Variation of coda wave attenuation in the Alborz region and central Iran

Rahimi, Habib; Motaghi, Khalil; Mukhopadhyay, S.; Hamzehloo, H.

doi:10.1111/j.1365-246x.2010.04574.x

Cited by 19 publications

(39 citation statements)

References 62 publications

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“…To invert phase and group velocity dispersions, we used the average Q S structural models to avoid anelastic dispersion effect. The average values of Q S are taken from the literature as ∼25 and ∼55 for crust and upper mantle (Cong and Mitchell, 1998;Motazedian, 2006;Rahimi and Hamzehloo, 2008;Ma'hood et al, 2009;Rahimi et al, 2009Rahimi et al, , 2010.…”

Section: Constructing the Starting Modelmentioning

confidence: 99%

Shear-Wave Velocity Tomography of the Lithosphere-Asthenosphere System beneath the Iranian Plateau

Rahimi¹,

Hamzehloo²,

Vaccari³

et al. 2014

Bulletin of the Seismological Society of America

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We conducted a tomographic inversion of Rayleigh-wave dispersion to obtain 2D phase and group velocity tomographic images in the 10-100 s period range and shear-wave velocity structures for the Iranian plateau. For this purpose, the fundamental mode of Rayleigh waves, recorded along 1586 paths by 29 broadband stations, was identified by applying the frequency time analysis (FTAN) to each epicenter-station path which simultaneously satisfies the two-station method conditions. The fundamental modes identified by FTAN have been used to determine the path-average interstation phase and group velocities at selected periods. With this procedure, 243 group and phase velocity dispersion curves were processed to obtain tomographic maps by applying the Yanovskaya-Ditmar formulation for periods in the 10-100 s range. Averaged dispersion curves of phase and group velocities, which represent six rather homogeneous regions, are computed. Finally, we used a fully nonlinear inversion procedure to derive tomographic images of the elastic structure of the lithosphere and asthenosphere of the six main structural and seismotectonic features of the Iranian plateau. The dense path coverage in the Iranian plateau permits us to produce images that have substantially higher lateral resolution compared to images currently available from global and regional group velocity studies. Tomographic maps at high frequencies are well correlated with the upper crust structure, especially with sediment layers thickness. Estimated shear-wave velocity structures are well correlated with the shield-like lithosphere structure in Zagros. A low-velocity zone (LVZ) is not detected in Alborz or the south Caspian basin, which can imply thrusting of the oceanic crust of the southern Caspian Sea under the Alborz to the south. LVZs are derived for the region east of Iran, central Iran, and Kopeh Dagh.

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Section: Constructing the Starting Modelmentioning

confidence: 99%

Shear-Wave Velocity Tomography of the Lithosphere-Asthenosphere System beneath the Iranian Plateau

Rahimi¹,

Hamzehloo²,

Vaccari³

et al. 2014

Bulletin of the Seismological Society of America

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“…Attenuation of the Alborz region has been studied by several investigators using different dataset and methods (e.g., Motazedian, 2006;Rahimi et al, 2010;Motaghi and Ghods, 2012;Naghavi et al, 2012). In this study, we estimated attenuation of the coda wave by using the SBS (Aki and Chouet, 1975) and single isotropic-scattering (SIS) models (Sato, 1977).…”

Section: Introductionmentioning

confidence: 99%

Estimation of Coda‐Wave Attenuation in the Central and Eastern Alborz, Iran

Farrokhi¹,

Hamzehloo²,

Rahimi³

et al. 2015

Bulletin of the Seismological Society of America

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The quality factor of coda (Q c ) waves has been estimated by using single backscattering and single isotropic scattering models. The earthquakes used were recorded by three permanent and one temporary network located in the central and eastern Alborz, Iran. The database was composed of 746 local earthquakes with local magnitude from 1.1 to 5.7. The estimated Q c has been found to be similar for lapse times greater than twice the S-wave travel time (2t S ) for both methods.The estimated Q c for central frequencies < 1:0 Hz shows less frequency dependency compared with the higher frequencies. By using a Q 0 f n relation, the average frequency dependence of Q c for the whole area has been estimated as 59f 1:03 , 69f 0:97 , 78f 0:97 , 105f 0:93 , 123f 0:89 , 159f 0:79 , and 203f 0:68 for central lapse times 30, 40, 50, 65, 85, 110, and 155 s, respectively. We found the value of Q 0 decreases at an average depth of 78 km, which may be the result of high dissipating media at this depth. The average Q c values, estimated for central and eastern Alborz and their frequencydependent relationships are similar to those of tectonically active regions.

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“…Jin and Aki, 1986;Havskov et al, 1989;Ibañez et al, 1990;Singh and Hermann, 1983;Hellweg et al, 1995;Mukhopadhyay and Tyagi, 2007;Mukhopadhyay et al, 2008;Rahimi et al, 2010;Singh et al, 2011a) have shown that Q 0 is normally high in stable regions and low in active tectonic regions while its frequency dependence parameter n has an inverse behavior. In Fig.…”

Section: Comparison Of Q C With Global Observationsmentioning

confidence: 91%