基于小波方法分析汶川地震近断层地震动的速度脉冲特性
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摘要
选取断层距小于200km的64组强震记录数据,基于小波方法分析汶川地震近断层速度脉冲的地震动特性,并将此次地震中获取到的速度脉冲周期和幅值参数与Chi-Chi地震和Northridge地震进行了比较,统计分析地震震级、距离对速度脉冲的周期和幅值参数的影响.研究表明:(1)汶川地震近断层速度脉冲具有周期长、幅值小的特点.速度脉冲周期主要分布在6～14s之间,其中51MZQ台沿平行断层的分量脉冲周期最大为14.2s,速度脉冲幅值与Chi-Chi地震和Northridge地震相比明显偏小.(2)速度脉冲记录出现在沿着地震断层破裂传播的方向上,且与地表断裂的距离都在30km以内,这些长周期速度脉冲的形成可能主要由破裂传播的向前方向性效应引起.(3)速度脉冲的周期随矩震级呈对数线性增大,且随断层距增大有减小趋势.在矩震级小于Mw7.5时,观测到的地震动脉冲幅值为50～150cm/s之间,与100cm/s的典型断层滑动速率非常接近;而震级大于Mw7.5时,断层距10km范围内脉冲的幅值已经超过100cm/s,个别记录的脉冲幅值甚至达到200cm/s,远超过前人给出的饱和值,这可能与大的永久形变或该处土层介质条件有关.
Characteristics of near-fault velocity pulses during the Wenchuan earthquake are analyzed based on wavelet analysis methods.64 groups of strong motion records within 200 km to the causative fault are used as database.The amplitude and period characteristics of velocity pulses from Wenchuan earthquake are compared with the Chi-Chi and Northridge earthquake,and the relationships of pulse amplitude and period with magnitude and fault distance are also analyzed.Based on the analysis of near-fault ground motion containing velocity pulses,the following conclusions can be made:(1) The near-fault velocity pulses from Wenchuan earthquake are characterized as long period and low amplitude.The pulse periods are about 6~14 s,with the largest pulse period reaching 14.2 s which is recorded by fault parallel component of the 51MZQ station,and the pulse amplitudes are relatively small for the Wenchuan earthquake compared with the Chi-Chi and Northridge earthquake.(2) Large velocity pulses are observed at sites where the rupture propagated toward the recording station and close to rupture projection with fault distance smaller than 30 km.It can be concluded that the recorded long period pulses are mainly caused by forward directivity effects.(3) The pulse periods are logarithmicly linear increasing with the moment magnitude,and the periods have a trend of decreasing with fault distance.The recorded pulse amplitudes vary from 50~150 cm/s for records with moment magnitude smaller than 7.5,which is very close to the typical slip velocity 100 cm/s;while for records with magnitude larger than 7.5,the pulse amplitudes can easily exceed 100 cm/s,and can reach 200 cm/s for some records,which might be correlated with the larger fling-step and site condition in local area.
Characteristics of near-fault velocity pulses during the Wenchuan earthquake are analyzed based on wavelet analysis methods.64 groups of strong motion records within 200 km to the causative fault are used as database.The amplitude and period characteristics of velocity pulses from Wenchuan earthquake are compared with the Chi-Chi and Northridge earthquake,and the relationships of pulse amplitude and period with magnitude and fault distance are also analyzed.Based on the analysis of near-fault ground motion containing velocity pulses,the following conclusions can be made:(1) The near-fault velocity pulses from Wenchuan earthquake are characterized as long period and low amplitude.The pulse periods are about 6~14 s,with the largest pulse period reaching 14.2 s which is recorded by fault parallel component of the 51MZQ station,and the pulse amplitudes are relatively small for the Wenchuan earthquake compared with the Chi-Chi and Northridge earthquake.(2) Large velocity pulses are observed at sites where the rupture propagated toward the recording station and close to rupture projection with fault distance smaller than 30 km.It can be concluded that the recorded long period pulses are mainly caused by forward directivity effects.(3) The pulse periods are logarithmicly linear increasing with the moment magnitude,and the periods have a trend of decreasing with fault distance.The recorded pulse amplitudes vary from 50~150 cm/s for records with moment magnitude smaller than 7.5,which is very close to the typical slip velocity 100 cm/s;while for records with magnitude larger than 7.5,the pulse amplitudes can easily exceed 100 cm/s,and can reach 200 cm/s for some records,which might be correlated with the larger fling-step and site condition in local area.
引文
[1]Bertero V V,Mahin S A,Hrrera R A.Aseismic designimplications of near-fault San Fernando earthquake records.Earthq.Eng.Struct.Dyn.,1978,6(1):31-42.
[2]MacRac G A,Morrow D V,Roder C W.Near-fault groundmotion effects on simple structures.J.Struct.Eng.,2000,127(9):996-1004.
[3]Malhotra P K.Response of buildings to near field pulse-likeground motions.Earthq.Eng.Struct.Dyn.,1999,28(11):1309-1326.
[4]Iwan W D,Chen X.Important near-field ground motion datafrom the Landers earthquake.//Proceeding 10th EuropeanConference on Earthquake Engineering.Vienna,Austria.,1994:229-234.
[5]Iwan W D.Drift spectrum:measure of demand forearthquake ground motions.J.Struct.Eng.,1997,123(4):397-404.
[6]Somerville P.Characterization of ground motion at the sitesof subjected buildings.SAC Joint Venture Rep,1995,SAC95-03.
[7]Somerville P G,Smith N F,Graves R W,et al.Modificationof empirical strong ground motion attenuation relations toinclude the amplitude and duration effects of rupturedirectivity.Seism.Res.Lett.,1997,68(1):199-222.
[8]Huang B S,Chen K C,Wang W G,et al.Characteristics ofstrong ground motion across a thrust fault tip from theSeptember 21,1999,Chi-Chi,Taiwan earthquake.Geophys.Res.Lett.,2000,27(17):2729-2732.
[9]Chen K C,Huang B S,Wang J H,et al.An observation ofrupture pulses of the 20September 1999Chi-Chi,Taiwan,earthquake from near-field seismograms.Bull.Seism.Soc.Am.,2001,91(5):1247-1254.
[10]Alavi B,Krawinkler H.Consideration of near-fault groundmotion effects in seismic design.//Proceedings 6th WorldConference on Earthquake Engineering.New Zealand:TheNew Zealand Society for Earthquake Engineering.2000,2665:1-8.
[11]Somerville P G.Magnitude scaling of the near faultdirectivity pulse.Phy.Earth Planet.Int.,2003,137(1-4):201-212.
[12]Mavroeidis G P,Papageorgiou A S.A mathematicalrepresentation of near-fault ground motions.Bull.Seism.Soc.Am.,2003,93(3):1099-1131.
[13]Bray J D,Rodriguez-Marek A.Characterization of forwarddirectivity ground motions in the near-fault region.Soil Dyn.&Earthq.Eng.,2004,24(11):8l5-828.
[14]韦韬,赵凤新,张郁山.近断层速度脉冲的地震动特性研究.地震学报,2006,28(6):629-637.Wei T,Zhao F X,Zhang Y S.Characteristics of near-faultground motion containing velocity pulses.Acta SeismologicaSinica(in Chinese),2006,28(6):629-637.
[15]Baker J W.Quantitative classification of near-fault groundmotions using wavelet analysis.Bull.Seism.Soc.Am.,2007,97(5):1486-1501.
[16]Li X J,Zhou Z H,Huang M,et al.Preliminary analysis ofstrong-motion recordings from the magnitude 8.0Wenchuan,China,earthquake of May 12.Seism.Res.Lett.,2008,79(6):844-854.
[17]Li X J,Liu L,Wang Y S,et al.Analysis of horizontalstrong-motion attenuation in the great 2008 Wenchuanearthquake.Bull.Seism.Soc.Am.,2010,100(5B):2440-2449.
[18]于海英,王栋,杨永强等.汶川8.0级地震强震动特征初步分析.震灾防御技术,2008,3(4):321-336.Yu H Y,Wang D,Yang Y Q,et al.The preliminaryanalysis of strong ground motion characteristics from theMs8.0 Wenchuan earthquake,China.Technology forEarthquake Disaster Prevention(in Chinese),2008,3(4):321-336.
[19]Lu M,Li X J,An X W,et al.A preliminary study on thenear-source strong-motion characteristics of the great 2008Wenchuan earthquake in China.Bull.Seism.Soc.Am.,2010,100(5B):2491-2507.
[20]Wen Z P,Xie J J,Gao M T,et al.Near-source groundmotion characteristics of the Ms8.0 Wenchuan earthquake.Bull.Seism.Soc.Am.,2010,100(5B):2425-2439.
[21]谢俊举,温增平,高孟潭等.2008年汶川地震近断层地震动的非平稳特征.地球物理学报,2011,54(3):728-736.Xie J J,Wen Z P,Gao M T,et al.Non-stationarycharacteristics of near-fault strong motions during the 2008Wenchuan earthquake.Chinese J.Geophys.(in Chinese),2011,54(3):728-736.
[22]朱继梅.小波变换及其工程应用.振动与冲击,1996,15(4):94-100.Zhu J M.Wavelet transform and its engineering applications.Journal of Vibration and Shock(in Chinese),1996,15(4):94-100.
[23]石春香,罗奇峰.时程信号的Hilbert-Huang变换与小波分析.地震学报,2003,25(4):398-405.Shi C X,Luo Q F.Hilbert-Huang transform and waveletanalysis of time history signal.Acta Seismologica Sinica(inChinese),2003,25(4):398-405.
[24]赵凤新,韦韬,张郁山.近断层速度脉冲对钢筋混凝土框架结构地震反应的影响.工程力学,2008,25(10):180-187.Zhao F X,Wei T,Zhang Y S.Influence of near-fault velocitypulse on the seismic response of reinforced concrete frame.Engineering Mechanics(in Chinese),2008,25(10):180-187.
[25]杨迪雄,李刚,程耿东.近断层脉冲型地震动作用下隔震结构地震反应分析.地震工程与工程振动,2005,25(2):119-124.Yang D X,Li G,Cheng G D.Seismic analysis of base-isolated structures subjected to near-fault pulse-like groundmotions.Earthquake Engineering&Engineering Vibration(in Chinese),2005,25(2):119-124.
[26]杨迪雄,潘建伟,李刚.近断层脉冲型地震动作用下建筑结构的层间变形分布特征和机理分析.建筑结构学报,2009,30(4):108-118.Yang D X,Pan J W,Li G.Deformational distributionfeature and mechanism analysis of building structuressubjected to near-fault pulse-type ground motions.Journalof Building Structures(in Chinese),2009,30(4):108-118.
[27]Anderson J C,Bertero V V.Uncertainties in establishingdesign earthquakes.J.Struct.Eng.,ASCE,1987,113(8):1709-1724.
[28]Hall J F,Heaton T H,Halling M W,et al.Near-sourceground motion and its effects on flexible buildings.Earthquake Spectra,1995,11(4):569-604.
[29]Makris N.Rigidity-plasticity-viscosity:can electrorheologicaldampers protect base-isolated structures from near-sourceground motions?Earthq.Eng.Struct.Dyn.,1997,26(5):571-591.
[30]王卫民,赵连锋,李娟等.四川汶川8.0级地震震源过程.地球物理学报,2008,51(5):1403-1410.Wang W M,Zhao L F,Li J,et al.Rupture process of theMs8.0Wenchuan earthquake of Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(5):1403-1410.
[31]张勇,冯万鹏,许力生等.2008年汶川大地震的时空破裂过程.中国科学-D辑:地球科学,2008,38(10):1186-1194.Zhang Y,Feng W P,Xu L S,et al.Spatial-temporal ruptureprocess of the 2008great Wenchuan earthquake.Science inChina Series D-Earth Sciences(in Chinese),2008,38(10):1186-1194.
[32]徐锡伟,闻学泽,叶建青等.汶川Ms8.0地震地表破裂带及其发震构造.地震地质,2008,30(3):597-627.Xu X W,Wen X Z,Ye J Q,et al.Discovery of theWenchuan Ms8.0earthquake surface ruptures and discussionfor its seismogenic structures.Seismology and Geology(inChinese),2008,30(3):597-627.
[33]Brune J N.Tectonic stress and the spectra of seismic shearwaves from earthquakes.J.Geophys.Res.,1970,75(26):4997-5009.
[34]Aki K.Strong-motion seismology,in earthquakes:observation,theory and interpretation.∥Kanamori H,Boschi E,eds.Proceeding of the International School of Physics,‘EnricoFermi’.Amsterdam:North-Holland,1983,85:223-250.
[35]赵翠萍,陈章立,周连庆等.汶川Mw8.0级地震震源破裂过程研究:分段特征.科学通报,2009,54(22):3475-3482.Zhao C P,Chen Z L,Zhou L Q,et al.Rupture process ofthe 8.0 Wenchuan earthquake of Sichuan,China:thesegmentation feature.Chinese Sci.Bull.(in Chinese),2009,54(22):3475-3482.
[36]杜海林,许力生,陈运泰.利用阿拉斯加台阵资料分析2008年汶川大地震的破裂过程.地球物理学报,2009,52(2):372-378.Du H L,Xu L S,Chen Y T.Rupture process of the 2008great Wenchuan earthquake from the analysis of the Alaskaarray data.Chinese J.Geophys.(in Chinese),2009,52(2):372-378.
[2]MacRac G A,Morrow D V,Roder C W.Near-fault groundmotion effects on simple structures.J.Struct.Eng.,2000,127(9):996-1004.
[3]Malhotra P K.Response of buildings to near field pulse-likeground motions.Earthq.Eng.Struct.Dyn.,1999,28(11):1309-1326.
[4]Iwan W D,Chen X.Important near-field ground motion datafrom the Landers earthquake.//Proceeding 10th EuropeanConference on Earthquake Engineering.Vienna,Austria.,1994:229-234.
[5]Iwan W D.Drift spectrum:measure of demand forearthquake ground motions.J.Struct.Eng.,1997,123(4):397-404.
[6]Somerville P.Characterization of ground motion at the sitesof subjected buildings.SAC Joint Venture Rep,1995,SAC95-03.
[7]Somerville P G,Smith N F,Graves R W,et al.Modificationof empirical strong ground motion attenuation relations toinclude the amplitude and duration effects of rupturedirectivity.Seism.Res.Lett.,1997,68(1):199-222.
[8]Huang B S,Chen K C,Wang W G,et al.Characteristics ofstrong ground motion across a thrust fault tip from theSeptember 21,1999,Chi-Chi,Taiwan earthquake.Geophys.Res.Lett.,2000,27(17):2729-2732.
[9]Chen K C,Huang B S,Wang J H,et al.An observation ofrupture pulses of the 20September 1999Chi-Chi,Taiwan,earthquake from near-field seismograms.Bull.Seism.Soc.Am.,2001,91(5):1247-1254.
[10]Alavi B,Krawinkler H.Consideration of near-fault groundmotion effects in seismic design.//Proceedings 6th WorldConference on Earthquake Engineering.New Zealand:TheNew Zealand Society for Earthquake Engineering.2000,2665:1-8.
[11]Somerville P G.Magnitude scaling of the near faultdirectivity pulse.Phy.Earth Planet.Int.,2003,137(1-4):201-212.
[12]Mavroeidis G P,Papageorgiou A S.A mathematicalrepresentation of near-fault ground motions.Bull.Seism.Soc.Am.,2003,93(3):1099-1131.
[13]Bray J D,Rodriguez-Marek A.Characterization of forwarddirectivity ground motions in the near-fault region.Soil Dyn.&Earthq.Eng.,2004,24(11):8l5-828.
[14]韦韬,赵凤新,张郁山.近断层速度脉冲的地震动特性研究.地震学报,2006,28(6):629-637.Wei T,Zhao F X,Zhang Y S.Characteristics of near-faultground motion containing velocity pulses.Acta SeismologicaSinica(in Chinese),2006,28(6):629-637.
[15]Baker J W.Quantitative classification of near-fault groundmotions using wavelet analysis.Bull.Seism.Soc.Am.,2007,97(5):1486-1501.
[16]Li X J,Zhou Z H,Huang M,et al.Preliminary analysis ofstrong-motion recordings from the magnitude 8.0Wenchuan,China,earthquake of May 12.Seism.Res.Lett.,2008,79(6):844-854.
[17]Li X J,Liu L,Wang Y S,et al.Analysis of horizontalstrong-motion attenuation in the great 2008 Wenchuanearthquake.Bull.Seism.Soc.Am.,2010,100(5B):2440-2449.
[18]于海英,王栋,杨永强等.汶川8.0级地震强震动特征初步分析.震灾防御技术,2008,3(4):321-336.Yu H Y,Wang D,Yang Y Q,et al.The preliminaryanalysis of strong ground motion characteristics from theMs8.0 Wenchuan earthquake,China.Technology forEarthquake Disaster Prevention(in Chinese),2008,3(4):321-336.
[19]Lu M,Li X J,An X W,et al.A preliminary study on thenear-source strong-motion characteristics of the great 2008Wenchuan earthquake in China.Bull.Seism.Soc.Am.,2010,100(5B):2491-2507.
[20]Wen Z P,Xie J J,Gao M T,et al.Near-source groundmotion characteristics of the Ms8.0 Wenchuan earthquake.Bull.Seism.Soc.Am.,2010,100(5B):2425-2439.
[21]谢俊举,温增平,高孟潭等.2008年汶川地震近断层地震动的非平稳特征.地球物理学报,2011,54(3):728-736.Xie J J,Wen Z P,Gao M T,et al.Non-stationarycharacteristics of near-fault strong motions during the 2008Wenchuan earthquake.Chinese J.Geophys.(in Chinese),2011,54(3):728-736.
[22]朱继梅.小波变换及其工程应用.振动与冲击,1996,15(4):94-100.Zhu J M.Wavelet transform and its engineering applications.Journal of Vibration and Shock(in Chinese),1996,15(4):94-100.
[23]石春香,罗奇峰.时程信号的Hilbert-Huang变换与小波分析.地震学报,2003,25(4):398-405.Shi C X,Luo Q F.Hilbert-Huang transform and waveletanalysis of time history signal.Acta Seismologica Sinica(inChinese),2003,25(4):398-405.
[24]赵凤新,韦韬,张郁山.近断层速度脉冲对钢筋混凝土框架结构地震反应的影响.工程力学,2008,25(10):180-187.Zhao F X,Wei T,Zhang Y S.Influence of near-fault velocitypulse on the seismic response of reinforced concrete frame.Engineering Mechanics(in Chinese),2008,25(10):180-187.
[25]杨迪雄,李刚,程耿东.近断层脉冲型地震动作用下隔震结构地震反应分析.地震工程与工程振动,2005,25(2):119-124.Yang D X,Li G,Cheng G D.Seismic analysis of base-isolated structures subjected to near-fault pulse-like groundmotions.Earthquake Engineering&Engineering Vibration(in Chinese),2005,25(2):119-124.
[26]杨迪雄,潘建伟,李刚.近断层脉冲型地震动作用下建筑结构的层间变形分布特征和机理分析.建筑结构学报,2009,30(4):108-118.Yang D X,Pan J W,Li G.Deformational distributionfeature and mechanism analysis of building structuressubjected to near-fault pulse-type ground motions.Journalof Building Structures(in Chinese),2009,30(4):108-118.
[27]Anderson J C,Bertero V V.Uncertainties in establishingdesign earthquakes.J.Struct.Eng.,ASCE,1987,113(8):1709-1724.
[28]Hall J F,Heaton T H,Halling M W,et al.Near-sourceground motion and its effects on flexible buildings.Earthquake Spectra,1995,11(4):569-604.
[29]Makris N.Rigidity-plasticity-viscosity:can electrorheologicaldampers protect base-isolated structures from near-sourceground motions?Earthq.Eng.Struct.Dyn.,1997,26(5):571-591.
[30]王卫民,赵连锋,李娟等.四川汶川8.0级地震震源过程.地球物理学报,2008,51(5):1403-1410.Wang W M,Zhao L F,Li J,et al.Rupture process of theMs8.0Wenchuan earthquake of Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(5):1403-1410.
[31]张勇,冯万鹏,许力生等.2008年汶川大地震的时空破裂过程.中国科学-D辑:地球科学,2008,38(10):1186-1194.Zhang Y,Feng W P,Xu L S,et al.Spatial-temporal ruptureprocess of the 2008great Wenchuan earthquake.Science inChina Series D-Earth Sciences(in Chinese),2008,38(10):1186-1194.
[32]徐锡伟,闻学泽,叶建青等.汶川Ms8.0地震地表破裂带及其发震构造.地震地质,2008,30(3):597-627.Xu X W,Wen X Z,Ye J Q,et al.Discovery of theWenchuan Ms8.0earthquake surface ruptures and discussionfor its seismogenic structures.Seismology and Geology(inChinese),2008,30(3):597-627.
[33]Brune J N.Tectonic stress and the spectra of seismic shearwaves from earthquakes.J.Geophys.Res.,1970,75(26):4997-5009.
[34]Aki K.Strong-motion seismology,in earthquakes:observation,theory and interpretation.∥Kanamori H,Boschi E,eds.Proceeding of the International School of Physics,‘EnricoFermi’.Amsterdam:North-Holland,1983,85:223-250.
[35]赵翠萍,陈章立,周连庆等.汶川Mw8.0级地震震源破裂过程研究:分段特征.科学通报,2009,54(22):3475-3482.Zhao C P,Chen Z L,Zhou L Q,et al.Rupture process ofthe 8.0 Wenchuan earthquake of Sichuan,China:thesegmentation feature.Chinese Sci.Bull.(in Chinese),2009,54(22):3475-3482.
[36]杜海林,许力生,陈运泰.利用阿拉斯加台阵资料分析2008年汶川大地震的破裂过程.地球物理学报,2009,52(2):372-378.Du H L,Xu L S,Chen Y T.Rupture process of the 2008great Wenchuan earthquake from the analysis of the Alaskaarray data.Chinese J.Geophys.(in Chinese),2009,52(2):372-378.
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