利用背景噪声互相关研究汶川地震震源区地震波速度变化
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摘要
利用2007年3月至2009年3月四川数字地震台网的宽频带连续波形资料,通过计算地震背景噪声互相关提取台站对间的经验格林函数,在0.1～0.5 Hz频带下测量每天经验格林函数与参考经验格林函数的走时偏移,进而得到各台站对在该时段内的相对地震波速度变化.结果表明,2008年5月12日汶川M_s8.0级地震造成了震源区地震波速度的急剧降低,最大降幅达0.4%;大致以安县为界,余震带西南部地区在汶川主震后波速降即达到最大值,而东北部地区的最大波速降一般出现在主震后的1～4个月,相对地震波速度变化的这种分段特性与地震序列的时空分布特征有较好的对应关系;在震源区外围的四川盆地也观测到了震后波速降低,而川西高原内部则没有出现显著的波速变化.进一步的分析和计算结果表明主震的静态应力变化和强地面运动引起的地表破坏都不能很好地解释震后波速的急剧降低,地震导致的断层区内部结构破坏和周边介质应力状态改变可能是波速变化的主要原因.
We detected the variations of crustal seismic velocity around the M_s8.0 Wenchuan earthquake fault zone during March 2007-March 2009 from ambient noise cross-correlation by using continuous seismic data recorded by the broadband stations of Sichuan digital seismic network.The data processing procedure was divided into three phases: (1) single station data preparation including time domain normalization, spectral whitening, (2) cross-correlation and temporal stacking of 31-day daily cross-correlation functions (CCF), and (3) estimation of relative velocity change by measuring travel time shifts in frequency 0.1～0.5 Hz between the 31- day stacks and the reference empirical Green function, which was the stack of 14 months of CCF before the Wenchuan earthquake.The preliminary results revealed a sudden post-seismic velocity drop for the station pairs across the Longmenshan fault, the largest of which was more than 0.4%.The seismic velocity changes with time exhibited a spatial difference: in the southwest segment of the Longmenshan fault, the maximum value of velocity reduction occurred at the time immediately after the Wenchuan earthquake, whereas in the northeast segment of the fault velocity reduction appeared 1～4 months after the main earthquake.Furthermore, the spatial extent and magnitude of the post-seismic velocity change in the Sichuan Basin exceeded that in the mountainous regions west of the fault zone.The static stress change and near-surface physical damage caused by strong ground motion could not entirely explain the measurements in this study.We think the temporal changes of seismic velocity maybe related to the damages from fault ruptures and stress changes around the fault zones.
We detected the variations of crustal seismic velocity around the M_s8.0 Wenchuan earthquake fault zone during March 2007-March 2009 from ambient noise cross-correlation by using continuous seismic data recorded by the broadband stations of Sichuan digital seismic network.The data processing procedure was divided into three phases: (1) single station data preparation including time domain normalization, spectral whitening, (2) cross-correlation and temporal stacking of 31-day daily cross-correlation functions (CCF), and (3) estimation of relative velocity change by measuring travel time shifts in frequency 0.1～0.5 Hz between the 31- day stacks and the reference empirical Green function, which was the stack of 14 months of CCF before the Wenchuan earthquake.The preliminary results revealed a sudden post-seismic velocity drop for the station pairs across the Longmenshan fault, the largest of which was more than 0.4%.The seismic velocity changes with time exhibited a spatial difference: in the southwest segment of the Longmenshan fault, the maximum value of velocity reduction occurred at the time immediately after the Wenchuan earthquake, whereas in the northeast segment of the fault velocity reduction appeared 1～4 months after the main earthquake.Furthermore, the spatial extent and magnitude of the post-seismic velocity change in the Sichuan Basin exceeded that in the mountainous regions west of the fault zone.The static stress change and near-surface physical damage caused by strong ground motion could not entirely explain the measurements in this study.We think the temporal changes of seismic velocity maybe related to the damages from fault ruptures and stress changes around the fault zones.
引文
[1] 张培震,徐锡伟,闻学泽等.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因.地球物理学报,2008,51(4) :1066～1073 Zhang P Z,Xu X W,Wen X Z,et al.Slip rates and recurrence intervals of the Longmen Shan active fault zone,and tectonic implications for the mechanism of the May 12 Wenchuan earthquake,2008,Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(4) :1066～1073
[2] Royden L H,Burchiel B C,Van der Hilst R D,et al.The geological evolution of the Tibetan Plateau.Science,2008,321:1054～1058
[3] 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 the M_s 8.0 Wenehuan earthquake of Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(5) :1403～1410
[4] 张勇,许力生,陈运泰.2008年汶川大地震震源机制的时空变化.地球物理学报,2009,52(2) :379～389 Zhang Y,Xu L S,Chen Y T.Spatio-temperal variation of the source mechanism of the 2008 great Wenchuan earthquake.Chinese J.Geophys.(in Chinese),2009,52(2) :379～389
[5] 吴建平,黄媛,张天中等.汶川M_s 8.0级地震余震分布及周边区域P波三维速度结构研究.地球物理学报,2009,52(2) : 320～328 Wu J P,H uang Y,Zhang T Z,et al.Aftershock distribution of the Ms8.0 Wenchuan earthquake and three dimension P-wave velocity structure in and around source region.Chinese J.Geophys.(in Chinese),2009,52(2) :320～328
[6] Wang Z,Fukao Y,Pei S P.Structural control of rupturing of the M_w7.9 2008 Wenchuan Earthquake,China.Earth Planet.Sci.Lett.,2009,279:131～138
[7] “中国地壳运动观测网络”项目组.GPS测定的2008年汶川M_s 8.0级地震的同震位移场.中国科学(D辑),2008,38(10) :1195～1206 The Project of Crustal Movement Observation Network of China.The coseismic displacement fields of Wenchuan M,8.0 earthquake occurrence in 2008 using GPS data.Science in China(Series D)(in Chinese),2008,38(10) :1195～1206
[8] 江在森,方颖,武艳强等.汶川8.0级地震前区域地壳运动与变形动态过程.地球物理学报,2009,52(2) :505～518 Jiang Z X,Fang Y,Wu Y Q,et al.The dynamic process of regional crustal movement and deformation before Wenchuan M_s8.0 earthquake.Chinese J.Geophys.(in Chinese),2009,52(2) :505～518
[9] Mooney W D,Ginzburg A.Seismic measurements of the internal properties of fault zones.Pure Appl.Geophys.,1986,124:141～157
[10] Scholz C H.The Mechanics of Earthquakes and Faulting.New York:Cambridge University Press,2002
[11] Kanamori H.Mechanics of earthquakes.Ann.Rev.Earth Planet Sci.,1994,22:207～237
[12] Semenov A N.Variation in the travel time of transverse and longitudinal waves before violent earthquakes.Bull.Acad.Sci.USSR,Phys.Solid Earth,1969,3:245～248
[13] Crampin S,Booth D C,Evans R,et al.Changes in shear wave splitting at Anza near the time of the North Palm Springs earthquake.J.Geophys.Res.,1990,95(B7) :11197～11212
[14] Jin A,Aki K.Temporal change in coda Q before the Tangshan earthquake of 1976 and the Haicheng earthquake of 1975.J.Geophys.Res.,1986,91(B1) :665～673
[15] Reasenberg P,Aki K.A precise,continuous measurement of seismic velocity for monitoring in situ stress.J.Geophys.Res.,1974,79(2) :399～406
[16] Poupinet G,Ellsworth W L,Frechet J.Monitoring velocity variations in the crust using earthquake doublets: An application to the Calaveras Fault,California.J.Geophys.Res.,1984,89(B7) : 5719～5731
[17] 丁志峰,武岩,王辉等.2008年汶川地震震源区横波分裂的变化特征.中国科学(D辑),2008,38(12) :1600～1604 Ding Z F,Wu Y,Wang H,et al.Variations of shear wave splitting in the 2008 Wenchuan earthquake region.Science in China(Series D)(in Chinese),2008,38(12) :1600～1604
[18] Sens-Schnfelder C,Wegler U.Passive image interferometry and seasonal variations of seismic velocities at Merapi volcano,Indonesia.Geophys.Res.Lett.,2006,33(L21302)
[19] Brenguier F,Shapiro N M,Campillo M,et al.Towards forecasting volcanic eruptions using seismic noise.Nature Geoscience,2008,1:126～130
[20] Wegler U,Sens-Schnfelder C.Fault zone monitoring with Passive Image Interferometry.Geophys.J.Int.,2007,168:1029～1033
[21] Wegler U,Nakahara H,Sens-Schnfelder C,et al.Sudden drop of seismic velocity after the 2004 M_w 6.6 mid-Niigata earthquake,Japan,observed with Passive Image Interferometry.J.Geophys.Res.,2009,114(B06305)
[22] Brenguier F,Campillo M,Hadziioannou C,et al.Postseismic relaxation along the San Andreas fault at Parkfield from continuous seismological observations.Science,2009,321: 1478～1481
[23] Xu Z J,Song X D.Temporal changes of surface wave velocity associated with major Sumatra earthquakes from ambient noise correlation.PNAS,2009,106(34) :14207～14212
[24] 吕坚,苏金蓉,靳玉科等.汶川8.0级地震序列重新定位及其发震构造初探.地震地质,2008,30(4) :917～925 Lü J,Su J R,Jin Y K,et al.Discussion on relocation and seismo-tectonics of the M_s 8.0 Wenchuan earthquake sequences.Seismology and Geology(in Chinese),2008,30(4) :917～925
[25] 徐锡伟,闻学泽,叶建青等.汶川M_s 8.0地震地表破裂带及其 发震构造.地震地质,2008,30(3) :597～629 Xu X W,Wen X Z,Ye J Q,et al.The M_s 8.0 Wenchuan earthquake surface ruptures and its seismogenic structure.Seismology and Geology(in Chinese),2008,30(3) :597～629
[26] Bensen G D,Ritzwoller M H,barmin M P,et al.Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements.Geophys.J.Int.,2007,169:1239～1260
[27] Shapiro N M,Campillo M,Stehly L,et al.High resolution surface wave tomography from ambient seismic noise.Science,2005,307:1615～1618
[28] Stehly L,Campillo M,Shapiro N M.A study of the seismic noise from its long-range correlation properties.J.Geophys.Res.,2006,111(B10306)
[29] Stehly L,Campillo M,Shapiro N M.Traveltime measurements from noise correlations:stability and detection of instrumental time-shifts.Geophys.J.Int.,2007,171: 223～230
[30] Li Y G,Vidale J E,Aki K,et al.Evidence of shallow fault zone strengthening after the 1992 M7.5 Landers,California,earthquake.Science,1998,279:217～219
[31] Vidale J E,Li Y G.Damage to the shallow Landers fault from the nearby Hector Mine earthquake.Nature,2003,421:524～526
[32] Rubinstein J L,Beroza G C.Evidence for widespread nonlinear strong ground motion in the M_w 6.9 Loma Prieta earthquake.Bull.Seismol.Soc.Am.,2004,94(5) :1595～1608
[33] Rubinstein J L,Beroza G C.Depth constraints on nonlinear strong ground motion from the 2004 Parkfield earthquake.Geophys.Res.Lett.,2005,32(L14313)
[34] Peng Z G,Ben-Zion Y.Temporal changes of shallow seismic velocity around the karadere-düzce branch of the north anatolian fault and strong ground motion.Pure Appl.Geophys.,2006,163:567～600
[35] Niu F L,Silver P G,Daley T M,et al.Preseismic velocity changes observed from active source monitoring at the Parkfield SAFOD drill site.Nature,2008,454:204～208
[36] Snieder R,Gret A,Douma H,et al.Coda Wave Interferometry for estimating nonlinear behaviour in seismic velocity.Science,2002,295:2253～2255
[37] Li X J,Zhou Z H,Huang M,et al.Preliminary analysis of strong-motion recordings from the magnitude 8.0 Wenchuan,China,Earthquake of 12 May 2008.Seismol.Res.Lett.,2008,79(6) :844～854
[38] Lin J,Stein R S.Stress triggering in thrust and subduction earthquakes,and stress interaction between the southern San Andreas and nearby thrust and strike-slip faults.J.Geophys.Res.,2004,109(B02303)
[39] Okada Y.Internal deformation due to shear and tensile faults in a half-space.Bull.Seismol.Soc.Am.,1992,82:1018～1040
[40] Zhou Y,Nolet G F,Dahlen A,et al.Global upper-mantle structure from finite-frequency surface-wave tomography.J.Geophys.Res.,2006,111(B04304)
[2] Royden L H,Burchiel B C,Van der Hilst R D,et al.The geological evolution of the Tibetan Plateau.Science,2008,321:1054～1058
[3] 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 the M_s 8.0 Wenehuan earthquake of Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(5) :1403～1410
[4] 张勇,许力生,陈运泰.2008年汶川大地震震源机制的时空变化.地球物理学报,2009,52(2) :379～389 Zhang Y,Xu L S,Chen Y T.Spatio-temperal variation of the source mechanism of the 2008 great Wenchuan earthquake.Chinese J.Geophys.(in Chinese),2009,52(2) :379～389
[5] 吴建平,黄媛,张天中等.汶川M_s 8.0级地震余震分布及周边区域P波三维速度结构研究.地球物理学报,2009,52(2) : 320～328 Wu J P,H uang Y,Zhang T Z,et al.Aftershock distribution of the Ms8.0 Wenchuan earthquake and three dimension P-wave velocity structure in and around source region.Chinese J.Geophys.(in Chinese),2009,52(2) :320～328
[6] Wang Z,Fukao Y,Pei S P.Structural control of rupturing of the M_w7.9 2008 Wenchuan Earthquake,China.Earth Planet.Sci.Lett.,2009,279:131～138
[7] “中国地壳运动观测网络”项目组.GPS测定的2008年汶川M_s 8.0级地震的同震位移场.中国科学(D辑),2008,38(10) :1195～1206 The Project of Crustal Movement Observation Network of China.The coseismic displacement fields of Wenchuan M,8.0 earthquake occurrence in 2008 using GPS data.Science in China(Series D)(in Chinese),2008,38(10) :1195～1206
[8] 江在森,方颖,武艳强等.汶川8.0级地震前区域地壳运动与变形动态过程.地球物理学报,2009,52(2) :505～518 Jiang Z X,Fang Y,Wu Y Q,et al.The dynamic process of regional crustal movement and deformation before Wenchuan M_s8.0 earthquake.Chinese J.Geophys.(in Chinese),2009,52(2) :505～518
[9] Mooney W D,Ginzburg A.Seismic measurements of the internal properties of fault zones.Pure Appl.Geophys.,1986,124:141～157
[10] Scholz C H.The Mechanics of Earthquakes and Faulting.New York:Cambridge University Press,2002
[11] Kanamori H.Mechanics of earthquakes.Ann.Rev.Earth Planet Sci.,1994,22:207～237
[12] Semenov A N.Variation in the travel time of transverse and longitudinal waves before violent earthquakes.Bull.Acad.Sci.USSR,Phys.Solid Earth,1969,3:245～248
[13] Crampin S,Booth D C,Evans R,et al.Changes in shear wave splitting at Anza near the time of the North Palm Springs earthquake.J.Geophys.Res.,1990,95(B7) :11197～11212
[14] Jin A,Aki K.Temporal change in coda Q before the Tangshan earthquake of 1976 and the Haicheng earthquake of 1975.J.Geophys.Res.,1986,91(B1) :665～673
[15] Reasenberg P,Aki K.A precise,continuous measurement of seismic velocity for monitoring in situ stress.J.Geophys.Res.,1974,79(2) :399～406
[16] Poupinet G,Ellsworth W L,Frechet J.Monitoring velocity variations in the crust using earthquake doublets: An application to the Calaveras Fault,California.J.Geophys.Res.,1984,89(B7) : 5719～5731
[17] 丁志峰,武岩,王辉等.2008年汶川地震震源区横波分裂的变化特征.中国科学(D辑),2008,38(12) :1600～1604 Ding Z F,Wu Y,Wang H,et al.Variations of shear wave splitting in the 2008 Wenchuan earthquake region.Science in China(Series D)(in Chinese),2008,38(12) :1600～1604
[18] Sens-Schnfelder C,Wegler U.Passive image interferometry and seasonal variations of seismic velocities at Merapi volcano,Indonesia.Geophys.Res.Lett.,2006,33(L21302)
[19] Brenguier F,Shapiro N M,Campillo M,et al.Towards forecasting volcanic eruptions using seismic noise.Nature Geoscience,2008,1:126～130
[20] Wegler U,Sens-Schnfelder C.Fault zone monitoring with Passive Image Interferometry.Geophys.J.Int.,2007,168:1029～1033
[21] Wegler U,Nakahara H,Sens-Schnfelder C,et al.Sudden drop of seismic velocity after the 2004 M_w 6.6 mid-Niigata earthquake,Japan,observed with Passive Image Interferometry.J.Geophys.Res.,2009,114(B06305)
[22] Brenguier F,Campillo M,Hadziioannou C,et al.Postseismic relaxation along the San Andreas fault at Parkfield from continuous seismological observations.Science,2009,321: 1478～1481
[23] Xu Z J,Song X D.Temporal changes of surface wave velocity associated with major Sumatra earthquakes from ambient noise correlation.PNAS,2009,106(34) :14207～14212
[24] 吕坚,苏金蓉,靳玉科等.汶川8.0级地震序列重新定位及其发震构造初探.地震地质,2008,30(4) :917～925 Lü J,Su J R,Jin Y K,et al.Discussion on relocation and seismo-tectonics of the M_s 8.0 Wenchuan earthquake sequences.Seismology and Geology(in Chinese),2008,30(4) :917～925
[25] 徐锡伟,闻学泽,叶建青等.汶川M_s 8.0地震地表破裂带及其 发震构造.地震地质,2008,30(3) :597～629 Xu X W,Wen X Z,Ye J Q,et al.The M_s 8.0 Wenchuan earthquake surface ruptures and its seismogenic structure.Seismology and Geology(in Chinese),2008,30(3) :597～629
[26] Bensen G D,Ritzwoller M H,barmin M P,et al.Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements.Geophys.J.Int.,2007,169:1239～1260
[27] Shapiro N M,Campillo M,Stehly L,et al.High resolution surface wave tomography from ambient seismic noise.Science,2005,307:1615～1618
[28] Stehly L,Campillo M,Shapiro N M.A study of the seismic noise from its long-range correlation properties.J.Geophys.Res.,2006,111(B10306)
[29] Stehly L,Campillo M,Shapiro N M.Traveltime measurements from noise correlations:stability and detection of instrumental time-shifts.Geophys.J.Int.,2007,171: 223～230
[30] Li Y G,Vidale J E,Aki K,et al.Evidence of shallow fault zone strengthening after the 1992 M7.5 Landers,California,earthquake.Science,1998,279:217～219
[31] Vidale J E,Li Y G.Damage to the shallow Landers fault from the nearby Hector Mine earthquake.Nature,2003,421:524～526
[32] Rubinstein J L,Beroza G C.Evidence for widespread nonlinear strong ground motion in the M_w 6.9 Loma Prieta earthquake.Bull.Seismol.Soc.Am.,2004,94(5) :1595～1608
[33] Rubinstein J L,Beroza G C.Depth constraints on nonlinear strong ground motion from the 2004 Parkfield earthquake.Geophys.Res.Lett.,2005,32(L14313)
[34] Peng Z G,Ben-Zion Y.Temporal changes of shallow seismic velocity around the karadere-düzce branch of the north anatolian fault and strong ground motion.Pure Appl.Geophys.,2006,163:567～600
[35] Niu F L,Silver P G,Daley T M,et al.Preseismic velocity changes observed from active source monitoring at the Parkfield SAFOD drill site.Nature,2008,454:204～208
[36] Snieder R,Gret A,Douma H,et al.Coda Wave Interferometry for estimating nonlinear behaviour in seismic velocity.Science,2002,295:2253～2255
[37] Li X J,Zhou Z H,Huang M,et al.Preliminary analysis of strong-motion recordings from the magnitude 8.0 Wenchuan,China,Earthquake of 12 May 2008.Seismol.Res.Lett.,2008,79(6) :844～854
[38] Lin J,Stein R S.Stress triggering in thrust and subduction earthquakes,and stress interaction between the southern San Andreas and nearby thrust and strike-slip faults.J.Geophys.Res.,2004,109(B02303)
[39] Okada Y.Internal deformation due to shear and tensile faults in a half-space.Bull.Seismol.Soc.Am.,1992,82:1018～1040
[40] Zhou Y,Nolet G F,Dahlen A,et al.Global upper-mantle structure from finite-frequency surface-wave tomography.J.Geophys.Res.,2006,111(B04304)
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