YRY-4型钻孔应变仪观测的P波剪应变
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摘要
传统地震仪观测的是一个点的位移随时间的变化,而应变仪观测的是位移的空间导数随时间的变化。在四川姑咱台用YRY-4型四分量钻孔应变仪进行的每秒100次采样观测实验,记录到三次地方震。在这样高的采样率下,YRY-4型四分量应变仪观测数据保持了令人满意的自洽和足够高的信度。观测表明,P波的应变不仅有面应变成分,而且有剪应变成分。这为澄清P波的性质,给出了直接的观测证据。根据弹性波理论,P波无旋转,可以有体应变和剪应变成分。
While a traditional seismograph records the variations of displacement with time at a point,a tensor strainmeter monitors the variations of the spacial gradient of displacement.An YRY-4 borehole strainmeter at Guza,Sichuan province,recorded three local seismic events at the sampling rate of 100sps for the first time.At this high sampling rate,the data of the YRY-4 demonstrated a satisfying degree of self-consistency and sufficiently high credibility.The observation shows that P wave strain contains areal strain components as well as shear strain component.It gives direct evidence for the property of P wave.According to the theory of seismology,P wave is clarified to have no rotation,but it has volumetric strain and shear strains.
While a traditional seismograph records the variations of displacement with time at a point,a tensor strainmeter monitors the variations of the spacial gradient of displacement.An YRY-4 borehole strainmeter at Guza,Sichuan province,recorded three local seismic events at the sampling rate of 100sps for the first time.At this high sampling rate,the data of the YRY-4 demonstrated a satisfying degree of self-consistency and sufficiently high credibility.The observation shows that P wave strain contains areal strain components as well as shear strain component.It gives direct evidence for the property of P wave.According to the theory of seismology,P wave is clarified to have no rotation,but it has volumetric strain and shear strains.
引文
[1]潘立宙.与地应力测量有关的几个公式的推导和讨论[A].中国地质科学院地质力学研究所和国家地震局地震地质大队编.地应力测量的原理和应用[C].北京:地质出版社,1981.163-203.
[2]Gladwin M T,Hart R.Design parameters for borehole strain instrumentation[J].Pure Appl Geo-phys,1985,123:59-80.
[3]邱泽华,石耀霖,欧阳祖熙.四分量钻孔应变观测的实地绝对标定[J].地震,2005,25(3):27-34.
[4]Benioff H,F Press,Smith S.Excitation of the free oscillations of the Earth by earthquakes[J].JGeophys Res,1961,66(2):605-619.
[5]池顺良,武红岭,骆鸣津.钻孔应变观测中潮汐因子离散性与各向异性原因探讨——“十五”数字地震观测网络分量钻孔应变仪首批观测资料分析解释[J].地球物理学进展,2007,22(6):1 746-1 753.
[6]郭燕平,邱泽华,李素华,等.钻孔体应变高采样率观测实验[J].大地测量与地球动力学,2012,32(1):51-55.
[7]杨选辉,杨树新,张彬,等.测震数采仪记录的钻孔应变[J].中国地震,2011,27(1):65-71.
[8]邱泽华,石耀霖,欧阳祖熙.四分量钻孔观测的实地相对标定[J].大地测量与地球动力学,2005,25(1):118-122.
[9]邱泽华,阚宝祥,唐磊.四分量钻孔应变观测资料的换算和使用[J].地震,2009,29(4):83-89.
[10]Qiu Z,Tang L,Zhang B,et al.In situ calibration of and algorithm for strain monitoring using four-gauge borehole strainmeters(FGBS)[J].J Geophys Res Solid Earth,2013,118,doi:10.1002/jgrb.50112.
[11]钱伟长,叶开沅.弹性力学[M].北京:科学出版社,1956.
[12]Bullen K E.An Introduction to the Theory of Seismology[M].Camb.Univ.Press,Cambridge,3rded,1963.
[2]Gladwin M T,Hart R.Design parameters for borehole strain instrumentation[J].Pure Appl Geo-phys,1985,123:59-80.
[3]邱泽华,石耀霖,欧阳祖熙.四分量钻孔应变观测的实地绝对标定[J].地震,2005,25(3):27-34.
[4]Benioff H,F Press,Smith S.Excitation of the free oscillations of the Earth by earthquakes[J].JGeophys Res,1961,66(2):605-619.
[5]池顺良,武红岭,骆鸣津.钻孔应变观测中潮汐因子离散性与各向异性原因探讨——“十五”数字地震观测网络分量钻孔应变仪首批观测资料分析解释[J].地球物理学进展,2007,22(6):1 746-1 753.
[6]郭燕平,邱泽华,李素华,等.钻孔体应变高采样率观测实验[J].大地测量与地球动力学,2012,32(1):51-55.
[7]杨选辉,杨树新,张彬,等.测震数采仪记录的钻孔应变[J].中国地震,2011,27(1):65-71.
[8]邱泽华,石耀霖,欧阳祖熙.四分量钻孔观测的实地相对标定[J].大地测量与地球动力学,2005,25(1):118-122.
[9]邱泽华,阚宝祥,唐磊.四分量钻孔应变观测资料的换算和使用[J].地震,2009,29(4):83-89.
[10]Qiu Z,Tang L,Zhang B,et al.In situ calibration of and algorithm for strain monitoring using four-gauge borehole strainmeters(FGBS)[J].J Geophys Res Solid Earth,2013,118,doi:10.1002/jgrb.50112.
[11]钱伟长,叶开沅.弹性力学[M].北京:科学出版社,1956.
[12]Bullen K E.An Introduction to the Theory of Seismology[M].Camb.Univ.Press,Cambridge,3rded,1963.
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