Main Article Content
A stacking technique is applied to measure phase velocities of the fundamental and several higher Rayleigh modes over an array of long period stations located in Western Europe. The higher mode dispersion has been measured for periods between 25 and 100 s and for phase velocities up to 7.5 km/s. Using Backus-Gilbert inversion, a detailed model for the shear wave velocity in the upper mantle under the array is obtained. The low velocity zone is located between 150 and 230 km depth and is not very pronounced, but it is preceded by a rise in S velocity around 120 km depth. Strong velocity gradients are found at depths of 360 and 520 km. A good fit to the data can only be obtained if a zone of low density is assumed at a depth of 220 km or there about. As yet little can be said about depth, shape and extent of this zone, but the magnitude of the density drop implies a chemical or mineralogical stratification. A mechanism based on eclogite fractionation (Press, 1969) appears to be a likely candidate as the cause for such a gravitationally unstable stratification.
Authors who publish with this journal as of Vol. 63 agree to the following terms:
a. Authors share the copyright with this journal in equal parts (50% to the journal, 50% to the lead author), and grant the journal right of first publication, with the work after publication simultaneously licensed under Creative Commons Attribution License CC BY-NC-ND 4.0 that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
b. Authors may enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal, and a reference to this copyright notice.
c. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) during the submission process, as this can lead to productive exchanges and earlier and greater citation of published work and better sales of the copyright.
Authors retain copyright and grant the Journal of Geophysics right of first publication, with the work two years after publication simultaneously licensed under the Creative Commons BY-NC-ND 4.0 License that allows others to share the work (with an acknowledgment of the work's authorship and initial publication in this journal), except for commercial purposes and for creating derivatives.
Authors can enter into separate, additional, but non-commercial contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository, but not publish it in a book), with an acknowledgment of its initial publication in this journal.
Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) before and during the submission process, as that can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
This journal is one of a handful of scholarly journals that publish original scientific works under CC BY-NC-ND 4.0 - the only Creative Commons license affording the authors' intellectual property absolute worldwide protection.
Journal of Geophysics is published under the scholar-publishers model, meaning authors do not surrender their copyright to us. Instead, and unlike corporate publishers like Elsevier or Springer Nature that resell copyright to third-parties for up to $80,000 (per paper, per transaction!), the Journal of Geophysics authors share copyright equally with this journal.
Therefore, all the proceeds from reselling copyright to third parties get shared to equal parts (50% to the journal, 50% to the lead author). Under the Berne Convention, this protection is an inheritable right that lasts for as long as the rightsholder lives + 50 years.
By submitting to this journal, the lead author, on behalf of all co-authors, grants permission to this journal to represent all co-authors in negotiating copyright sales and collecting proceeds. The lead author should negotiate with his/her co-authors the modalities of distributing the lead author's portion of the proceeds. Usually, this is per pre-agreed percentage of each co-author's contribution to creating the copyrighted work. (more...)
Anderson, D.L., Hart, R.S. (1976) An Earth model based on free oscillations and body waves. J. Geophys. Res. 81:1461
Backus, G., Gilbert, F. (1970) Uniqueness in the inversion of inaccurate gross Earth data. Phil. Trans. Roy. Soc. London Ser. A266:123
Bath, M. (1976) Average crustal structure of Sweden. Pure Appl. Geophys. 88, 75, 1971 Cara, M.: Observations d'ondes Sa de type SH. Pure Appl. Geophys. 114:141
Clark, S.P., Ringwood, A.E. (1964) Density distribution and constitution of the mantle. Rev. Geophys. 2:35
Crampin, S. (1964) Higher modes of seismic surface waves: Phase velocities across Scandinavia. J. Geophys. Res. 69:4801
Crampin, S. (1967) Coupled Rayleigh-Love second modes. Geophys. J. 12:229
Der, Z.A., Landisman, M. (1972) Theory for errors, resolution and separation of unknown variables in invers problems, with applications to the mantle and crust of Southern Africa and Scandinavia.
Geophys. J. 27:137
Dziewonski, A.M., Hales, A.L. (1972) Numerical analysis of dispersed seismic waves. Methods in Computational Physics 11:39
Elzasser, W.M. (1971) Sea floor spreading as thermal convection. J. Geophys. Res. 76:1101
Fagerness, V., Kanestrom, R. (1973) Variations in upper mantle structure as derived from Pn and Sn waves. Pure and Appl. Geophys. 109:1762
Forsyth, D.W. (1975) A new method for the analysis of multi-mode surface wave dispersion: Application to Love wave propagation in the East Pacific. Bull. Seism. Soc. Am. 65:323
Gilbert, F. (1971) Ranking and winnowing gross Earth data for inversion and resolution. Geophys. J. 23:125
Gilbert, F., Dziewonski, A.M. (1975) An application of normal mode theory to the retrieval of structural parameters and source mechanisms from seismic spectra. Phil. Trans. Roy Soc. London 278:187
Green, D.H., Ringwood, A.E. (1970) Mineralogy of peridotite compositions under upper mantle conditions. Phys. Earth Planet. Interiors 3:359
Hirn, A., Steinmetz, L., Kind, R., Fuchs, K. (1973) Long range profiles in W. Europe: IL Fine structure of the lower lithosphere in France (Southern Bretagne). Z. Geophys. 39:363
Hsi-Ping Liu, Anderson, D.L., Kanamori, H. (1976) Velocity dispersion due to anelasticity; implications for seismology and mantle composition. Geophys. J. (In press)
Ito, K., Kennedy, G.C. (1971) An experimental study of the basalt-garnet granulite-eclogite transition. In: Heacock, J.G. (Ed.) The structure and physical properties of the Earth's crust, Geophys. Monogr. Ser. 14, Washington
Jackson, D.D. (1972) Interpretation of inaccurate, insufficient and inconsistent data. Geophys. J. 28:97
Jacoby, W.R. (1970) Instability in the Upper Mantle and global plate movements. J. Geophys. Res. 75:5671
Knopoff, L. (1972) Observation and inversion of surface wave dispersion. Tectonophysics 13:497
Kovach, R.L. (1965) Seismic surface waves: Some observations and recent developments. Phys. Chem. Earth 6:251
Lehmann, I. (1961) Sand the structure of the upper mantle. Geophys. J. 4:124
Mayer-Rosa, D., Mueller, St. (1973) The gross velocity depth distribution of P and S waves in the upper mantle of Europe from earthquake observations. Z. Geophys. 39:395
Mendiguren, J.A. (1973) Identification of free oscillation spectral peaks for 1970 July 31, Colombian deep shock using the excitation criterion. Geophys. J. 33:281
Nolet, G. (1975) Higher Rayleigh modes in Western Europe. Geophys. Res. Letters 2:60
Nolet, G. (1976) Higher modes and the determination of upper mantle structure. Ph.D. thesis, Utrecht
Nolet, G., Panza, G.F. (1976) Array analysis of seismic surface waves: Limits and possibilities. Pure Appl. Geophys. 114:775
Payo, G. (1964) Crustal phases across the Iberian Peninsula region. Ann. di Geophys. 17:523
Payo, G. (1964) Iberian peninsula crustal structure from surface wave dispersion. Bull. Seism. Soc. Am. 55:727
Press, F. (1968) Earth models obtained by Monte Carlo inversion. J. Geophys. Res. 73:5223
Press, F. (1969) The suboceanic mantle. Science 165:174
Press, F. (1970) Earth models consistent with geophysical data: Phys. Earth Planet. Interiors 3:3
Press, F. (1972) The Earth's interior as inferred from a family of models. In: Robertson, E.C. (Ed.) The nature of the solid Earth. McGraw-Hill, New York
Randall, M.J. (1976) Attenuative dispersion and frequency shift of the Earth's free oscillations. Phys. Earth Planet. Interiors 12:P1
Sapin, M., Prodehl, C. (1973) Long Range profiles in Western Europe I-crustal structure between Bretagne and the central Massif of France. Ann. Geophys. 29:127
Schubert, G., Turcotte, D.L. (1972) One-dimensional model of shallow-mantle convection. J. Geophys. Res. 77:945
Seidl, D. (1971) Spezielle Probleme der Ausbreitung Seismischer Obenflachenwellen mit Beobachtungsbeispielen aus Europa. Thesis, Karlsruhe
Steinmetz, L., Hirn, A., Perrier, G. (1974) Reflexions seismiques a la base de l'asthenosph6re. Ann. Geophys. 30:173
Vlaar, N.J. (1975) The driving mechanism of plate tectonics: a qualitative approach. In: Borradaile, G.J. et al. (Eds.) Progress in geodynamics, Amsterdam
Vlaar, N.J., Wortel, R. (1976) Lithospheric aging, instability and subduction. Tectonophysics 32:331
Wiggins, R.A. (1972) The general linear inverse problem: implication of surface waves and free oscillations for Earth structure Rev. Geophys. Space Phys. 10:251