滇西北下关跨断层场地形变异常调查与机理分析
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摘要
对滇西北下关跨断层场地形变异常进行实地调研和考察,分析原始观测曲线,计算断层水平扭错、水平张压和垂直升降相对变化的累积量,讨论形变异常机理。结果表明:1)下关场地观测点位稳定,观测环境较好,无人为破坏或干扰现象,场地观测数据连续可靠;2)下关场地跨断层观测反映的断层背景活动方式为右旋活动,近期有所增强;3)下关场地断层形变中的压性异常波动与周边中强震、远场大地震有一定的对应关系;4)跨断层基线得到的水平张压累积量显示,地表断层存在持续的拉张活动,水准得到的垂直升降累积量显示,断层存在持续压性(逆断)活动,二者可以在统一的机理下得到解释,这对解释跨断层场地观测中存在的大量矛盾现象具有重要的参考价值。
In this paper,on-the-spot investigation and inspection is carried out for the fault deformation anomaly on Xiaguan site,northwest Yunnan province,and the original observation curves are analyzed.Furthermore,the accumulation of 3parameters:the relatively horizontal torsion,the relatively horizontal movement and the relatively vertical variation of the fault,are calculated respectively;and the mechanism of deformation anomalies is discussed.The results are:(1)the observation position of the Xiaguan site is stable,the observation environment is good,there is no artificial disturbance or interference phenomenon,and the observation data is continuous and reliable;(2)the crossfault observation of the Xiaguan site shows the fault has been being active as a right lateral slip,which has been enhanced recently;(3)there is a corresponding relationship between the abnormal compressional fluctuation of the fault deformation and strong earthquakes in the surrounding area;(4)the accumulation of horizontal compressional deformation from baselines across the fault shows that there is constant surface tensional fault activity.The accumulation of relative vertical deformation of the fault from leveling shows that the fault has a persistence of compressional fault(inverse)activities,and both can be explained under the mechanism of unity,which is of important reference value to explain the large number of contradictory phenomena in the observation of the cross-fault site.
In this paper,on-the-spot investigation and inspection is carried out for the fault deformation anomaly on Xiaguan site,northwest Yunnan province,and the original observation curves are analyzed.Furthermore,the accumulation of 3parameters:the relatively horizontal torsion,the relatively horizontal movement and the relatively vertical variation of the fault,are calculated respectively;and the mechanism of deformation anomalies is discussed.The results are:(1)the observation position of the Xiaguan site is stable,the observation environment is good,there is no artificial disturbance or interference phenomenon,and the observation data is continuous and reliable;(2)the crossfault observation of the Xiaguan site shows the fault has been being active as a right lateral slip,which has been enhanced recently;(3)there is a corresponding relationship between the abnormal compressional fluctuation of the fault deformation and strong earthquakes in the surrounding area;(4)the accumulation of horizontal compressional deformation from baselines across the fault shows that there is constant surface tensional fault activity.The accumulation of relative vertical deformation of the fault from leveling shows that the fault has a persistence of compressional fault(inverse)activities,and both can be explained under the mechanism of unity,which is of important reference value to explain the large number of contradictory phenomena in the observation of the cross-fault site.
引文
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[12]张兴华,李珊,宋金玲.用断层形变资料探讨滇西实验场区现今构造活动[J].地震研究,1994,17(4):362-369(Zhang Xinghua,Li Shan,Song Jinling.Exploration of Modern Tectonic Movement in WYEPSA by Data of Fault Deformation[J].Journal of Seismological Research,1994,17(4):362-369)
[13]徐锡伟,闻学则,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学D辑:地球科学,2003,33(增1):151-162(Xu Xiwei,Wen Xueze,Zheng Rongzhang,et al.The Latest Tectonic Variation of the Active Block in Sichuan-Yunnan Area and Its Power Source[J].Science in China Series D:Earth Sciences,2003,33(S1):151-162)
[14]李淑玲.山西跨断层形变测量场地布设分析[J].山西地震,1994(3):13-17(Li Shuling.Analysis of the Site Layout of the Across-Fault Deformation Measurement in Shanxi Province[J].Earthquake Research in Shanxi,1994(3):13-17)
[2]卢良玉,徐心同.金县短水准预报效能的研究[J].东北地震研究,1992,8(3):15-27(Lu Liangyu,Xu Xintong.Study of Prediction Efficacy of Leveling at Jinxian[J].Northeastern Seismological Research,1992,8(3):15-27)
[3]苏琴,杨永林,郑兵,等.4.20芦山7.0级地震预测思路及过程回顾[J].地震地质,2014,36(4):1 077-1 093(Su Qin,Yang Yonglin,Zheng Bing,et al.A Review of the Thinking and Process about Prediction of Lushan M7.0Earthquake on Apr.20,2013[J].Seismology and Geology,2014,36(4):1 077-1 093)
[4]王启梁,曹新菊,马敏.红河断裂带的近代形变特征[J].地壳形变与地震,1989,9(1):1-12(Wang Qiliang,Cao Xinju,Ma Min.Faults of the Recent Crustal Deformation on the Red-River Fault Zone[J].Crustal Deformation and Earthquake,1989,9(1):1-12)
[5]虢顺民,张靖,李祥根,等.云南红河断裂带北段断裂位错与地震重复发生的时间间隔[J].地震地质,1984,6(1):1-12(Guo Shunmin,Zhang Jing,Li Xianggen,et al.Fault Displacement and Recurrence Intervals of Earthquakes at the Northern Segment of the Honghe Fault Zone,Yunnan Province[J].Seismology and Geology,1984,6(1):1-12)
[6]刘强,陈燕,王永安.云南断层形变强震异常特征[J].地震研究,2010,33(4):301-307(Liu Qiang,Chen Yan,Wang Yongan.Anomaly of Fault Deformation and Characteristics of Strong Earthquakes in Yunnan Region[J].Journal of Seismological Research,2010,33(4):301-307)
[7]薄万举,华彩虹.地形变强震前兆指标探讨[J].地震,2001,21(1):25-31(Bo Wanju,Hua Caihong.Exploration of the Index of Crustal Deformation Precursor of Strong Earthquakes[J].Earthquake,2001,21(1):25-31)
[8]薄万举.形变异常与干扰关系的再认识[J].大地测量与地球动力学,2010,30(1):5-8(Bo Wanju.Study on Relation between Crust Deformation Anomaly and Disturbances[J].Journal of Geodesy and Geodynamics,2010,30(1):5-8)
[9]陈长云,郑智江,李腊月,等.南北地震带中南段典型强震震前跨断层形变特征分析[J].地震,2016,36(4):47-60(Chen Changyun,Zheng Zhijiang,Li Layue,et al.Abnormal Characteristics of Cross-Fault Observation in the Southern Segment of the North-South Seismic Belt[J].Earthquake,2016,36(4):47-60)
[10]李忠华,苏有锦,刘祖荫.丽江7.0级地震滇西实验场区跨断层短基线短水准测量的变化特征[J].中国地震,1998,14(2):140-149(Li Zhonghua,Su Youjin,Liu Zuyin.Characters of the Variation of Cross Fault Short-Baseline and Short-Range Leveling in Western Yunnan Earthquake Test Site before Lijiang Earthquake(M=7.0)[J].Earthquake Research in China,1998,14(2):140-149)
[11]薄万举,谢觉民,郭良迁.八宝山断裂带形变分析与探讨[J].地震,1998,18(1):63-68(Bo Wanju,Xie Juemin,Guo Liangqian.Analysis and Exploration of Deformation of Babaoshan[J].Earthquake,1998,18(1):63-68)
[12]张兴华,李珊,宋金玲.用断层形变资料探讨滇西实验场区现今构造活动[J].地震研究,1994,17(4):362-369(Zhang Xinghua,Li Shan,Song Jinling.Exploration of Modern Tectonic Movement in WYEPSA by Data of Fault Deformation[J].Journal of Seismological Research,1994,17(4):362-369)
[13]徐锡伟,闻学则,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学D辑:地球科学,2003,33(增1):151-162(Xu Xiwei,Wen Xueze,Zheng Rongzhang,et al.The Latest Tectonic Variation of the Active Block in Sichuan-Yunnan Area and Its Power Source[J].Science in China Series D:Earth Sciences,2003,33(S1):151-162)
[14]李淑玲.山西跨断层形变测量场地布设分析[J].山西地震,1994(3):13-17(Li Shuling.Analysis of the Site Layout of the Across-Fault Deformation Measurement in Shanxi Province[J].Earthquake Research in Shanxi,1994(3):13-17)