Short Period Free Oscillation of the Earth Caused by the Chilean Earthquake of May 22, 1960 and Related Problems

Nagamune, Tomeo; Suzuki, Yasuo; Saitô, Masanori

doi:10.4294/jpe1952.12.37

Cited by 5 publications

(1 citation statement)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This finding may be contrasted with the results of an analysis of the Lamont recording of the same earthquake by Alsop (1964a), who was unable to observe organized energy for periods shorter than 200s. Spectral peaks with periods as short as 150s also have been reported for the Chilean shock of 1960 May 22 (Nagamune et al 1964). It may be concluded, therefore, that there is no clear relationship between the duration of an earthquake and the shortest observable period of free oscillations, as had been suggested by Takeuchi, Kanamori 8c Saito (1963).…”

Section: A Dziewonski and M Landismanmentioning

confidence: 69%

Great Circle Rayleigh and Love Wave Dispersion from 100 to 900 Seconds

Dziewoński

Landisman

1970

Geophys J Int

View full text Add to dashboard Cite

37 38 A. Dziewonski and M. LaudIsman first overtone, are similar to dispersion curves for a spherical non-rotating Gutenberg-Bullen A' model. A number of features are common to the deviations of trigonometrically smoothed Rayleigh wave phase velocities derived from (a) the filtered auto-correlograms, (b) the corresponding periodograms, and (c) the free periods compiled by Pekeris in 1966, when these data are subtracted from values calculated for the non-rotating spherical Gutenberg-Bullen A' Earth model. The deviations are negative for T > 500 s, slightly positive for 370 < T < 500s, and again negative for T < 370s. A negative minimum of N 0.025 kms-' occurs for T = 250s, and the present measurements indicate a local decrease in the negative deviations near 180 s. Rayleigh wave group velocity deviations are positive for T > 450 s, and are generally negative for shorter periods with a sharp minimum of N 0.08 km s-l near 325 s and a local maximum near 225 s. Deviations of the trigonometrically smoothed Love wave phase velocities are negative for T > 350s and positive for T < 350s, rising to approximately 0.06 km s-' near 150 s. The corresponding group velocity deviations change from negative to positive as T becomes less than 500-600 s; they then increase continually, reaching II( 0.1 km s-' near 250 s and remaining near this value for periods as short as 100s.The deviations found for T > 225s may well be world-wide phenomena which indicate that revisions will be required at corresponding depths within the Earth, taking proper account of the required corrections for ellipticity and rotation discussed by Dahlen in 1968. Shear velocities lower than those of the Gutenberg distribution will be needed at depths in the vicinity of 200-500km, but alterations of both signs may be required at other depths when all of the data are considered. Short period dispersion, group velocities, overtone measurements and body wave observations should prove useful for this task.(c) the epicentral distance to TAU is very close to 90" (87.4") which is the optimum distance according to the theoretical considerations presented in Section 2A. 58 A. Dziewonski and M. Landisman ORDER I i UMD E R 05 6 0 s 7 0 s 8 05 9 0510 0 5 1 1 0512 0513 0 5 1 4 OS15 0516 0517 0518 0519 0520 0521 0522 0523 0 5 2 4 0525 0526 0527 0528 0 5 2 9 0530 0531 0532 0533 0534 0535 0536 0537 0538 0539 0540 0 5 4 1 0542 0 5 4 3 0544 0545 OS46 0547 0548 0549 0550 0 5 5 1 0552 0553 0 5 5 4 0555 0556 0 5 5 7 0558 0559 0560 0561

show abstract

Section: A Dziewonski and M Landismanmentioning

confidence: 69%

Great Circle Rayleigh and Love Wave Dispersion from 100 to 900 Seconds

Dziewoński

Landisman

1970

Geophys J Int

View full text Add to dashboard Cite

show abstract

Free bodily vibrations of the terrestrial planets

Bolt

Derr

1969

Vistas in Astronomy

View full text Add to dashboard Cite

Contributions of theoretical seismograms to the study of modes, rays, and the Earth

Landisman¹,

Usami²,

Suzuki³

et al. 1970

Reviews of Geophysics

View full text Add to dashboard Cite

Theoretical seismograms, for both simplified and realistic models of the earth, can be calculated and analyzed to learn the relations between free oscillations and traveling waves. These studies can help to clarify the influence of the physical properties of the earth upon the generation, propagation, attenuation, and dispersion of elastic waves. Principal results include the equivalence of mantle and crustal Rayleigh waves to the fundamental radial modes of spheroidal free oscillations a•d the equivalence of G waves and ordinary Love waves to the fundamental radial modes of to,rsional free oscillations. In contrast, the higher radial modes produce all the direct, reflected, refracted, and diffracted body phases, as well as the higher-mode surface waves. Stoneley-wave propagation along the core-mantle boundary introduces a large number of interesting phenomena into the propagation of the spheroidal overtones. The confinement of the Stoneley modes to the vicinity of this boundary is responsible for the discontinuities in the spectra and the relative difficulty in the excitation of long-period P and SV diffracted arrivals, as compared with the corresponding SH phases. The trapping of body-wave energy for sources within a velocity inversion is demonstrated. The particle motion ratio at the surface may be as useful as phase velocity in the understanding of the physical properties beneath a recording site; realistic curves of this parameter are presented for a wide range of periods and radial orders. 1. IN'TRODUC.Y[ 0 N The calculation and study of theoretical seismograms for elastic, gravitating, spherical models of the earth have seen remarkable progress in just the past few years. These studies stem directly from SatS's fundamental observation that, since the sphere is a finite, bounded body, the entire disturbance on the surface of the sphere can be found by an appropriate summation of the contributions from the simple poles corresponding to the free oscillations [Sate, Usami, and Ewing, 1962]. The lack of a half-space in this problem removes the necessity of considering the branch points normally associated with the body waves in most problems of elasticRy [Sat•, Usami, and Ewing,'•1962]. These studies have systematically explored many basic questions in seismology, including the fascinating problem of the relation of modes to waves and •Contribution 152 of the Geosciences Division, University of Texas at Dallas, Texas 75230. 2University of Texas at Dallas, Texas 75230. rays. They have also permitted an improvement in the understanding of the generation, propagation, attenuation, and dispersion of seismic waves as related to the properties of the source, the physical properties of the terrestrial elastic transmission medium, and the recording system. Even though there remain many outstanding problems that are still under study, the authors hope that a synthesis of some of the principal results of this program may serve as an appropriate contribution in honor of l•orman Haskell, one of America's great theoretical ...

show abstract

Short Period Free Oscillation of the Earth Caused by the Chilean Earthquake of May 22, 1960 and Related Problems

Cited by 5 publications

References 2 publications

Great Circle Rayleigh and Love Wave Dispersion from 100 to 900 Seconds

Great Circle Rayleigh and Love Wave Dispersion from 100 to 900 Seconds

Free bodily vibrations of the terrestrial planets

Contributions of theoretical seismograms to the study of modes, rays, and the Earth

Contact Info

Product

Resources

About