福建地区环境噪声瑞利波群速度层析成像
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摘要
本文利用福建、广东、江西和浙江等4省数字地震监测台网中69个宽频带台站2010年4月13日～10月13日的速度型噪声记录和互相关技术,提取两两台站间的瑞利面波格林函数,并利用层析成像技术最终反演获得了福建地区(115.7～120.5°E、23.6～28.35°N)瑞利面波群速度的分布图像。结果表明,利用该方法得到的福建地区周期为3～5s的瑞利面波群速度在2.73～3.17km/s之间,平均速度为2.96km/s。瑞利波群速度横向变化与福建地区地表构造特征和地热异常区分布情况是基本吻合的;该群速度分布图在漳州盆地和福州盆地区域表现出非常明显的低速异常,这主要是因为受到盆地沉积层和高地热的影响;杉岭地块属于山地地形,但由于受到高地热的影响,因此表现为低速异常;永安-玳瑁山地块为山地区,而受到中地热的影响,速度异常表现较为复杂。
The vertical correlation coefficients between two stations at intervals of 1-day arecalculated with the 77 broad-band stations'microseisms records given by the Seismic MonitoringNetwork of Fujian,Guangdong,Jiangxi and Zhejiang Provinces from April 13,2010 to May 10,2010.The authors got the different coefficients and added the interferential coefficients.Based onthe chessboard test in seismology,the authors perform ambient noise tomography of FujianProvince(110° ～ 123° E,21° ～ 31° N) with the appropriate inversion matrix.The results implythat the signal-noise-ratio(SNR) increases proportional to the added times,and the groupvelocity of Rayleigh waves in Fujian Province is between 2.8km /s and 3.2km /s with averagevelocity 3.0km /s.The distribution of the group velocity is almost coincident with the topographyand the geothermy of Fujian Province.But because of the effects of both the topography and thegeothermy,the distribution of the group velocity in some areas is abnormal.From the groupvelocity distribution image,an obvious low velocity area can be found in the area of Zhangzhoubasin and Fuzhou basin.It must be affected by both the sedimentary and the geothermy deposit inthese two basins.
The vertical correlation coefficients between two stations at intervals of 1-day arecalculated with the 77 broad-band stations'microseisms records given by the Seismic MonitoringNetwork of Fujian,Guangdong,Jiangxi and Zhejiang Provinces from April 13,2010 to May 10,2010.The authors got the different coefficients and added the interferential coefficients.Based onthe chessboard test in seismology,the authors perform ambient noise tomography of FujianProvince(110° ～ 123° E,21° ～ 31° N) with the appropriate inversion matrix.The results implythat the signal-noise-ratio(SNR) increases proportional to the added times,and the groupvelocity of Rayleigh waves in Fujian Province is between 2.8km /s and 3.2km /s with averagevelocity 3.0km /s.The distribution of the group velocity is almost coincident with the topographyand the geothermy of Fujian Province.But because of the effects of both the topography and thegeothermy,the distribution of the group velocity in some areas is abnormal.From the groupvelocity distribution image,an obvious low velocity area can be found in the area of Zhangzhoubasin and Fuzhou basin.It must be affected by both the sedimentary and the geothermy deposit inthese two basins.
引文
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朱金芳,2008,闽南地区城市活动构造与地震,北京:科学出版社。
Aki K,1957,Space and time spectra of stationary stochastic waves with special reference to microtremors,Bull Earthquake Res InstUniv,Tokyo,35,415～456.
Barmin M P,Ritzwoller M H,Levshin A L,2001,A fast and reliable method for surface wave tomography,Pure Appl Geopys,1351～1375.
Claerbout J F,1968,Synthesis of a layered medium from its acoustic transmission response,Geophysics,33,264～269.
Duvall T,Jefferies S,Harvey J,et al,1993,Time distance helioseismology,Nature,362,430～432.
Leveque J,Rivera L,Wittlinger G,1993,On the use of the checkerboard test to assess the resolution of tomographic inversion,Geophys J Int,115,313～318.
Lin F C,Ritzwoller M H,Townend J,et al,2007,Ambient noise Rayleigh wave tomography of New Zealand,Geophys J Int,170(2),649～666.
Lobkis O I,Weaver R L,2001,On the emergence of the Green’s function in the correlations of a diffuse field,J Acoust Soc Am,110(6),3011～3017.
Sabra K G,Gerstoft P,Roux P,et al,2005,Extracting time-domain Green’s function estimates from ambient seismic noise,Geophys Res Lett,32,L03310,doi:10.1029/2004GL021862.
Shapiro N M,Campillo,2004,Emergence of broadband Rayleigh waves from correlations of the ambient seismic noise,Geophys ResLet,31,L07614,doi:10.1029/2004GL019491.
Shapiro N M,Campillo,Stehly L,et al,2005,High-resolution surface wave tomography from ambient seismic noise,Science,307,1615～1618.
Yanovskaya T B,Ditmar P G,1990,Smoothness criteria in surface wave tomography,Geophys J Geophys J Int,102,63～72.
Yao H R,Hilst V,Hoop M V,2006,Surface-wave array tomography in SE Tibet from ambient seismic noise and two-stationanalysis-I.Phase velocity maps,Geophys J Int,166,732～744.
李军、金星、周峥嵘等,2009,利用地震噪声准实时监测短周期面波波速变化,地震学报,31(6),629～640。
朱金芳,2008,闽南地区城市活动构造与地震,北京:科学出版社。
Aki K,1957,Space and time spectra of stationary stochastic waves with special reference to microtremors,Bull Earthquake Res InstUniv,Tokyo,35,415～456.
Barmin M P,Ritzwoller M H,Levshin A L,2001,A fast and reliable method for surface wave tomography,Pure Appl Geopys,1351～1375.
Claerbout J F,1968,Synthesis of a layered medium from its acoustic transmission response,Geophysics,33,264～269.
Duvall T,Jefferies S,Harvey J,et al,1993,Time distance helioseismology,Nature,362,430～432.
Leveque J,Rivera L,Wittlinger G,1993,On the use of the checkerboard test to assess the resolution of tomographic inversion,Geophys J Int,115,313～318.
Lin F C,Ritzwoller M H,Townend J,et al,2007,Ambient noise Rayleigh wave tomography of New Zealand,Geophys J Int,170(2),649～666.
Lobkis O I,Weaver R L,2001,On the emergence of the Green’s function in the correlations of a diffuse field,J Acoust Soc Am,110(6),3011～3017.
Sabra K G,Gerstoft P,Roux P,et al,2005,Extracting time-domain Green’s function estimates from ambient seismic noise,Geophys Res Lett,32,L03310,doi:10.1029/2004GL021862.
Shapiro N M,Campillo,2004,Emergence of broadband Rayleigh waves from correlations of the ambient seismic noise,Geophys ResLet,31,L07614,doi:10.1029/2004GL019491.
Shapiro N M,Campillo,Stehly L,et al,2005,High-resolution surface wave tomography from ambient seismic noise,Science,307,1615～1618.
Yanovskaya T B,Ditmar P G,1990,Smoothness criteria in surface wave tomography,Geophys J Geophys J Int,102,63～72.
Yao H R,Hilst V,Hoop M V,2006,Surface-wave array tomography in SE Tibet from ambient seismic noise and two-stationanalysis-I.Phase velocity maps,Geophys J Int,166,732～744.
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