- Open Access
Surface wave analysis with beamforming
Earth, Planets and Space volume 59, pages 453–458 (2007)
It is well known that off-great-circle path propagation causes a technical difficulty for surface wave analysis in higher frequency ranges. We propose a new approach that combines a beamforming technique and two-station phase velocity measurement to resolve this problem. Beamforming allows us to determine the correct azimuth of incoming surface waves which can be taken into account in phase velocity measurement. Beamforming results also support that a plane-wave approximation is mostly acceptable for frequencies up to about 50–60 mHz (millihertz), although evidence of multipathing is occasionally recognized in beamforming results as multiple peaks. Application of this correction scheme for Rayleigh-wave data in Southern California seems to make the largest impact on the results of azimuthal anisotropy. Effects are not large for frequencies up to 30 mHz but fast velocity axes in azimuthal anisotropy maps change significantly for higher frequencies.
Aki, K. and P. G. Richards, Quantitative Seismology, W. H. Freeman and Company, San Francisco, 1980.
Baumont, D., A. Paul, G. Zandt, S. Beck, and H. Pedersen, Lithospheric structure of the central Andes based on surface wave dispersion, J. Geophys. Res., 107 B12, 2371, doi:10.1029/2001JB000345, 2002.
Bourova, E., I. Kassaras, H. A. Pedersen, T. Yanovskaya, and D. Hatzfeld, Constraints o absolute S velocities beneath the Aegean Sea from surface wave analysis, Geophys. J. Int., 160, 1006–1019, doi:10.1111/j.1365-246X.2005.02565.x, 2005.
Bruneton, M., V. Farra, H. A. Pedersen, and teh SVEKALAPKO Seismic Tomography Working Group, Non-linear surface wave phase velocity inversion based on ray theory, Geophys. J. Int., 151, 583–596, 2002.
Cotte, N., H. A. Pedersen, M. Campillo, V. Farra, and Y. Cansi, Off-greatcircle propagation of intermediate-period surface waves observed on a dense array in the French Alps, Geophys. J. Int., 142, 825–840, 2000.
Friedrich, W., E. Wielandt, and S. Strange, Non-plane geometries of seismic surface wavefields and their implications for regional surface wave tomography, Geophys. J. Int., 119, 931–948, 1994.
Johnson, Don H. and D. E. Dudgeon, Array Signal Processing, P T R Prentice-Hall Inc., Upper Saddle River, New Jersey, 1993.
Laske, G. and G. Masters, Constraints on global phase velocity maps by long-period polarization data, J. Geophys. Res., 101 B7, 16059–16075, 1996.
McGarr, A., Amplitude variations of Rayleigh waves—Across a continental margin, Bull. Seism. Soc. Am., 59, 1281–1305, 1969a.
McGarr, A., Amplitude variations of Rayleigh waves—Horizontal refraction, Bull. Seism. Soc. Am., 59, 1307–1334, 1969b.
Pedersen, H. A., Impacts of non-plane waves on two-station measurements of phase velocities, Geophys. J. Int., 165, 279–287, doi:10.1111/j.1365-246X.2006.02893.x, 2006.
Pollitz, F., Regional velocity structure in nortehrn California from inversion of scattered seismic surface waves, J. Geophys. Res., 104,B7, 15043–15072, 1999.
Prindle, K., Souther California Surface Wave Analysis: Recovery of Three-dimensional S-wave Velocity Structure, the Finite Frequency, Off Great-Circle Propagation and Azimuthal Anisotropy, Ph.D. thesis, University of California, Santa Barbara, 2006.
Prindle, K. and T. Tanimoto, Teleseismic Surface Wave study for S-wave velocity structure under an array: Southern California, Geophys. J. Int., 166, 601–621, 2006.
Tanimoto, T. and Don L. Anderson, Lateral Heterogeneity and Azimuthal Anisotropy of the Upper Mantle: Love and Rayleigh Waves 100–250s, J. Geophys. Res., 90, 842–1858, 1985.
Tanimoto, T. and K. Prindle, Three-dimensional S-wave velocity structure in Southern California, Geophys. Res. Lett., 29, 8, 1–4, doi:1029/ 2001GL013486, 2002.
Tape, C., Q. Liu, and J. Tromp, Finite-frequency tomography using adjoint methods—Methodology and examples using membrane surface waves. Geophys. J. Int., 2006 (in press).
Yang, Y. and D. W. Forsyth, Rayleigh wave phase velocitiers, small-scale convection, and azimuthal anisotropy beneath souther California, J. Geophys. Res., 111, B07306, doi:10.1029/2005JB004180, 2006.
Zhao, L. and T. Jordan, STructural sensitivity of finite-frequency seismic waves: A full-wave approach, Geophys. J. Int., 165, 981–990, 2006.
About this article
Cite this article
Tanimoto, T., Prindle, K. Surface wave analysis with beamforming. Earth Planet Sp 59, 453–458 (2007). https://doi.org/10.1186/BF03352706
- Surface wave
- wave propagation
- earth structure