Amplitude curves of seismic body waves and the structure of the upper mantle in Europe

Vaněk, J.

doi:10.1016/0040-1951(68)90066-8

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…Studies of amplitudes of P-wave first arrivals (Vanek 1968;Gibowicz 1972) indicate that amplitudes generally decrease fairly steadily with distance until about lo", increase to a maximum near 20" (the so-called ' 20" discontinuity '), and then decrease again (cf. inset to Fig.…”

Section: Fig 1 Ray Pathsmentioning

confidence: 99%

P-Wave Scattering in the Earth's Crust and Upper Mantle

1975

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The codas which follow P-phase onsets on seismic records can be interpreted in terms of waves scattered from random inhomogeneities in the Earth's crust and upper mantle. In particular, the so-called precursors to PP have travel times and slownesses consistent with the interpretation of these signals as waves scattered from direct P-waves incident at the Earth's surface at distances greater than about 20" from either the source or receiver. Significant differences between recordings at the Warramunga array of PP precursors from two Novaya Zemlya explosions are extremely difficult to account for on any interpretation previously suggested, but are fully consistent with the random variations to be expected on the proposed scattering mechanism.The present interpretation accounts for the major observed features of P codas, including their durations and the variations in slowness along the trains. Precursors to P'P' can also be interpreted as scattering phenomena. Thus the interpretation removes the need to postulate sharp reflecting discontinuities in the uppermost few hundred kilometres of the upper mantle.

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Section: Fig 1 Ray Pathsmentioning

confidence: 99%

P-Wave Scattering in the Earth's Crust and Upper Mantle

1975

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“…The left curves are not corrected for the pressure effect, while the right ones are corrected for the effect. is confirmed by gravimetric studies of Renner and Stegena (1966) and by selective migration studies of E. Szadeczky-Kardoss (1967), and further, by the approximate coincidence of the depths of Gutenberg's low velocity layer and that of the conductive layer according to Vanek (1968). Fig.…”

Section: In the Carpathianmentioning

confidence: 61%

Some Results of the Magnetotelluric Survey in the Carpathian Basin and its Complex Interpretation

Ádám

1970

J. geomagn. geoelec

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“…The jump in amplitude commonly observed at about 1000 km in Russia and the United States (Evernden 1967), and at 9'3°in south-eastern Europe corresponds to that at 10'5°-11°in New Zealand. Two further oscillations, with maxima at 13°and 15'4°, have been observed in Asia Minor and in south-eastern Europe (Vanek 1966(Vanek , 1968. These have adequate expression in New Zealand at 14°-15°and 16'5°_17°.…”

Section: Amplitude-distance Curvesmentioning

confidence: 91%

“…The relationship between the amplitude of P waves and epicentral distance has been studied in many other regions (for example, Vanek and Radu 1964;Jordan et al, 1965;Vanek 1966;Evernden 1967;Solovyov and Solovyeva 1967;Sumner 1967;Sutton et al 1967;Antonova et aI. 1968;Vanek 1968;Long and Berg 1969;McGinley and Anderson 1969).…”

Section: Amplitude-distance Curvesmentioning

confidence: 99%

Amplitude ofPwaves recorded at New Zealand stations from shallow earthquakes at less than 30°

Gibowicz¹

1972

New Zealand Journal of Geology and Geophysics

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The dependence of P wave amplitude on distance has been deduced from 1,737 observations of shallow earthquakes recorded at 11 New Zealand stations in the distance range from O· 50 to 30 0 . The curves have a strongly oscillatory character, with maxima at distances believed to coincide with the first arrival of waves refracted from several deep discontinuities. The lateral variations of amplitude reveal a complex pattern of horizontal inhomogeneity in the lower crust and upper mantle, accompanied by changes in velocity and attenuation. Corresponding values of Q range from 100 in the northern half of the North Island to 400 in Fiordland. There appears to be an inverse correlation between the amplitude residuals at the individual stations and the travel-time anomalies, larger amplitudes being associated with early arrivals and vice versa.

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Amplitude curves of seismic body waves and the structure of the upper mantle in Europe

Cited by 8 publications

References 12 publications

P-Wave Scattering in the Earth's Crust and Upper Mantle

P-Wave Scattering in the Earth's Crust and Upper Mantle

Some Results of the Magnetotelluric Survey in the Carpathian Basin and its Complex Interpretation

Amplitude ofPwaves recorded at New Zealand stations from shallow earthquakes at less than 30°

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