Q Distribution for Long-Period P Waves in the Mantle

Mikumo, Takeshi; Kurita, Tuneto

doi:10.4294/jpe1952.16.11

Cited by 28 publications

(14 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A large number of long-period P-wave data used in this study generally give support to the SL8 Q model (ANDERSON and HART, 1978 b), as an average Q model down to the lower mantle, which indicates a possible low-Q zone at the coremantle boundary (TENG, 1968;MIKUMO and KURITA, 1968).…”

Section: Comparison Of the Differential Attenuation With The Travel-tsupporting

confidence: 57%

“…The Q distribution with depth over the whole mantle has been closely investigated on the basis of earth's free oscillation and surface wave attenuation data (e.g., ANDERSON and ARCHAMBEAU, 1964;ANDERSON et al, 1965;SAILOR and DZIEWONSKI, 1978) and also from body wave data (e.g., TENG, 1968;MIKUMO and KURITA, 1968). Recently, ANDERSON and HART (1978 a, b) have proposed several, probable models which could satisfy each of the three kinds of attenuation data, that is, free oscillation, surface wave, and body wave data.…”

Section: Introductionmentioning

confidence: 99%

“…Many studies using the spectral-ratio method have yielded rather widely scattered Q-values, which may be attributed partly to their regional variations and partly to the above source and some unidentifiable effects (e.g., MIKUMO and KURITA, 1968 By the damped least squares method (LEVENBERG, 1944), we solve these observational equations for the unknown vector m, whose elements are differential attenuation beneath the stations, the terms relating to events, and the coefficients of epicentral distance-dependent function. The estimate of m, which is represented by m, is written as,…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Global distribution of long-period P-wave attenuation and its tectonic implications.

Mikami

Hirahara

1981

J,Phys,Earth

View full text Add to dashboard Cite

A large number of WWSSN long-period P-wave records from 41 intermediate-and deep-focus earthquakes have been analyzed aiming at investigating global variations of attenuative properties in the upper mantle, with statistical treatments using a damped least squares method. The present results reveal significant regional variations of attenuation over the world. High Q is observed along the Pacific coastal region and the eastern part of the United States, India, Indochina, and Australia, most of which are located in stable shield region. On the other hand, low Q is observed in the western United States and a part of Europe, which are in tectonically active region. There appears to be some correlation between the obtained differential attenuation and heat flows, suggesting that high heat flow regions are characterized by low Q and vice versa. However, there is no clear relation between travel-time residuals and attenuation. A large number of the data used in this study generally give support to the SL8 model as an average Q model in the earth's mantle.

show abstract

Section: Comparison Of the Differential Attenuation With The Travel-tsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Global distribution of long-period P-wave attenuation and its tectonic implications.

Mikami

Hirahara

1981

J,Phys,Earth

View full text Add to dashboard Cite

show abstract

“…An example of the P-wave data is shown in fig. 2 of Mikumo & Kurita (1968). Stations at all azimuths from 30" to 90" were checked to ensure similarity in P and S waveforms in order to avoid excessive source complexity.…”

Section: P D a T Amentioning

confidence: 99%

“…This selectivity is necessary for analysis of amplitude trends in the time domain, as it minimizes the effects of source complexity and radiation pattern, which can otherwise only be limited by utilizing very large data sets. Analysis of long-period WWSSN body wave spectra indicate regional variations in attenuation of A tp* = 7.0 s (Solomon & Toksoz 1970;Mikumo & Kurita 1968;Teng 1968). The resulting At* values differ from, and exceed, those determined at short periods.…”

mentioning

confidence: 99%

Body wave amplitude patterns and upper mantle attenuation variations across North America

Lay

Helmberger

1981

Geophys J Int

View full text Add to dashboard Cite

A broad band amplitude study of P-and SH-waves from deep South American events recorded at WWSSN stations in the United States provides constraints on upper mantle variations in attenuation. The events were selected to minimize contamination due to source complexity, radiation pattern, and source structure. The prevalent feature in the short-and longperiod bands is that the SH amplitudes show the same regional variations as the P amplitudes, with the regional variations of short periods being similar, but enhanced relative to the variations at long periods. The amplitudes show some systematic regional difference between the East Coast and Rocky Mountain provinces, and both short and long periods are enhanced at the Gulf Coast and midwestern stations, probably due to thick sedimentary bed receiver structure. Since detailed receiver structures for individual stations are poorly known, we used the working hypothesis that the regional amplitude patterns are caused by lateral variations in upper mantle attenuation. Both a constant Q and a frequency-dependent attenuation operator were considered, with the relative amplitudes and waveforms in short-and long-period bands used to estimate the acceptable range of At* in the constant Q model, or the acceptable range of the parameter r, , which describes the high-frequency roll-off of the absorption band in the frequency-dependent model. Time domain modelling indicates that the short-period P and SH amplitudes and waveforms in the 1-10s period range do not unambiguously demand frequency-dependent attenuation, allowing for the uncertainty in source frequency content and long-period absorption band amplitude. The short-period P amplitudes can be fit with a range in At; = 0.5 s or a range in r, from 0.001 to 0.25s, with either single parameter variation consistent with the general short-period SH amplitude behaviour. A technique for determining the absolute value of t* and possible r, values appropriate for the 5-20s band was applied to selected data. A value of t* = 0.8 s and small 7 , were found for travel paths from the deep events to North America, and lower t* or large r,, values were found for paths to southern African stations. Longperiod amplitude variations cannot be explained by frequency-dependent 692 T. Lay and D. K Helmberger models with only a single high-frequency roll-off of the absorption band, but values of At; determined from the long-period SH amplitudes do exceedingly well in predicting the long-period P amplitudes under the assumptions of constant Q and t z / t z = 4.0. The total range in long-period At; is about 3 to 4 s. Though receiver effects may cause some of this variation between stations, the data make it clear that such effects must produce amplitude behaviour similar to that caused by regional variations in attenuation. It is shown that the At; values determined from the long periods do not predict the shortperiod amplitudes in detail, but the predictions are not prohibitively outside the range of the short-period amplitude variations. Spectral a...

show abstract

The amplitude ratioPcP/P and the core-mantle boundary

Ibrahim¹

1971

PAGEOPH

View full text Add to dashboard Cite

Q Distribution for Long-Period P Waves in the Mantle

Cited by 28 publications

References 16 publications

Global distribution of long-period P-wave attenuation and its tectonic implications.

Global distribution of long-period P-wave attenuation and its tectonic implications.

Body wave amplitude patterns and upper mantle attenuation variations across North America

The amplitude ratioPcP/P and the core-mantle boundary

Contact Info

Product

Resources

About