Attenuation of Rayleigh-wave amplitudes across Eurasia

1977 ◽  
Vol 67 (3) ◽  
pp. 751-769
Author(s):  
Nazieh K. Yacoub ◽  
Brian J. Mitchell
Keyword(s):  
Rayleigh Wave ◽  
Regional Variation ◽  
Wave Amplitude ◽  
Period Range ◽  
Attenuation Coefficients ◽  
Nuclear Explosions ◽  
Amplitude Data ◽  
Standard Deviations ◽  
Data Yield ◽  
Rayleigh Mode

abstract Surface waves generated by six earthquakes and two nuclear explosions are used to study the attenuation coefficients of the fundamental Rayleigh mode across Eurasia. Rayleigh-wave amplitude data yield average attenuation coefficients at periods between 4 and 50 sec. The data exhibit relatively large standard deviations and in some cases the average attenuation coefficients take on negative values which may be due to regional variations of the attenuative properties of the crust, lateral refraction, multipathing and scattering. A method has been developed to investigate the regional variation in the attenuative properties of the Eurasian crust and its effect on surface-wave amplitude data, employing the evaluated average attenuation coefficients for the fundamental Rayleigh mode. For this investigation, Eurasia is divided into two regions, one considered to be relatively stable, and the other considered to be tectonic in nature. This regionalization shows that the tectonic regions exhibit higher attenuation than the stable regions in the period range below about 20 sec, whereas in the period range above about 20 sec, no clear difference can be observed for the two regions. Although the effects of lateral refraction and multipathing may still significantly affect the observations, the regionalization lowers the standard deviations considerably and eliminates the negative values which were obtained in the unregionalized determinations.

An algorithm for automated tsunami warning in French Polynesia based on mantle magnitudes

1989 ◽  
Vol 79 (4) ◽  
pp. 1177-1193
Author(s):  
Jacques Talandier ◽  
Emile A. Okal
Keyword(s):  
Rayleigh Wave ◽  
Seismic Moment ◽  
Rayleigh Waves ◽  
French Polynesia ◽  
Tsunami Warning ◽  
Period Range ◽  
Wave Duration ◽  
T Wave ◽  
The Moment ◽  
Historical References

Abstract We have developed a new magnitude scale, Mm, based on the measurement of mantle Rayleigh-wave energy in the 50 to 300 sec period range, and directly related to the seismic moment through Mm = log10M0 − 20. Measurements are taken on the first passage of Rayleigh waves, recorded on-scale on broadband instruments with adequate dynamical range. This allows estimation of the moment of an event within minutes of the arrival of the Rayleigh wave, and with a standard deviation of ±0.2 magnitude units. In turn, the knowledge of the seismic moment allows computation of an estimate of the high-seas amplitude of a range of expectable tsunami heights. The latter, combined with complementary data from T-wave duration and historical references, have been integrated into an automated procedure of tsunami warning by the Centre Polynésien de Prévention des Tsunamis (CPPT), in Papeete, Tahiti.

Worldwide investigation of the mantle Rayleigh-wave group velocities

1973 ◽  
Vol 63 (1) ◽  
pp. 271-281
Author(s):  
Harsh K. Gupta ◽  
Tetsuo Santô
Keyword(s):  
Rayleigh Wave ◽  
Velocity Dispersion ◽  
Group Velocity Dispersion ◽  
Great Circle ◽  
Wave Group ◽  
High Group ◽  
Period Range ◽  
Very High ◽  
Group Velocities ◽  
Existing Data

abstract An attempt to apply the crossing path technique to the division of the globe into similar regions of mantle Rayleigh-wave group-velocity dispersion characteristics failed because of the paucity of existing data (for about 80 great-circle paths). As a first step to achieve this goal, mantle Rayleigh-wave group velocities have been obtained for 31 new great-circle paths in the 80- to 240-sec period range. The data have been divided into four groups on the basis of dispersion behavior and compared with Dziewonski's (1971) results. An interesting finding has been the very high group velocities for the 6-MUN path, higher than any reported so far.

Crustal and upper mantle velocity structure of the Pannonian Region using Rayleigh wave ambient noise tomography

2021 ◽  
Author(s):  
Máté Timkó ◽  
Lars Wiesenberg ◽  
Amr El-Sharkawy ◽  
Zoltán Wéber ◽  
Thomas Meier ◽  
...  
Keyword(s):  
Rayleigh Wave ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Pannonian Basin ◽  
Vertical Component ◽  
High Heat ◽  
Moho Depth ◽  
Ambient Noise Tomography ◽  
Period Range ◽  
Waveform Data

<p>The Pannonian Basin is located in Central-Europe surrounded by the Alpine, Carpathian, and Dinarides mountain ranges. This is a back-arc basin characterized by shallow Moho depth, updoming mantle and high heat flow. In this study, we present the results of the Rayleigh wave based ambient noise tomography to investigate the velocity structure of the Carpathian-Pannonian region. </p><p>For the ambient noise measurements, we collected the continuous waveform data from more than 1280 seismological stations from the broader Central-Eastern European region. This dataset embraces all the permanent and the temporary (AlpArray, PASSEQ, CBP, SCP) stations from the 9-degree radius of the Pannonian Basin which were operating between the time period between 2005 and 2018. All the possible vertical component noise cross-correlation functions were calculated and all phase velocity curves were determined in the 5-80 s period range using an automated measuring algorithm. </p><p>The collected dispersion measurements were then used to create tomographic images that are characterized by similar velocity anomalies in amplitude, pattern and location that are consistent with the well-known tectonic and geologic structure of the research area and are comparable to previous tomographic models published in the literature.</p>

Statistical analysis and interpretation of surface-wave anelastic attenuation data for the stable interior of North America

1975 ◽  
Vol 65 (5) ◽  
pp. 1115-1128 ◽  
Author(s):  
Robert B. Herrmann ◽  
Brian J. Mitchell
Keyword(s):  
North America ◽  
Hudson Bay ◽  
Seismic Region ◽  
Period Range ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Confidence Levels ◽  
Anelastic Attenuation ◽  
Rapid Transition ◽  
Attenuation Values

Abstract As a byproduct of determining the source characteristics of some earthquakes and underground nuclear explosions, a body of fundamental-mode Rayleigh- and Love-wave anelastic attenuation values is available for propagation paths in the stable interior of North America in the 5- to 50-sec-period range. The anelastic attenuation values were obtained from four earthquakes occurring in the New Madrid seismic region, one earthquake in the northern Hudson Bay region, and three underground nuclear explosions in the western United States. In obtaining the anelastic attenuation data, a simple statistical test was applied to test the reliability of the observations. The anelastic attenuation coefficients are presented together with their 95 per cent confidence levels. A stochastic form of the Backus-Gilbert inverse formalism was applied to a subset of these data to yield a Qβ model for the stable interior of North America. The model is characterized by relatively low Qβ values for the upper crust and a rapid transition to much higher values for the lower crust.

scholarly journals Rayleigh wave propagation in transversely isotropic magneto-thermoelastic medium with three-phase-lag heat transfer and diffusion

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Iqbal Kaur ◽  
Parveen Lata
Keyword(s):  
Heat Transfer ◽  
Rayleigh Wave ◽  
Homogeneous Medium ◽  
Transversely Isotropic ◽  
Phase Lag ◽  
Attenuation Coefficients ◽  
Three Phase ◽  
Stress Components ◽  
And Diffusion ◽  
Penetration Depths

Abstract The present research deals with the propagation of Rayleigh wave in transversely isotropic magneto-thermoelastic homogeneous medium in the presence of mass diffusion and three-phase-lag heat transfer. The wave characteristics such as phase velocity, attenuation coefficients, specific loss, and penetration depths are computed numerically and depicted graphically. The normal stress, tangential stress components, temperature change, and mass concentration are computed and drawn graphically. The effects of three-phase-lag heat transfer, GN type-III, and LS theory of heat transfer are depicted on the various quantities. Some particular cases are also deduced from the present investigation.

Statistical Relationship between Ultrasound Echo Envelope and Envelope Peak

1988 ◽  
Vol 10 (4) ◽  
pp. 265-274
Author(s):  
Ping He
Keyword(s):  
Attenuation Coefficient ◽  
Time Domain ◽  
Statistical Relationship ◽  
Attenuation Coefficients ◽  
Amplitude Data ◽  
Independent Amplitude ◽  
The Time Domain

This study shows that the amplitude information of ultrasound echoes is carried mainly by the envelope peaks (EPs). It is first shown that the EPs in an A-line represent the maximum number of independent amplitude data. It is then demonstrated that the entire envelope could be approximately reconstructed from the EPs. Finally, using the echo data from a tissue-mimicking phantom, it is found that there are no significant differences among the attenuation coefficients estimated from the EPs, the original envelope samples, and the reconstructed envelope samples. The results of this study indicate that, in the time domain, the attenuation coefficient can be most efficiently estimated from the envelope peaks.

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