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Title:: Characteristics of Crustal Deformation Anomalies before the Hutubi M_S6.2 and Jinghe M_S6.6 Earthquakes

作者:: 张希¹; 方伟²; 秦姗兰¹; (1.中国地震局第二监测中心,陕西西安 710054; 2.新疆维吾尔自治区地震局,新疆乌鲁木齐 830011)

Author(s):: ZHANG Xi¹; FANG Wei²; QIN Shanlan¹; (1.The Second Monitoring and Application Center,China Earthquake Administration,Xi’an 710054,Shaanxi,China)(2.Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,Xinjiang,China)

Keywords:: North Tianshan area; the Hutubi earthquake; the Jinghe earquake; GPS; index of cross-fault deformation; grey relativity index

摘要:: 利用2012—2018年跨断层流动水准观测资料,提取北天山地区的断层形变趋势累积率和灰色关联度指标,结合2009—2017年GPS速度场数据,分析呼图壁M_S6.2与精河M_S6.6地震前的地形变异常特征。结果表明:① 呼图壁地震位于GPS压性变化最高值区边缘,断层形变趋势累积量较大的测线相对集中在震区附近; 精河地震位于压应变较高值区和增强区,震区附近也出现巴音沟、伊宁等跨断层高逆断趋势累积背景异常。② 2次地震中,震级较大的精河地震前跨断层灰色关联度指标异常较为显著,震中周边半径200,300,500 km范围内均出现“逆断加速”中短期-短期异常; 且距震中越近,异常幅度越大。

Abstract:: Using the observational data of mobile cross-fault leveling during 2012-2018,the trend accumulation rate and grey relativity index of fault deformation in North Tianshan area are extracted for the first time.Combined with the GPS velocity field result during 2009-2017,the characteristics of crustal deformation anomalies before the Hutubi M_S6.2 and Jinghe M_S6.6 earthquakes are comprehensively analyzed.The results show that:(1)The Hutubi earthquake was located at the edge of the highest value area of GPS compressive variation; observational lines with larger trend accumulation of fault deformation were relatively concentrated near the seismic area.The Jinghe earthquake was located in the higher compressive strain area and the enhancing area,there were also high thrust trend accumulation background abnormities such as Bayingou and Yining near the seismic area.(2)Among these two earthquakes,the Jinghe earthquake with larger magnitude had relatively obvious medium-short-term and short-term “thrust accelerating” anomalies in the range of 200 km,300 km and 500 km from the epicenter; and the nearer to the epicenter,the greater the anomaly amplitude.