长白山天池火山地区的尾波Q值估计
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摘要
对1999～2005年间长白山天池火山观测站所有数字化波形记录中震级ML≥0.6的94个火山地震事件,利用频率在1.0～16.0Hz范围内的记录,依据S波单次反散射模型测算了长白山天池火山区的尾波Q值,获得尾波Q值与频率的关系为QC=(47±2)f(0.74±0.01)。假定衰减完全由散射损失造成,则估计得到长白山天池火山区的最小平均自由程为17km,且与所用的频率无关,表明天池火山区下方散射体分布密度较大。
On the basis of near-field data recorded by the Mt.Changbai Tianchi volcanic station,94 digital local events with M_L≥0.6 during 1999～2005 are selected.Then coda Q_C in the Mt.Changbai Tianchi volcanic region,East China has been determined according to dispersion theory of coda from the decay of the amplitudes of coda wave on narrow band-pass-filtered seismograms of local microearthquakes in a range from 1.0Hz to 16Hz.It has a frequency dependence of the form Q_C=(47±2)f(0.74±0.01),which shows that Mt.Changbai Tianchi volcanic region belongs to unstable tectonic environment.For each frequency band,the coda Q_C values,averaged over all earthquakes.Considering a model incorporating both scattering and intrinsic attenuation,and assuming that the attenuation is entirely due to the scattering loss,a frequency-independent minimum mean free path of about 17km have been obtained,so the density of scatters is large under the Mt.Changbai Tianchi volcanic region.
On the basis of near-field data recorded by the Mt.Changbai Tianchi volcanic station,94 digital local events with M_L≥0.6 during 1999～2005 are selected.Then coda Q_C in the Mt.Changbai Tianchi volcanic region,East China has been determined according to dispersion theory of coda from the decay of the amplitudes of coda wave on narrow band-pass-filtered seismograms of local microearthquakes in a range from 1.0Hz to 16Hz.It has a frequency dependence of the form Q_C=(47±2)f(0.74±0.01),which shows that Mt.Changbai Tianchi volcanic region belongs to unstable tectonic environment.For each frequency band,the coda Q_C values,averaged over all earthquakes.Considering a model incorporating both scattering and intrinsic attenuation,and assuming that the attenuation is entirely due to the scattering loss,a frequency-independent minimum mean free path of about 17km have been obtained,so the density of scatters is large under the Mt.Changbai Tianchi volcanic region.
引文
李白基、秦嘉政、叶建庆等,2000,腾冲火山区剪切波和尾波衰减初步研究,地震研究,23(2),136～142。
李松林、樊计昌、惠乃玲等,1990,滦县地区尾波Q值及其与频率关系的研究,地震学报,12(4),357～366。
汤吉、李国深等,2001,长白山天池火山区电性结构和岩浆系统,地震地质,23(2),191～200。
吴建平、明跃红、刘一鸣等,2003,2002年8月20日长白山天池火山小震震群研究,地震地磁观测与研究,24(4),1～8。
吴建平、明跃红、苏伟,2004,长白山天池火山的深部结构及地震活动特征研究.中国大陆地球深部结构与动力学研究.北京:科学出版社,859～871。
王伟君、刘杰,2004,1999年,岫岩地震序列尾波的QC变化过程,24(4),37～44。
杨卓欣、张先康、赵金仁等,2005,长白山天池火山区三维速度结构层析成像,地球物理学报,48(1),107～115。
曾健,陈天长,韩渭宾,1997,成都遥测台网区域尾波衰减特性及Q值研究,地震学报,19(3),246～253。
曾健、聂永安、1989,单次与多次散射对地方震尾波的作用,地震学报,11(1),12～23。
张成科、张先康,2002,长白山天池火山区及邻近地区壳幔结构探测研究,地球物理学报,45(6),812～820。
张天中、高龙生、张卫平,1990,滇西试验场区的Q值及其随时间窗的变化,地震学报,12(1),12～21。
Aki,K,1969,Analysis of the seismic coda of local earthquake as scattered waves.J.Geophys.Res,74,615～631.
Aki,K,1980a,Attentuation of shear wavesinthelithosphereforfrequenciesfrom0.05to25Hz.Phys.Earth Planet.Interiors,21,50～60.
Aki,K,1980b,Scattering and attenuation of shear waves inthe lithosphere.J.Geophys.Res,85,6496～6504.
Aki,K,Chouet,B,1975,Origin of coda waves:source,attenuation and scattering effects.J.Geophys.Res,80,3322～3342.
Ambeh and Fairhead,1989,CodaQestimates inthe Mount Cameroon Volcanic region,west Africa.BSSA,79(5),1589～1600.
ChouetB,1976,Sourcescattering and attenuation effects on high frequency seismic waves,Ph.D.Thesis,Massachusetts Institute ofTechnology,Cambridge,Massachusetts.
Danty,A.M1981,Ascattering model to explain seismicQobservations in the lithosphere between1and30Hz.Geophys.Res.Lett,8,1126～1128.
Del Pezzo,et al,1985,QCobservations inthe lithosphere between1～30Hz,Geophys.Res.Lett.8,1126～1128.
Fehler M,Roberts P,Fairbanks T,1988,Atemporal change in coda wave attenuation observed during an eruption of Mount St,Helens.J.Geophys.Res,93,4367～4373.
Frankel,A.,Wennerberg,1987,Energy-flux model of seismic coda:separation of scattering and intrinsic attenuation.Bull.Seism.Soc.Am,77,1223～1251.
Pulli,J.J.,1984Attenuation of coda waves in NewEngland.Bull.Seism.Soc.Am,74,1149～1166.
Singh S,Herrmann R B,1983,Regionalization of crustal codaQinthe continental United States.J.Geophys.Res,88,527～538.
Rautian,T.G.et al1978,The use of the coda for the determination of the earthquake source spectrum.Bull.Seism.Soc.Am,68,923～943.
Rebollar,C.J.,et al1985,Estimates of seismic wave attenuationin northern Baja,S.California.Bull.Seism.Soc.Am,75,1371～1382.
Roecker,S.W.,Tucker,et al,1982,Estimates ofQincentral Asia as afunctionof frequencyand depth usingthe coda of locallyrecordedearthquakes.Bull.Seism.Soc.Am,72,129～149.
Van Eck,T.,1988,Attenuation of coda waves inthe Dead Sea Region,Bull.Seism.Soc.Am,78,770～779.
李松林、樊计昌、惠乃玲等,1990,滦县地区尾波Q值及其与频率关系的研究,地震学报,12(4),357～366。
汤吉、李国深等,2001,长白山天池火山区电性结构和岩浆系统,地震地质,23(2),191～200。
吴建平、明跃红、刘一鸣等,2003,2002年8月20日长白山天池火山小震震群研究,地震地磁观测与研究,24(4),1～8。
吴建平、明跃红、苏伟,2004,长白山天池火山的深部结构及地震活动特征研究.中国大陆地球深部结构与动力学研究.北京:科学出版社,859～871。
王伟君、刘杰,2004,1999年,岫岩地震序列尾波的QC变化过程,24(4),37～44。
杨卓欣、张先康、赵金仁等,2005,长白山天池火山区三维速度结构层析成像,地球物理学报,48(1),107～115。
曾健,陈天长,韩渭宾,1997,成都遥测台网区域尾波衰减特性及Q值研究,地震学报,19(3),246～253。
曾健、聂永安、1989,单次与多次散射对地方震尾波的作用,地震学报,11(1),12～23。
张成科、张先康,2002,长白山天池火山区及邻近地区壳幔结构探测研究,地球物理学报,45(6),812～820。
张天中、高龙生、张卫平,1990,滇西试验场区的Q值及其随时间窗的变化,地震学报,12(1),12～21。
Aki,K,1969,Analysis of the seismic coda of local earthquake as scattered waves.J.Geophys.Res,74,615～631.
Aki,K,1980a,Attentuation of shear wavesinthelithosphereforfrequenciesfrom0.05to25Hz.Phys.Earth Planet.Interiors,21,50～60.
Aki,K,1980b,Scattering and attenuation of shear waves inthe lithosphere.J.Geophys.Res,85,6496～6504.
Aki,K,Chouet,B,1975,Origin of coda waves:source,attenuation and scattering effects.J.Geophys.Res,80,3322～3342.
Ambeh and Fairhead,1989,CodaQestimates inthe Mount Cameroon Volcanic region,west Africa.BSSA,79(5),1589～1600.
ChouetB,1976,Sourcescattering and attenuation effects on high frequency seismic waves,Ph.D.Thesis,Massachusetts Institute ofTechnology,Cambridge,Massachusetts.
Danty,A.M1981,Ascattering model to explain seismicQobservations in the lithosphere between1and30Hz.Geophys.Res.Lett,8,1126～1128.
Del Pezzo,et al,1985,QCobservations inthe lithosphere between1～30Hz,Geophys.Res.Lett.8,1126～1128.
Fehler M,Roberts P,Fairbanks T,1988,Atemporal change in coda wave attenuation observed during an eruption of Mount St,Helens.J.Geophys.Res,93,4367～4373.
Frankel,A.,Wennerberg,1987,Energy-flux model of seismic coda:separation of scattering and intrinsic attenuation.Bull.Seism.Soc.Am,77,1223～1251.
Pulli,J.J.,1984Attenuation of coda waves in NewEngland.Bull.Seism.Soc.Am,74,1149～1166.
Singh S,Herrmann R B,1983,Regionalization of crustal codaQinthe continental United States.J.Geophys.Res,88,527～538.
Rautian,T.G.et al1978,The use of the coda for the determination of the earthquake source spectrum.Bull.Seism.Soc.Am,68,923～943.
Rebollar,C.J.,et al1985,Estimates of seismic wave attenuationin northern Baja,S.California.Bull.Seism.Soc.Am,75,1371～1382.
Roecker,S.W.,Tucker,et al,1982,Estimates ofQincentral Asia as afunctionof frequencyand depth usingthe coda of locallyrecordedearthquakes.Bull.Seism.Soc.Am,72,129～149.
Van Eck,T.,1988,Attenuation of coda waves inthe Dead Sea Region,Bull.Seism.Soc.Am,78,770～779.
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