| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
GEOSCIENCES DIVISION UNIVERSITY OF TEXAS AT DALLAS, P.O. BOX 30365 DALLAS, TEXAS
BERNARD PRICE INSTITUTE FOR GEOPHYSICAL RESEARCH UNIVERSITY OF WITWATERSRAND, JOHANNESBURG, South Africa
Abstract
Measurements of group velocities by means of band-pass filtering lead to systematic errors when group in velocity changes rapidly with frequency. A new method hereafter referred to as "residual dispersion measurement" avoids this difficulty by transforming the signal prior to the filtering. An observed seismogram is cross-correlated with a theoretical seismogram in which the dispersion approximates the observed dispersion within a few per cent. Dispersion of the resulting pulse can be measured with a much higher precision, since du/d
has been reduced by at least an order of magnitude. In addition, the method can be employed iteratively to obtain a greater precision of measurement.
The dispersion of mantle Rayleigh waves is measured from a sum of 48 auto-correlograms of the recordings of the Alaskan earthquake of March 28, 1964. Group and phase velocities are obtained for order numbers between 0S9 and 0S47. It is estimated that the absolute error of the group-velocity measurement does not exceed 0.015 km/sec.
The analysis of a sum of 13 auto-correlograms of horizontal component seismograms with predominantly transverse motion reveals that the fundamental-mode Love-wave data may be contaminated by higher torsional modes. Comparison of several sets of average Love-wave phase velocities shows a discrepancy of the order of 0.4 per cent in the period range from 350 to 170 sec. The corresponding figure for Rayleigh waves is less by at least an order of magnitude.
Footnotes
* Now at the Department of Geological Sciences, Harvard University, Cambridge, Massachusetts 02138.
This article has been cited by other articles:
|
|
 |
|
  M. Navarro, V. Corchete, J. Badal, J. A. Canas, L. Pujades, and F. Vidal Inversion of Rg waveforms recorded in southern Spain Bulletin of the Seismological Society of America, August 1, 1997; 87(4): 847 - 865. [Abstract] [PDF]
|
|
|
|
 |
|
 P. F. Ihmle, P. F. Ihmle, P. Harabaglia, and T. H. Jordan Teleseismic Detection of a Slow Precursor to the Great 1989 Macquarie Ridge Earthquake Science, July 9, 1993; 261(5118): 177 - 183. [Abstract] [PDF]
|
|
|
|
|
|
A. LEVSHIN, L. RATNIKOVA, and J. BERGER Peculiarities of surface-wave propagation across central Eurasia Bulletin of the Seismological Society of America, December 1, 1992; 82(6): 2464 - 2493. [Abstract] [PDF]
|
|
|
|
|
|
G. PAYO, V. CORCHETE, J. BADAL, F. SERON, J. A. CANAS, and L. PUJADES First two-station Rayleigh-wave velocity measurements for the northern Iberian region Bulletin of the Seismological Society of America, June 1, 1992; 82(3): 1434 - 1452. [Abstract] [PDF]
|
|
|
|
|
|
B. YAN and S. S. ALEXANDER Source mechanism study of the 1982 New Brunswick, Canada, earthquake sequence using combined surface-wave methods Bulletin of the Seismological Society of America, April 1, 1990; 80(2): 296 - 312. [Abstract] [PDF]
|
|
|
|
|
|
D. R. RUSSELL, R. B. HERRMANN, and H.-J. HWANG Application of frequency variable filters to surface-wave amplitude analysis Bulletin of the Seismological Society of America, February 1, 1988; 78(1): 339 - 354. [Abstract] [PDF]
|
|
|
|
|
|
E. A. DEAN The simultaneous smoothing of phase and group velocities from multi-event surface wave data Bulletin of the Seismological Society of America, October 1, 1986; 76(5): 1367 - 1383. [Abstract] [PDF]
|
|
|
|
|
|
S. N. BHATTACHARYA Higher order accuracy in multiple filter technique Bulletin of the Seismological Society of America, October 1, 1983; 73(5): 1395 - 1406. [Abstract] [PDF]
|
|
|
|
|
|
C.-C. FENG and T.-L. TENG An error analysis of frequency-time analysis Bulletin of the Seismological Society of America, February 1, 1983; 73(1): 143 - 155. [Abstract] [PDF]
|
|
|
|
|
|
S. SENEFF A fast new method for frequency-filter analysis of surface waves: Application in the west pacific Bulletin of the Seismological Society of America, August 1, 1978; 68(4): 1031 - 1048. [Abstract] [PDF]
|
|
|
|
|
|
D. C. NYMAN and M. LANDISMAN The display-equalized filter for frequency-time analysis Bulletin of the Seismological Society of America, April 1, 1977; 67(2): 393 - 404. [Abstract] [PDF]
|
|
|
|
|
|
H. K. GUPTA, D. C. NYMAN, and M. LANDISMAN Shield-like upper mantle structure inferred from long-period Rayleigh- and Love-wave dispersion investigations in the Middle East and southeast Asia Bulletin of the Seismological Society of America, February 1, 1977; 67(1): 103 - 119. [Abstract] [PDF]
|
|
|
|
|
|
R. B. HERRMANN Some aspects of band-pass filtering of surface waves Bulletin of the Seismological Society of America, April 1, 1973; 63(2): 663 - 671. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
