汶川地震强余震统计特性及地震动衰减关系
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摘要
2008年"5·12"汶川特大地震发生后,固定及流动台站获得了数量可观的余震地震动数据,为地震危险性分析和地震动衰减规律研究提供了丰富的数据。通过Gutenberg-Richter关系分析得到汶川地震余震震级-频度分布(FMD),结合B?th定律预估得到逼近实际的最大预估余震震级,基于修正的Omori定律拟合得到余震发生率与主震后时间的关系。主余震统计特性显示M_s4.0～6.4范围内的余震记录震中距及震级分布相对均匀,可作为建立地震动衰减规律的依据。故针对土层地表及基岩地表分别进行了EW、NS和UD三个方向的统计回归分析,给出了2种地表情况下三向地震动峰值加速度的定量衰减关系表达式。
After the 2008 devastating Wenchuan Earthquake on May 12 th, a considerable number of aftershock ground motion records were obtained by both the fixed and mobile stations, which provide abundant research data for seismic risk analysis and ground motion attenuation relationship investigation. In this paper, the frequency-magnitude distribution of the aftershocks of the Wenchuan Earthquake was established through the Gutenberg-Richter relation. With the B?th law, the estimated maximum aftershock magnitude was predicted, which is close to the real value. The relationship between the aftershock occurrence rate and the time after the mainshock was fitted based on the modified Omori law. The statistical characteristics show that the distribution of the epicentral distances and the magnitudes of the aftershock records for the magnitudes ranging from 4.0 to 6.4 is relatively even, which can be used for establishing the ground motion attenuation relationships. The statistical regression analyses of the EW, NS, and UD ground motion components were carried out respectively for both the soil and bedrock surfaces, and the quantitative peak ground acceleration(PGA) attenuation relationships for the 3 components were obtained.
After the 2008 devastating Wenchuan Earthquake on May 12 th, a considerable number of aftershock ground motion records were obtained by both the fixed and mobile stations, which provide abundant research data for seismic risk analysis and ground motion attenuation relationship investigation. In this paper, the frequency-magnitude distribution of the aftershocks of the Wenchuan Earthquake was established through the Gutenberg-Richter relation. With the B?th law, the estimated maximum aftershock magnitude was predicted, which is close to the real value. The relationship between the aftershock occurrence rate and the time after the mainshock was fitted based on the modified Omori law. The statistical characteristics show that the distribution of the epicentral distances and the magnitudes of the aftershock records for the magnitudes ranging from 4.0 to 6.4 is relatively even, which can be used for establishing the ground motion attenuation relationships. The statistical regression analyses of the EW, NS, and UD ground motion components were carried out respectively for both the soil and bedrock surfaces, and the quantitative peak ground acceleration(PGA) attenuation relationships for the 3 components were obtained.
引文
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[8] 刘浪.汶川地震地震动衰减特性分析[D].哈尔滨:中国地震局工程力学研究所,2010.LIU Lang.Analysis about characteristics of ground motion attenuation of Wenchuan earthquake [D].Harbin:Institute of Engineering Mechanics,China Earthquake Administration,2010.(in Chinese)
[9] KANAI K,YOSHIZAWA S,SUZUKI T.An empirical formula for the spectrum of strong earthquake motions II [J].东京大学地震研究所汇报,1963,41:261-270.
[10] ESTEVA L.Seismic risk and seismic design decisions // Seismic Design for Nuclear Power Plants.Cambridge,Mass.:Mass.Inst.Technol.,1970.142-182.
[11] MCGUIRE RK.Seismic ground motion parameter relations [J].Journal of the Geotechnical Engineering Division,1978,104(4):481-490.
[2] SHCHERBAKOV R,GODA K,IVANIAN A,et al.Aftershock statistics of major subduction earthquakes [J].Bulletin of the Seismological Society of America,2013,103(6):3222-3234.
[3] RUIZ-GARCíA J.Mainshock-aftershock ground motion features and their influence in building′s seismic response [J].Journal of Earthquake Engineering,2012,16(5):719-737.
[4] 刘博研,史保平,雷建设.汶川地震对芦山地震及周边断层发震概率的影响[J].地震学报,2013,35(5):642-651.LIU Boyan,SHI Baoping,LEI Jianshe.Effect of Wenchuan earthquake on probabilities of earthquake occurrence of Lushan and surrounding faults [J].Acta Seismologica Sinica,2013,35(5):642-651.(in Chinese)
[5] CAMPBELL K W,BOZORGNIA Y.NGA ground motion for the geometric mean horizontal component of PGA,PGV,PGD and 5% damped linear elastic response spectra for periods ranging from 0.01 to 10s [J].Earthquake Spectra,2008,24(1):139-172.
[6] 边冠博.汶川地震的主余震统计特性及其对结构反应的影响[D].大连:大连理工大学,2012.BIAN Guanbo.The statistical property of mainshock-aftershock sequences of Wenchuan earthquake and its impact on the structures [D].Dalian:Dalian Institute of Technology,2012.(in Chinese)
[7] 卢大伟,李小军,崔建文.汶川中强余震地震动峰值衰减关系 [J].应用基础与工程科学学报,2010,18(S1):138-151.LU Dawei,LI Xiaojun,CUI Jianwen.Ground motion attenuation of the Wenchuan aftershocks [J].Journal of Basic Science and Engineering,2010,18(S1):138-151.(in Chinese)
[8] 刘浪.汶川地震地震动衰减特性分析[D].哈尔滨:中国地震局工程力学研究所,2010.LIU Lang.Analysis about characteristics of ground motion attenuation of Wenchuan earthquake [D].Harbin:Institute of Engineering Mechanics,China Earthquake Administration,2010.(in Chinese)
[9] KANAI K,YOSHIZAWA S,SUZUKI T.An empirical formula for the spectrum of strong earthquake motions II [J].东京大学地震研究所汇报,1963,41:261-270.
[10] ESTEVA L.Seismic risk and seismic design decisions // Seismic Design for Nuclear Power Plants.Cambridge,Mass.:Mass.Inst.Technol.,1970.142-182.
[11] MCGUIRE RK.Seismic ground motion parameter relations [J].Journal of the Geotechnical Engineering Division,1978,104(4):481-490.