2001年施甸M_S5.9地震序列的震源参数研究
|
摘要
以昆明数字地震台网对2001年4月12日施甸MS5.9地震序列观测的近300次地震事件的波形数据资料为基础,用横波波谱资料估算了该次地震序列的震源参数.结果表明,震级在1.5～5.3的范围内,地震矩范围为1010～1016N·m,拐角频率的范围为0.2～8.0Hz,震源破裂半径a的范围为200～2500m,地震应力降的范围为0.1×105～20×105Pa.通过对地震震源拐角频率fc及地震应力降Δσ随时间变化的统计分析,本文研究结果发现,施甸5.9级主震前的前震序列地震的平均拐角频率明显低于主震后余震序列的平均拐角频率.与之相反,地震平均应力降Δσ则是前震序列明显高于余震序列.分析认为,主震前后平均拐角频率和应力降的这种随时间变化特征,具有强震前的前兆信息指示意义.主震的前震序列具有高应力降显示出主震区储存了较高的剪应力;主震后,由于释放了绝大部分应力,余震序列则表现为低应力破裂过程.
On the basis of about 300 earthquake wave forms observed in the Shidian M_S=5.9 sequences on April 12, 2001 recorded in Kunming Digital Seismic Network, the spectra of shear wave have been used to estimate the focal parameters of these earthquake sequences. The results show that within the magnitude range of 1.5~5.3, the seismic moments are 10 10~10 16 N·m, the corner frequencies are 0.2~0.8 Hz, radii of the focal rupture are 200~2 500 m and the stress drops are 0.1×105~20×105 Pa. Through the statistical analyses of variation of corner frequency f_c and stress drop Δσ with time, it is discovered that the average corner frequency of the foreshock sequences is obviously lower than that of the aftershock sequences. Contrary, the average stress drops Δσ of the foreshock sequences are clearly higher than that of the aftershocks. It is considered that these variation characteristics of average corner frequency and stress drops before and after the main shock have index significance to the precursory information before a strong earthquake. The higher stress drops for the foreshock sequences show that the higher shear stresses have been stored in the area of main shock. After the main shock, most of the stresses have been released, so the aftershock sequences show a rupture process of lower stresses.
On the basis of about 300 earthquake wave forms observed in the Shidian M_S=5.9 sequences on April 12, 2001 recorded in Kunming Digital Seismic Network, the spectra of shear wave have been used to estimate the focal parameters of these earthquake sequences. The results show that within the magnitude range of 1.5~5.3, the seismic moments are 10 10~10 16 N·m, the corner frequencies are 0.2~0.8 Hz, radii of the focal rupture are 200~2 500 m and the stress drops are 0.1×105~20×105 Pa. Through the statistical analyses of variation of corner frequency f_c and stress drop Δσ with time, it is discovered that the average corner frequency of the foreshock sequences is obviously lower than that of the aftershock sequences. Contrary, the average stress drops Δσ of the foreshock sequences are clearly higher than that of the aftershocks. It is considered that these variation characteristics of average corner frequency and stress drops before and after the main shock have index significance to the precursory information before a strong earthquake. The higher stress drops for the foreshock sequences show that the higher shear stresses have been stored in the area of main shock. After the main shock, most of the stresses have been released, so the aftershock sequences show a rupture process of lower stresses.
引文
秦嘉政,李宁,胡克坚.1987.1985年云南禄劝地震余震尾波Q值的某些研究[J].地震学报,9(3):239～252
秦嘉政,叶建庆,钱晓东.2003.2000年云南姚安地震的震源参数[J].地球物理学报,46(4):633～641
秦嘉政,谢庆茵,钱晓东.1999.武定地震序列的震源参数与频度特征[J].地震地磁观测与研究,20(3):13～17
肖蔚文.1990.1982年卢龙地震前后的小震震源参数[J].地震学报,12(1):1～11
许向彤,陈运泰,王培德.1999.1995年7月20日怀来盆地ML=4.1地震的破裂过程[J].地震学报,21(6):570～582
叶建庆,苏有锦,刘学军.2003.2001年中强地震序列的震源参数[J].地震研究,25(2):115～123
于湘伟,陈运泰,王培德.1997.京西北延庆-怀来盆地的QSH值和小震震源参数的测定[J].地震地磁观测与研究,18(6):6～8
张天中,马云生,黄蓉良,等.2000.1995年陡河地震前后小震震源参数及其相互关系[J].地震学报,22(3):233～240
周仕勇,许忠淮.2000.由震源谱推断1997年新疆伽师强震群破裂特性[J].地震学报,22(2):113～124
AkiK,RichardsPG.1980.QuantitativeSeismology.TheoryandMethods[M].SanFrancisco:W.H.Freemanand Company,Vol.2,932AkiK.1967.Scalinglawofseismicspectrum[J].JGeophysRes,72:1217～1231
BruneJN.1970.Tectonicstressandspetraofseismicshearwavefromearthquake[J].JGeophysRes,75(4):4997～5009
BruneJN,FletcherJ,WernorF,etal著.吴宁远,程德利,陈步云,等译.1991.根据加利福尼亚安扎数字化遥测台震的新资料得到的低应力降地震[A].见:DasS,DoatWright,ScholzCH,编.地震震源力学[C].北京:地震出版社,226～236
DasS,KostrovBV著.吴宁远,程德利,陈步云,等译.1991.有限断层上的单个凹凸体的破裂—“弱地震”的一种模式?[A].见:DasS,DoatWright,ScholzCH,编.地震震源力学[C].北京:地震出版社,94～100
FletcherJB,HaarLC,VernorFL,etal著.吴宁远,程德利,陈步云,等译.1991.衰减对定标加利福尼亚安扎地区震源参数的影响[A].见:DasS,DoatWright,ScholzCH,编.地震震源力学[C].北京:地震出版社,323～330
JonesLE,HelmbergerDV.1998.EarthquakesourceparametersandfaultkinematicintheeasternCaliforniashearzone[J].BullSeismSocAmer,88(6):1337～1352
MandalP,RastogiBK,SarmaCSP.1998.SourceparametersofKoynaearthquakeIndia[J].BullSeismSocAmer,88(3):833～842
秦嘉政,叶建庆,钱晓东.2003.2000年云南姚安地震的震源参数[J].地球物理学报,46(4):633～641
秦嘉政,谢庆茵,钱晓东.1999.武定地震序列的震源参数与频度特征[J].地震地磁观测与研究,20(3):13～17
肖蔚文.1990.1982年卢龙地震前后的小震震源参数[J].地震学报,12(1):1～11
许向彤,陈运泰,王培德.1999.1995年7月20日怀来盆地ML=4.1地震的破裂过程[J].地震学报,21(6):570～582
叶建庆,苏有锦,刘学军.2003.2001年中强地震序列的震源参数[J].地震研究,25(2):115～123
于湘伟,陈运泰,王培德.1997.京西北延庆-怀来盆地的QSH值和小震震源参数的测定[J].地震地磁观测与研究,18(6):6～8
张天中,马云生,黄蓉良,等.2000.1995年陡河地震前后小震震源参数及其相互关系[J].地震学报,22(3):233～240
周仕勇,许忠淮.2000.由震源谱推断1997年新疆伽师强震群破裂特性[J].地震学报,22(2):113～124
AkiK,RichardsPG.1980.QuantitativeSeismology.TheoryandMethods[M].SanFrancisco:W.H.Freemanand Company,Vol.2,932AkiK.1967.Scalinglawofseismicspectrum[J].JGeophysRes,72:1217～1231
BruneJN.1970.Tectonicstressandspetraofseismicshearwavefromearthquake[J].JGeophysRes,75(4):4997～5009
BruneJN,FletcherJ,WernorF,etal著.吴宁远,程德利,陈步云,等译.1991.根据加利福尼亚安扎数字化遥测台震的新资料得到的低应力降地震[A].见:DasS,DoatWright,ScholzCH,编.地震震源力学[C].北京:地震出版社,226～236
DasS,KostrovBV著.吴宁远,程德利,陈步云,等译.1991.有限断层上的单个凹凸体的破裂—“弱地震”的一种模式?[A].见:DasS,DoatWright,ScholzCH,编.地震震源力学[C].北京:地震出版社,94～100
FletcherJB,HaarLC,VernorFL,etal著.吴宁远,程德利,陈步云,等译.1991.衰减对定标加利福尼亚安扎地区震源参数的影响[A].见:DasS,DoatWright,ScholzCH,编.地震震源力学[C].北京:地震出版社,323～330
JonesLE,HelmbergerDV.1998.EarthquakesourceparametersandfaultkinematicintheeasternCaliforniashearzone[J].BullSeismSocAmer,88(6):1337～1352
MandalP,RastogiBK,SarmaCSP.1998.SourceparametersofKoynaearthquakeIndia[J].BullSeismSocAmer,88(3):833～842
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心