JCZ-1型地震仪观测的地球环型自由振荡
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摘要
本文首次采用JCZ-1型地震仪观测资料研究地球环型自由振荡,并在2011年日本9.0级地震、2010年智利8.8级地震和2005年印尼8.6级地震后武汉地震台JCZ-1型地震仪观测到了其激发的环型自由振荡,从中检测了基振型0T2～0T67和一次振型1T2～1T50等振型的本征周期,与PREM的理论值比较,误差比小于0.5%,补充了PREM中未提到的几次振型的本征周期:0T11、0T15、0T19、1T4、1T5、1T14,并观测到了日本地震0T2、0T6、0T7和0T8振型的多峰值现象。研究结果表明,JCZ-1型地震仪具有良好的观测超低频长周期地球自由振荡的能力。
We first studied Earth′s free torsional oscillation using observed data of JCZ-1 seismometer.JCZ-1 seismometer at the Wuhan Observation Station has observed the Earth′s free oscillations excited by the great 2011 Japan earthquake,the great 2010 Chile earthquake and the great 2005 Indonesia earthquake,we detected the eigen periods of basic and first mode: 0 T2~0 T67 and 1 T2~1 T50,and error ratio is less than 0.5% by comparing with the PREM theoretical eigenvalues.We also complemented some modes: 0 T11,0 T15,0 T19,1 T4,1 T5,1 T14,which are not mentioned in PREM,and observed the multi-peak phenomenon of 0 T2,0 T6,0 T7 和0 T8.The results show that JCZ-1 seismometer can precisely observe ultralow frequency and long period free oscillations of the Earth.
We first studied Earth′s free torsional oscillation using observed data of JCZ-1 seismometer.JCZ-1 seismometer at the Wuhan Observation Station has observed the Earth′s free oscillations excited by the great 2011 Japan earthquake,the great 2010 Chile earthquake and the great 2005 Indonesia earthquake,we detected the eigen periods of basic and first mode: 0 T2~0 T67 and 1 T2~1 T50,and error ratio is less than 0.5% by comparing with the PREM theoretical eigenvalues.We also complemented some modes: 0 T11,0 T15,0 T19,1 T4,1 T5,1 T14,which are not mentioned in PREM,and observed the multi-peak phenomenon of 0 T2,0 T6,0 T7 和0 T8.The results show that JCZ-1 seismometer can precisely observe ultralow frequency and long period free oscillations of the Earth.
引文
[1]曾融生.固体地球物理学导论[M].北京:科学出版社,1984.115-123.
[2]Dziewonski A M,Anderson D L.Preliminary reference earth model[J].Phy Earth Planet Int,1981,25:297-356.
[3]Haddon R A W,Bullen K E.An earth model incorporating free oscillation data[J].Phys EarthPlanet Interi,1969,2:35-49.
[4]Resovsky J,SRitzwoller M H.A degree 8mantles hear velocity model from normal mode observa-tions below 3mHz[J].J Geophys Res,1999,104:993-1 014.
[5]Lamb H.On the variations of an elastic sphere[J].Lond Math Soc Proc,1882,13:233-256.
[6]Love A E H.Some problem of Geodynamics[M].London:Cambridge University Press,1911.176-181.
[7]Benioff H,Press F,Smith S.Excitation of the free oscillation of the Earth by earthquakes[J].JGeophys Res,1961,66(2):605-619.
[8]Alsop L E,Sutton G H,Ewing M.Free oscillations of the Earth observed on strain and pendulumseismographs[J].J geophys Res,1961,66(2):631-641.
[9]Alsop L E.Free spheroidal vibration of the Earth at very long periods[J].Bull Seism Soc of Am,1963,53(3):483-501.
[10]方俊.地球自由振荡[J].测量与地球物理集刊,1986,(7):65-68.
[11]杨兆,孙和平,雷湘鄂.环型自由振荡简正模的计算[J].大地测量与地球动力学,2007,27(4):38-43.
[12]吕永清,蔡亚先,周云耀.用JCZ-1超宽频带地震仪观测地球自由振荡[J].地壳形变与地震,1997,17(3):103-105.
[13]雷湘鄂,许厚泽,孙和平.利用超导重力观测资料检测地球自由振荡[J].科学通报,2002,47(18):1 432-1 436.
[14]万永革,周公威,郭燕平.中国数字地震台网记录的昆仑山口西地震的球型自由振荡[J].地震,2005,25(1):31-39.
[15]于海英,朱元清,寿海涛.印度洋9.0级大地震激发的球型振荡和环型振荡[J].地球物理学进展,2006,21(3):706-716.
[16]邱泽华,马瑾,池顺良,等.钻孔差应变仪观测的苏门答腊大地震激发的地球环型自由振荡[J].地球物理学报,2007,50(3):797-805.
[17]蔡亚先,吕永清,周云耀,等.JCZ-1超宽频带地震计[J].地壳形变与地震,1995,15(3):1-8.
[18]傅淑芳,刘宝诚,李文艺.地震学教程[M].北京:地震出版社,1980.310-332.
[19]T G Masters,R Widmer.Free oscillations:Frequencies and Attenuations.Global earth physics:ahandbook of physical constants[M].Washing D C:the American Geophysical Union,1995.104-125.
[20]Geller R J,Stein S.Split free oscillation amplitudes for the 1960Chilean and 1964Alaskan earth-quakes[J].Bull Seism Soc Amer,1977,67(3):651-660.
[21]Dahlen F A,Sailor R V.Rotational and elliptical splitting of the free oscillations of the earth[J].Geophys J R astr Soc,1979,58:609-623.
[22]万永革,盛书中,周公威,等.中国数字地震台网记录的苏门答腊—安达曼地震激发的地球球型自由振荡的检测[J].地震学报,2007,29(4):369-381.
[23]雷湘鄂,许厚泽,孙和平.由5个国际超导重力仪台站资料检测到的秘鲁8.2级大地震所激发的球型自由振荡现象[J].中国科学(D辑),2004,34(5):483-491.
[24]Masters G,Gilbert F.Structure of the inner core inferred from observations of its spheroidal shearmodes[J].Geophys Res Lett,1981,8:569-571.
[25]Morrelli A,Dziewonski A M,Woodhouse J H.Anisotropy of inner core inferred from PKIKP traveltimes[J].Geophys Res Lett,1986,13:1 545-1 548.
[26]Song X D,Helmberger D V.Depth dependence of anisotropy of the Earth′s inner core[J].J Geo-phys Res,1995,100:9 805-9 816.
[27]Durek J J,Romanowicz B.Inner core an isotropy inferred by direct in version of normal model spec-tra[J].Geophys J Int,1999,139:599-622.
[2]Dziewonski A M,Anderson D L.Preliminary reference earth model[J].Phy Earth Planet Int,1981,25:297-356.
[3]Haddon R A W,Bullen K E.An earth model incorporating free oscillation data[J].Phys EarthPlanet Interi,1969,2:35-49.
[4]Resovsky J,SRitzwoller M H.A degree 8mantles hear velocity model from normal mode observa-tions below 3mHz[J].J Geophys Res,1999,104:993-1 014.
[5]Lamb H.On the variations of an elastic sphere[J].Lond Math Soc Proc,1882,13:233-256.
[6]Love A E H.Some problem of Geodynamics[M].London:Cambridge University Press,1911.176-181.
[7]Benioff H,Press F,Smith S.Excitation of the free oscillation of the Earth by earthquakes[J].JGeophys Res,1961,66(2):605-619.
[8]Alsop L E,Sutton G H,Ewing M.Free oscillations of the Earth observed on strain and pendulumseismographs[J].J geophys Res,1961,66(2):631-641.
[9]Alsop L E.Free spheroidal vibration of the Earth at very long periods[J].Bull Seism Soc of Am,1963,53(3):483-501.
[10]方俊.地球自由振荡[J].测量与地球物理集刊,1986,(7):65-68.
[11]杨兆,孙和平,雷湘鄂.环型自由振荡简正模的计算[J].大地测量与地球动力学,2007,27(4):38-43.
[12]吕永清,蔡亚先,周云耀.用JCZ-1超宽频带地震仪观测地球自由振荡[J].地壳形变与地震,1997,17(3):103-105.
[13]雷湘鄂,许厚泽,孙和平.利用超导重力观测资料检测地球自由振荡[J].科学通报,2002,47(18):1 432-1 436.
[14]万永革,周公威,郭燕平.中国数字地震台网记录的昆仑山口西地震的球型自由振荡[J].地震,2005,25(1):31-39.
[15]于海英,朱元清,寿海涛.印度洋9.0级大地震激发的球型振荡和环型振荡[J].地球物理学进展,2006,21(3):706-716.
[16]邱泽华,马瑾,池顺良,等.钻孔差应变仪观测的苏门答腊大地震激发的地球环型自由振荡[J].地球物理学报,2007,50(3):797-805.
[17]蔡亚先,吕永清,周云耀,等.JCZ-1超宽频带地震计[J].地壳形变与地震,1995,15(3):1-8.
[18]傅淑芳,刘宝诚,李文艺.地震学教程[M].北京:地震出版社,1980.310-332.
[19]T G Masters,R Widmer.Free oscillations:Frequencies and Attenuations.Global earth physics:ahandbook of physical constants[M].Washing D C:the American Geophysical Union,1995.104-125.
[20]Geller R J,Stein S.Split free oscillation amplitudes for the 1960Chilean and 1964Alaskan earth-quakes[J].Bull Seism Soc Amer,1977,67(3):651-660.
[21]Dahlen F A,Sailor R V.Rotational and elliptical splitting of the free oscillations of the earth[J].Geophys J R astr Soc,1979,58:609-623.
[22]万永革,盛书中,周公威,等.中国数字地震台网记录的苏门答腊—安达曼地震激发的地球球型自由振荡的检测[J].地震学报,2007,29(4):369-381.
[23]雷湘鄂,许厚泽,孙和平.由5个国际超导重力仪台站资料检测到的秘鲁8.2级大地震所激发的球型自由振荡现象[J].中国科学(D辑),2004,34(5):483-491.
[24]Masters G,Gilbert F.Structure of the inner core inferred from observations of its spheroidal shearmodes[J].Geophys Res Lett,1981,8:569-571.
[25]Morrelli A,Dziewonski A M,Woodhouse J H.Anisotropy of inner core inferred from PKIKP traveltimes[J].Geophys Res Lett,1986,13:1 545-1 548.
[26]Song X D,Helmberger D V.Depth dependence of anisotropy of the Earth′s inner core[J].J Geo-phys Res,1995,100:9 805-9 816.
[27]Durek J J,Romanowicz B.Inner core an isotropy inferred by direct in version of normal model spec-tra[J].Geophys J Int,1999,139:599-622.
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