水中甚低频声源激发海底地震波的传播
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摘要
目前关于海底地震波的理论分析仅局限于水平分层的弹性海底,该文对倾斜弹性海底的地震波传播规律进行研究.研究了浅海海底地震波的激发机理,当海底为弹性海底,且海底切变波速度大于水中声速时,水中声源能激发出水中的波导简正波和Scholte波、弹性海底的次表面波和Scholte波.建立预报海底地震波场的抛物方程方法模型,研究了海底地震波的传播规律:甚低频声波在具有倾斜弹性海底的海洋环境中传播时,水中波导简正波和海底的次表面波会随着海水深度的减小出现能量泄漏现象.
At present,theoretical analysis of the bottom seismic wave have been limited to dealing with a horizontal layered elastic bottom.A more detailed understanding would allow more accurate modeling of the interactions of seismic waves with the ocean bottom.The mechanisms promoting seismic wave propagation in shallow water were studied.With an elastic ocean bottom and a shear wave larger than the speed of sound it was found that all four cases,the normal modes in water and the Scholte waves in water,as well as the sub-interface waves and the Scholte waves were excited by low frequency sources in shallow water.An elastic parabolic approximation method for calculating seismic waves was developed.A field distribution rule for seismic waves was also analyzed.In wedge shaped basins with an elastic bottom,the energy of the normal modes in water as well as that of sub-interface waves will experience leakage as water depth decreased.
At present,theoretical analysis of the bottom seismic wave have been limited to dealing with a horizontal layered elastic bottom.A more detailed understanding would allow more accurate modeling of the interactions of seismic waves with the ocean bottom.The mechanisms promoting seismic wave propagation in shallow water were studied.With an elastic ocean bottom and a shear wave larger than the speed of sound it was found that all four cases,the normal modes in water and the Scholte waves in water,as well as the sub-interface waves and the Scholte waves were excited by low frequency sources in shallow water.An elastic parabolic approximation method for calculating seismic waves was developed.A field distribution rule for seismic waves was also analyzed.In wedge shaped basins with an elastic bottom,the energy of the normal modes in water as well as that of sub-interface waves will experience leakage as water depth decreased.
引文
[1]陈云飞,吕俊军,于沨.航行舰船地震波及其在水中目标探测中的应用[J].舰船科学与技术,2005,27(3):62-66.CHEN Yunfei,L Junjun,YU Feng.The ship inducedseismic wave and its application in the underwater target de-tection[J].Ship Science and Technology,2005,27(3):62-66.
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[10]DOLGIKHG I,VALENTIN D I,DOLGIKH S G,et al.Application of horizontally and vertically oriented strainme-ters in geophysical studies of transitional zones[J].Iz-vestiya Physics of the Solid Earth,2002,38(8):686-689.
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[12]卢再华,张志宏,顾建俊.浅海低频点声源作用下海底地震波的数值模拟[J].武汉理工大学学报,2007,3(4):607-610.LU Zaihua,ZHANG Zhihong,GUO Jiannong.Numericalsimulation of seafloor seismic wave caused by low frequen-cy point sound source in shallowwater[J].Journal of Wu-han University of Technology,2007,31(4):607-610.
[13]卢再华,张志宏,顾建俊.舰船海底地震波形成机理的理论分析[J].应用力学学报,2007,24(1):54-57.LU Zaihua,ZHANG Zhihong,GUO Jiannong.Theoreticalanalysis to mechanism of seafloor seismic wave induced bysailing vessel[J].Chinese Journal of Applied Mechanics,2007,24(1):54-57.
[14]李响,颜冰.舰船地震波场分析[J].噪声与振动控制,2007,27(4):120-122.LI Xiang,YANBing.Wavelet spectrumanalysis of ship seis-mic-wave field[J].Noise and Vibration Control,2007,27(4):120-122.
[15]杨士莪.Theory of underwater sound propagation[M].哈尔滨:哈尔滨工程大学出版社,2009:24-27.
[16]OUTING D A.Parabolic equation methods for range de-pendent layered elastic media[D].Troy:RensselaerPolytechnic Institute.2004:12.
[17]JERZAK W.Parabolic equation for layered elastic media[D].Troy:Rensselaer Polytechnic Institute.2001:30-34.
[18]COLLINS M D,DACOL D K.A mapping approach forhandling sloping interfaces[J].J Acoust Soc Am,2000,107(4):1937-1942.
[2]RAUCHD.Seismic interface waves in coastal waters:a re-view.SACLANTCEN Report SR-42[R].La Spezia:NATOSACLANTUndersea Research Centre,1980.
[3]DORMAN L M,SAUTER A W.Short-range seismoacousticpropagation on and off the beach[J].Journal of the Acous-tical Society of America,1995,98(5):2971-2971.
[4]SUTTON G H.ULF/VLF ocean bottom seismo-acoustics.AD-A218 810/0/XAB[R].[S.l.],1990:30.
[5]BROCHER T M,IWATAKE B T,GETTBUST JF,et al.Comparison of the S/N ratios of low-frequency hydrophonesand geophones as a function of ocean depth[J].Bulletin ofthe Seismological Society of America,1981,71(5):1649-1659.
[6]SPAIND,HODGKISS W S.Comparison of swallowfloat,o-cean bottom seismometer,sonobuoy data in the VLF(verylow frequency)band.Technical memo.AD-A201 977/6/XAB;MPL-TM-404,MPL-U-32/88[R].[S.l.],1988:561.
[7]TENCATE J A.Beamforming on seismic interface waveswith an array of geophones on the shallow sea floor[J].IEEE Journal of Oceanic Engineering,1995,20(4):300-310.
[8]DOLGIKHG I.Experimental investigations of seismoacous-tic signals excited by a low-frequency hydroacoustic source[J].Acoustical Physics,1998,44(3):301-304.
[9]AVERBAKHV S,BOGOLYUBOV B N.Application of hy-droacoustic radiators for the generation of seismic waves[J].Acoustical Physics,2002,48(2):149-155.
[10]DOLGIKHG I,VALENTIN D I,DOLGIKH S G,et al.Application of horizontally and vertically oriented strainme-ters in geophysical studies of transitional zones[J].Iz-vestiya Physics of the Solid Earth,2002,38(8):686-689.
[11]DAVYDOV A V,DOLGIKH G I.Acoustic monitoring ofthe ocean land transition zone using the laser deformograph[J].Akusticheskij Zhurnal,1994,40(3):466-467.
[12]卢再华,张志宏,顾建俊.浅海低频点声源作用下海底地震波的数值模拟[J].武汉理工大学学报,2007,3(4):607-610.LU Zaihua,ZHANG Zhihong,GUO Jiannong.Numericalsimulation of seafloor seismic wave caused by low frequen-cy point sound source in shallowwater[J].Journal of Wu-han University of Technology,2007,31(4):607-610.
[13]卢再华,张志宏,顾建俊.舰船海底地震波形成机理的理论分析[J].应用力学学报,2007,24(1):54-57.LU Zaihua,ZHANG Zhihong,GUO Jiannong.Theoreticalanalysis to mechanism of seafloor seismic wave induced bysailing vessel[J].Chinese Journal of Applied Mechanics,2007,24(1):54-57.
[14]李响,颜冰.舰船地震波场分析[J].噪声与振动控制,2007,27(4):120-122.LI Xiang,YANBing.Wavelet spectrumanalysis of ship seis-mic-wave field[J].Noise and Vibration Control,2007,27(4):120-122.
[15]杨士莪.Theory of underwater sound propagation[M].哈尔滨:哈尔滨工程大学出版社,2009:24-27.
[16]OUTING D A.Parabolic equation methods for range de-pendent layered elastic media[D].Troy:RensselaerPolytechnic Institute.2004:12.
[17]JERZAK W.Parabolic equation for layered elastic media[D].Troy:Rensselaer Polytechnic Institute.2001:30-34.
[18]COLLINS M D,DACOL D K.A mapping approach forhandling sloping interfaces[J].J Acoust Soc Am,2000,107(4):1937-1942.
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