstract:
Load/unload response ratio(LURR)is a method based on the dynamic evolution characteristics of constitutive relationship of rock media for earthquake prediction. On June 26,2020,the earthquake with magnitude 6.4 occurred in Yutian,Xinjiang. We have observed the LURR anomaly based on Benioff strain as the response before the earthquake. The characteristics of the anomaly in temporal and spatial evolution show that the stress state of the source area has changed significantly in 2019. LURR anomalies show the intermediate-to-short-term earthquake potential,which markedly enhanced in 2019 and decreased in 2020. After the earthquake,we calculated the LURR anomaly time series curves of six items of long and short polar distances of Hetian electric field 280km away from the epicenter. The results show that the synchronous variation of LURR anomaly gradually increases in in both north-south direction and north-west direction of the long and short polar distance of Hetian electric field about 1~3 months before the earthquake,which may reflect the electrokinetic effect of fluid migration in the fracture due to the generation and expansion of micro fractures in the seismogenic area. Comprehensive analysis of the characteristics of LURR anomaly evolution with two different responses is helpful to understand the process of earthquake generation and evaluate the trend of seismic activity more accurately.
Key words:  LURR  2020 Yutian Ms6.4 earthquake  Benioff strain  Geoelectric field