pure and applied geophysics

, Volume 104, Issue 1, pp 439–452 | Cite as

Dependence of theP-wave amplitude spectrum on focal depth

  • Hamid N. Al-Sadi


Four spectral parameters, each of which reflects a certain spectral characteristic, are computed for 67 power spectra of earthquakes. The analyzed signals used in this work are theP-phases recorded by short-period, vertical-component seismographs.

In correlating the values of the spectral parameters with the respective focal depths, a qualitative ‘spectrum-depth’ relation is obtained. The most outstanding feature of the relationship thus computed, is a pronounced anomaly in the depth-range of 50–250 km. This is found to correlate rather well with the location of the low-velocity layer which many seismologists have shown to exist in the earth's upper mantle. With the aid of results obtained from experimental work on rock blasts, it is argued that the anomalous zone has more viscous character than the overlying and underlying media.


Power Spectrum Experimental Work Spectral Characteristic Analyze Signal Spectral Parameter 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    T. Asada andK. Takano,Attenuation of short period P-waves in the mantle, J. Phys. Earth11 (1963), 25.Google Scholar
  2. [2]
    M. Båth,Some consequences of the existence of low-velocity layers, Ann. Geofis.9 (1956), 441.Google Scholar
  3. [3]
    M. Båth,Lateral inhomogeneities of the upper mantle, Tectonophysics,2 (1965), 483.Google Scholar
  4. [4]
    J. Dorman, M. Ewing andJ. Oliver,Study of shear-velocity distribution in the upper mantle by mantle Rayleigh waves, Bull. Seism. Soc. Am.50 (1960), 87.Google Scholar
  5. [5]
    M. A. Enayatollah,Travel times of P-waves for the Swedish-Finnish seismograph network, Pure and Appl. Geophys.94 (1972), 101.Google Scholar
  6. [6]
    M. A. Enayatollah,Continental-array measurements of P-wave velocities in the mantle, Pure and Appl. Geophys.94 (1972), 136.Google Scholar
  7. [7]
    B. Gutenberg,Attenuation of seismic waves in the earth's mantle, Bull. Seism. Soc. Am.48 (1958), 269.Google Scholar
  8. [8]
    N. V. Kondorskaya, L. N. Pavlov, A. N. Pustovitenko andS. L. Solov'ev,Some results of a study of the longitudinal-wave spectra from earthquakes in the Far East, Izv. Acad. Sci. USSR, Phys. Solid Earth No. 1 (1967), 36 (Engl. ed.).Google Scholar
  9. [9]
    B. Mohammadioun,Structure du manteau supérieur et spectres d'énergie des ondes longitudinales, C.R. Acad. Sc. Paris.,261 (1965), 4472.Google Scholar
  10. [10]
    E. A. Robinson,Multichannel Time Series Analysis with Digital Computer Programs (Holden-Day, Inc., San Francisco, 1967).Google Scholar
  11. [11]
    S. L. Solov'ev andA. N. Pustovitenko,On the possible reduction in period of longitudinal waves as the depth of the earthquake focus increases, Izv. Acad. Sci. USSR, Geophys. Ser., No. 6 (1964), 508 (Engl. ed.)Google Scholar
  12. [12]
    M. Tsujiura,Frequency analysis of seismic waves (1), Bull. Earthq. Res. Inst. (Tokyo)44 (1966), 873.Google Scholar
  13. [13]
    M. Tsujiura,Frequency analysis of seismic waves (2), Bull. Earthq. Res. Inst. (Tokyo)45 (1967), 973.Google Scholar
  14. [14]
    M. Tsujiura,Regional variation of P-wave spectrum (1), Bull. Earthq. Res. Inst. (Tokyo)47 (1969), 613.Google Scholar

Copyright information

© Birkhäuser Verlag 1973

Authors and Affiliations

  • Hamid N. Al-Sadi
    • 1
  1. 1.Seismological InstituteUppsala 1Sweden

Personalised recommendations