赣中西地区地震波谱分析
|
摘要
选取赣中西地区23个ML≥2.0地震的单台波形数据,基于遗传算法,分别采用ω-3和ω-2震源谱模型对每个地震每个水平向的振幅谱进行搜索,得到2组低频水平Ω0和拐角频率fc。目测发现大多数地震震源谱符合ω-3模型,除1个地震的fc接近6 Hz外,其余22个地震的fc均小于3.51 Hz,明显偏低。这23个地震除fc接近6 Hz的这个地震没有出现短周期面波外,其余22个地震短周期面波均比较发育。认为可能是这些地震震源浅造成P、S相干后形成了瑞利型短周期面波造成它们的拐角频率偏低。
Based on the digital data of 23 earthquakes with ML≥2.0 in the central and western Jiangxi,we obtained 23 pairs of lower frequency level limit(Ω0)and corner frequencies(fc) by source spectrum models of ω-3 and ω-2,and the genetic algorithm.Comparing with the two source spectra of ω-3 and ω-2 for every earthquake,we find that most of these source spectra are consistant with the ω-3 attenuation model.Their values of fc are less than 3.51Hz.Correspondingly with obvious short-period surface wave.Only one earthquake shows no short-period surface wave with the value of fc of which is about 6 Hz.We believe that the lower corner frequencies are probably resulted from interferences of P wave and S wave radiated from shallow sources.
Based on the digital data of 23 earthquakes with ML≥2.0 in the central and western Jiangxi,we obtained 23 pairs of lower frequency level limit(Ω0)and corner frequencies(fc) by source spectrum models of ω-3 and ω-2,and the genetic algorithm.Comparing with the two source spectra of ω-3 and ω-2 for every earthquake,we find that most of these source spectra are consistant with the ω-3 attenuation model.Their values of fc are less than 3.51Hz.Correspondingly with obvious short-period surface wave.Only one earthquake shows no short-period surface wave with the value of fc of which is about 6 Hz.We believe that the lower corner frequencies are probably resulted from interferences of P wave and S wave radiated from shallow sources.
引文
[1]刘细元,马振兴,杨永革,等.宜春-新余一带岩溶基本特征及发育规律分析[J].东华理工学院学报,2006,29(2):127-132.
[2]Atkinson G M,Mereu R F.The shape of ground motion attenuation curves in southeastern Canada[J].BullSeism Soc Amer,1992,82:2014-2031.
[3]黄玉龙,郑斯华,刘杰,等.广东地区地震波衰减和场地响应的研究[J].地球物理学报,2003,46(1):54-61.
[4]刘杰,郑斯华,黄玉龙.利用遗传算法反演非弹性衰减系数、震源参数和场地响应[J].地震学报,2003,25(2):211-218.
[5]Aki K,Chouet B.Origin of coda waves:source,attenuation and scattering effects[J].J.G.R.,1975,80:3322-3342.
[6]孙勇,郑斯华.利用数字化地震记录进行震源参数和介质衰减系数的联合反演[J].东北地震研究,1995,11(2):1-13.
[7]Brune J.N..Tectonic stress and the spectrum of seismic shear waves from earthquakes[J].J.G.R.,1970,75(26):4997-5009.
[8]Brune J.N..Correction[J].J.G.R.,1971,76(20):5002.
[9]Savage J.C..Relation of corner frequeney to fault dimensions[J].J.G.R.,1972,77(20):3788-3795.
[10]陈运泰,吴忠良,王培德,等.数字地震学[M].北京:地震出版社,2000.
[11]康英,郑斯华,刘杰,等.中小地震震源参数的求解及其相似关系[J].华南地震,2004,24(2):11-21
[12]王卫东,张永志,狄秀玲,等.陕西省关中及邻区地震的震源参数研究[J].地震研究,2004,27(4):330-333.
[2]Atkinson G M,Mereu R F.The shape of ground motion attenuation curves in southeastern Canada[J].BullSeism Soc Amer,1992,82:2014-2031.
[3]黄玉龙,郑斯华,刘杰,等.广东地区地震波衰减和场地响应的研究[J].地球物理学报,2003,46(1):54-61.
[4]刘杰,郑斯华,黄玉龙.利用遗传算法反演非弹性衰减系数、震源参数和场地响应[J].地震学报,2003,25(2):211-218.
[5]Aki K,Chouet B.Origin of coda waves:source,attenuation and scattering effects[J].J.G.R.,1975,80:3322-3342.
[6]孙勇,郑斯华.利用数字化地震记录进行震源参数和介质衰减系数的联合反演[J].东北地震研究,1995,11(2):1-13.
[7]Brune J.N..Tectonic stress and the spectrum of seismic shear waves from earthquakes[J].J.G.R.,1970,75(26):4997-5009.
[8]Brune J.N..Correction[J].J.G.R.,1971,76(20):5002.
[9]Savage J.C..Relation of corner frequeney to fault dimensions[J].J.G.R.,1972,77(20):3788-3795.
[10]陈运泰,吴忠良,王培德,等.数字地震学[M].北京:地震出版社,2000.
[11]康英,郑斯华,刘杰,等.中小地震震源参数的求解及其相似关系[J].华南地震,2004,24(2):11-21
[12]王卫东,张永志,狄秀玲,等.陕西省关中及邻区地震的震源参数研究[J].地震研究,2004,27(4):330-333.
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