汶川地震的面波震级测定及其多普勒效应
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摘要
本文介绍了全球主要地震机构对2008年5月12日汶川地震参数的速报和修订情况,分析了美国地质调查局国家地震信息中心测定的面波震级。通过对比198个全球地震台站测定的面波震级和面波周期,得出如下结论:测定面波震级偏大的台站主要分布在震中的东北方向,测定面波震级偏小的台站主要分布在震中的西南和东南方向,面波周期偏小的台站主要分布在震中东北方向。由于此次地震破裂方向是以北东向单侧破裂为主,且地震多普勒效应导致震中东北方向振动加强,因此该方向上的面波震级偏大,地震烈度衰减慢;而震中西南方向的振动减弱,此方向面波震级偏小,地震烈度衰减快。从而造成地震烈度沿中央断裂带的北东方向衰减慢,而南西方向衰减快的特征分布。
The fast report and revision of the parameters of the Wenchuan earthquake on 12 May 2008 by some major international seismological institutions are introduced, and the surface-wave magnitude measured by National Earthquake Information Center of United States Geological Survey is analyzed in this paper. The comparison of the measured surface-wave magnitudes and periods of 198 global seismic stations reveals that, those stations with larger magnitudes are mainly in NE direction of the epicenter while those with smaller magnitudes are in SW and SE direction, and stations with smaller periods are mainly in NE direction. The seismic intensity map of the Wenchuan earthquake shows that the intensity attenuated slowly in the NE direction of the central fracture zone while the intensity attenuated fast in the SW direction.The reason is that Wenchuan earthquake is a unilateral rupture mainly in NE direction, due to the seismic Doppler effect, the stronger shaking leads to the larger surface-wave magnitudes and slower intensity attenuation in the NE direction of the epicenter, vice versa the weaker shaking leads to the smaller surface-wave magnitudes and faster intensity attenuation in the SW direction.
The fast report and revision of the parameters of the Wenchuan earthquake on 12 May 2008 by some major international seismological institutions are introduced, and the surface-wave magnitude measured by National Earthquake Information Center of United States Geological Survey is analyzed in this paper. The comparison of the measured surface-wave magnitudes and periods of 198 global seismic stations reveals that, those stations with larger magnitudes are mainly in NE direction of the epicenter while those with smaller magnitudes are in SW and SE direction, and stations with smaller periods are mainly in NE direction. The seismic intensity map of the Wenchuan earthquake shows that the intensity attenuated slowly in the NE direction of the central fracture zone while the intensity attenuated fast in the SW direction.The reason is that Wenchuan earthquake is a unilateral rupture mainly in NE direction, due to the seismic Doppler effect, the stronger shaking leads to the larger surface-wave magnitudes and slower intensity attenuation in the NE direction of the epicenter, vice versa the weaker shaking leads to the smaller surface-wave magnitudes and faster intensity attenuation in the SW direction.
引文
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胡聿贤.2006.地震工程学[M].北京:地震出版社:54-56.Hu Y X.2006.Earthquake Engineering[M].Beijing:Seismological Press:54-56(in Chinese).
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张勇,许力生,陈运泰.2009.2008年汶川大地震震源机制的时空变化[J].地球物理学报,52(2):379-389.Zhang Y,Xu L S,Chen Y T.2009.Spatio-temporal variation of the source mechanism of the 2008 great Wenchuan earthquake[J].Chinese Journal of Geophysicis,52(2):379-389(in Chinese).
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Somerville P G,Smith N F,Graves R W,Abrahamson N A.1997.Modification of empirical strong ground motion attenuation relations to include the amplitude and duration effects of rupture direction[J].Seis Res Lett,68(1):199-222.
Swiss Seismological Service.2008.Recent earthquakes Switzerland[DB/OL].[2008-05-12].http://www.seismo.ethz.ch.
SZGRF.2008.Seismological center observatory[DB/OL].[2008-07-01].https://www.szgrf.bgr.de/bulletins.html.
陈运泰,许力生,张勇,杜海林,冯万鹏,刘超,李春来,张红霞.2009.汶川特大地震震源特性分析报告[G]//汶川大地震工程震害调查分析与研究.北京:中国岩石力学与工程学会:6-17.Chen Y T,Xu L S,Zhang Y,Du H L Feng W P,Liu C,Li C L,Zhang H X.2009.Analysis report of the source characters of the great Wenchuan earthquake[G]//Investigation,Analysis and Research on the Engineering Earthquake Damages of the Great Wenchuan Earthquake.Beijing:Chinese Society for Rock Mechanics and Engineering:6-17(in Chinese).
郭履灿,庞明虎.1981.面波震级和它的台基校正值[J].地震学报,3(3):312-320.Guo L C,Pang M H.1981.Surface-wave magnitude and its station correction[J].Acta Seismologica Sinica,3(3):312-320(in Chinese).
胡聿贤.2006.地震工程学[M].北京:地震出版社:54-56.Hu Y X.2006.Earthquake Engineering[M].Beijing:Seismological Press:54-56(in Chinese).
刘瑞丰,陈运泰,任枭,徐志国,王晓欣,邹立晔,张立文.2015.震级的测定[M].北京:地震出版社:1-10.Liu R F,Chen Y T,Ren X,Xu Z G,Wang X X,Zou L Y,Zhang L W.2015.Determination of Magnitude[M].Beijing:Seismological Press:1-10(in Chinese).
刘瑞丰,陈运泰,Peter Bormann,任枭,侯建民,邹立晔.2006.中国地震台网与美国地震台网测定震级的对比Ⅱ:面波震级[J].地震学报,28(1):1-7.Liu R F,Chen Y T,Bormann P,Ren X,Hou J M,Zou L Y.2006.Comparison between earthquake magnitudes determined by China seismograph network and U.S.seismograph network(Ⅱ):Surface wave magnitude[J].Acta Seismologica Sinica,28(1):1-7(in Chinese).
许绍燮.1999.中华人民共和国国家标准《地震震级的规定》(GB 17740-1999)宣贯教材[M].北京:中国标准出版社:1-10.Xu S X.1999.Teaching Book for Propagandizing and Implementing the National Standard of the People’s Republic of China:General Ruler for Earthquake Magnitude(GB 17740-1999)[M].Beijing:Standards Press of China:1-10(in Chinese).
袁一凡.2008.四川汶川8.0级地震灾害损失评估[J].地震工程与工程振动,28(5):10-19.Yuan Y F.2008.The earthquake disaster loss evaluation[J].Earthquake Engineering and Engineering Vibration,28(5):10-19(in Chinese).
张勇,许力生,陈运泰.2009.2008年汶川大地震震源机制的时空变化[J].地球物理学报,52(2):379-389.Zhang Y,Xu L S,Chen Y T.2009.Spatio-temporal variation of the source mechanism of the 2008 great Wenchuan earthquake[J].Chinese Journal of Geophysicis,52(2):379-389(in Chinese).
中国地震台网中心.2008a.地震信息[DB/OL].[2008-05-12].http://www.cenc.ac.cn.China Earthquake Networks Center.2008a.Earthquake information[DB/OL].[2008-05-12].http://www.cenc.ac.cn(in Chinese).
中国地震台网中心.2008b.中国地震台站观测报告[R].北京:中国地震台网中心:1-10.China Earthquake Networks Center.2008b.Seismological Report of the Chinese Seismic Stations[R].Beijing:China Earthquake Networks Center:1-10(in Chinese).
中国地震台网中心.2008c.中国数字地震台网观测报告[R].北京:中国地震台网中心:1-10.China Earthquake Networks Center.2008c.Seismological Report of the Chinese Digital Seismic Network[R].Beijing:China Earthquake Networks Center:1-10(in Chinese).
周庆,张春山,陈献程.2011.汶川MS8.0地震灾害的非对称分布与成因分析[J].地震学报,33(4):492-504.Zhou Q,Zhang C S,Chen X C.2011.Asymmetric disaster distribution and its cause analysis of the MS8.0 Wenchuan earthquake[J].Acta Seismologica Sinica,33(4):492-504(in Chinese).
EMSC.2008.M7.9-Eastern Sichuan,China-2008-05-12 06:28:00 UTC[EB/OL].[2017-10-22].https://www.emsc-csem.org/Earthquake/earthquake.php?id=85969.
GCMT.2008.Monthly CMT solutions[EB/OL].[2017-10-22].http://www.ldeo.columbia.edu/~gcmt/projects/CMT/catalog/NEW_MONTHLY/2008/mar08.ndk.
Gutenberg B.1945.Amplitudes of surface waves and magnitudes of shallow earthquakes[J].Bull Seism Soc Am,35:3-12.
NEIC.2008a.The preliminary determination of epicenters(PDE)bulletin[EB/OL].[2014-10-01].ftp://hazards.cr.usgs.gov/NEICPDE/older PDEdata/mchedr/.
NEIC.2008b.M7.9-eastern Sichuan,China[EB/OL].[2017-10-22].https://earthquake.usgs.gov/earthquakes/eventpage/usp000g650
Somerville P G,Smith N F,Graves R W,Abrahamson N A.1997.Modification of empirical strong ground motion attenuation relations to include the amplitude and duration effects of rupture direction[J].Seis Res Lett,68(1):199-222.
Swiss Seismological Service.2008.Recent earthquakes Switzerland[DB/OL].[2008-05-12].http://www.seismo.ethz.ch.
SZGRF.2008.Seismological center observatory[DB/OL].[2008-07-01].https://www.szgrf.bgr.de/bulletins.html.