Separation of intrinsic and scattering attenuation in the crust of central and eastern Alborz region, Iran

Farrokhi, Mohsen; Hamzehloo, H.; Rahimi, Habib; Zadeh, Mostafa Allameh

doi:10.1016/j.pepi.2016.02.005

Cited by 18 publications

(7 citation statements)

References 41 publications

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“…; line 2-Erzincan, Turkey [5]; line 3-Yunnan Province, China [57]; line 4-Racha, Georgia [46]; line 5-the Javakheti plateau, Georgia [51]; line 6-Arunachal Himalaya [8]; line 7-Tbilisi region (this study); line 8-the Bam region, Iran [58]; line 9-Northwest Caucasus [21]; line 10-Central Asia [59]; line 11-the Andaman Sea [7]. ; line 2-Umbria-Marche, Italy [41]; line 3-Racha, Georgia [46]; line 4-Arunachal Himalaya [8]; line 5-Tbilisi region (this study); line 6-W. Greece [60]; line 7-Andaman Sea [7]; line 8-Bam region, Iran [58]; line 9-Delhi, India [61]; line 10-Alborz region, Iran [62].…”

Section: Discussionmentioning

confidence: 75%

“…Figure 10: Comparison of (a) Q i and (b) Q sc values for different regions modified from[46]: (a) line 1-Etna, Italy[56]; line 2-Umbria-Marche, Italy[41]; line 3-Racha, Georgia[46]; line 4-Arunachal Himalaya[8]; line 5-Tbilisi region (this study); line 6-W. Greece[60]; line 7-Andaman Sea[7]; line 8-Bam region, Iran[58]; line 9-Delhi, India[61]; line 10-Alborz region, Iran[62].…”

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confidence: 85%

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Attenuation of Coda and Body Waves for Tbilisi and Surrounding Area, Georgia

Shengelia,

Jorjiashvili,

Godoladze

et al. 2024

International Journal of Geophysics

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The attenuation of high-frequency seismic waves was investigated in the crust beneath Tbilisi and the surrounding territory by analysing 225 local earthquakes that occurred from 2008 to 2020 and were recorded by eight seismic stations. The quality factors of coda waves QC and direct P and S waves, QP and QS, were estimated using the single backscattering model and the extended coda normalization method, respectively. The separation of intrinsic quality factors Qi from scattering quality factor QSC was fulfilled by Wennerberg’s method. Observed results show that all evaluated attenuation parameters are frequency-dependent in the frequency range of 1-32 Hz and increase with increasing frequency. Coda QC values increase also with increasing lapse time window from 20 s to 50 s and vary from 91±5 at 1.5 Hz to 1779±108 at 24 Hz, respectively. P waves attenuate slightly faster than S waves, and the ratio of QS/QP is more than unity and varies in a range of 1.5-1.8. The intrinsic and scattering quality factors are expressed by the following power laws: Qi=77±4f0.930±0.046 and QSC=219±6f0.924±0.050. The results show that Qi is close to QC, but QSC is larger than Qi, which means that intrinsic attenuation has a dominant role compared with the scattering effect. Our results were compared with those obtained in two other seismically active regions of Georgia, as well as with regions of the world. In general, the observed quality factors and their frequency-dependent relationships follow a similar trend, characterizing seismically active regions with complex tectonics. The calculated attenuation parameters characterize the entire earth’s crust under Tbilisi and the surrounding area. The results obtained will be useful in future seismological studies since the Q parameters are estimated for the first time for the given region.

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Section: Discussionmentioning

confidence: 75%

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confidence: 85%

Attenuation of Coda and Body Waves for Tbilisi and Surrounding Area, Georgia

Shengelia,

Jorjiashvili,

Godoladze

et al. 2024

International Journal of Geophysics

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“…By using different methods, the separation of Q i and Q s from Q c has been estimated both in Italy and worldwide, in many tectonic contexts: the Adaman Sea [65]; the Alborz region (Iran) [66]; the Almeria Basin, Southwestern Iberian Peninsula (for f c > 3 Hz) [47];…”

Section: Discussionmentioning

confidence: 99%

3D-Kernel Based Imaging of an Improved Estimation of (Qc) in the Northern Apulia (Southern Italy)

et al. 2021

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We investigate crustal seismic attenuation by the coda quality parameter (Qc) in the Gargano area (Southern Italy), using a recently released dataset composed of 191 small earthquakes (1.0 ≤ ML ≤ 2.8) recorded by the local OTRIONS and the Italian INGV seismic networks, over three years of seismic monitoring. Following the single back-scattering theoretical assumption, Qc was computed using different frequencies (in the range of 2–16 Hz) and different lapse times (from 10 to 40 s). The trend of Qc vs. frequency is the same as that observed in the adjacent Umbria-Marche region. Qc at 1 Hz varies between 11 and 63, indicating that the area is characterized by active tectonics, despite the absence of high-magnitude earthquakes in recent decades. The 3D mapping procedure, based on sensitivity kernels, revealed that the Gargano Promontory is characterized by very low and homogeneous Qc at low frequencies, and by high and heterogeneous Qc at high frequencies. The lateral variations of Qc at 12 Hz follow the trend of the Moho in this region and are in good agreement with other geophysical observations.

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“…Results of and in tectonic contests worldwide suggest that the attenuation of coda waves is dominated by the intrinsic attenuation (Padhy et al, 2011;Farrokhi et al, 2016;Pujades et al, 1997;Akinci et al, 1995;Aki & Chouet, 1975;Bianco et al, 2005;Tuvè et al, 2006 among the others). The predominance of the anelasticity on coda waves increases by increasing frequency since the percentage ratio moves from 48% at 3Hz to 70% at 12Hz (Table 2).…”

Section: The Comparison Betweenmentioning

confidence: 99%

Qβ, Qc, Qi and Qs of the Gargano Promontory (Southern Italy)

Lucente

Ninivaggi

Lorenzo

et al. 2023

Preprint

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We have provided the first estimate of scattering and intrinsic attenuation for the Gargano Promontory (Southern Italy) analyzing 190 local earthquakes with ML ranging from 1.0 to 2.8. To separate the intrinsic \({Q}_{i}\) and scattering \({Q}_{s}\) quality factors with the Wennerberg approach (1993), we have measured the direct S waves and coda quality factors (\({Q}_{\beta }\), \({Q}_{c}\)) in the same volume of crust. \({Q}_{\beta }\) parameter is derived with the coda normalization method (Aki, 1980) and \({Q}_{c}\) factor is derived with the coda envelope decay method (Sato, 1977). We selected the coda envelope by performing an automatic picking procedure from \({T}_{start}=1.5{T}_{S}\) up to 30 s after origin time (lapse time \({T}_{L}\)). All the obtained quality factors clearly increase with frequency. The \({Q}_{c}\) values correspond to those recently obtained for the area. The estimated \({Q}_{i}\) are comparable to the \({Q}_{c}\) at all frequencies and range between 100 and 1000. The \({Q}_{s}\) parameter shows higher values than \({Q}_{i}\), except for 8 Hz, where the two estimates are closer. This implies a predominance of intrinsic attenuation over the scattering attenuation. Furthermore, the similarity between \({Q}_{i}\) and \({Q}_{c}\) allows us to interpret the high \({Q}_{c}\) anomaly previously found in the northern Gargano Promontory up to a depth of 24 km, as a volume of crust characterized by very low seismic dumping produced by conversion of seismic energy into heat. Moreover, most of the earthquake foci fall in high \({Q}_{i}\) areas, indicating lower level of anelastic dumping and a brittle behavior of rocks.

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Separation of intrinsic and scattering attenuation in the crust of central and eastern Alborz region, Iran

Cited by 18 publications

References 41 publications

Attenuation of Coda and Body Waves for Tbilisi and Surrounding Area, Georgia

Attenuation of Coda and Body Waves for Tbilisi and Surrounding Area, Georgia

3D-Kernel Based Imaging of an Improved Estimation of (Qc) in the Northern Apulia (Southern Italy)

Qβ, Qc, Qi and Qs of the Gargano Promontory (Southern Italy)

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