S-wave attenuation characteristics in the Galeras volcanic complex (south western Colombia)

Ugalde, Arantza; Carcolé, E.; Vargas, Carlos

doi:10.1016/j.pepi.2010.04.009

Cited by 14 publications

(4 citation statements)

References 30 publications

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“…Paasschens (1997) introduced an approximation for RTE (Boltzmann equation) for 1, 2, 3, and 4 dimensions and heuristically proposed a better approximation of RTE, based on the interpolation of exact solution of RTE for 2 and 4 dimensions. The new approximation has been used in attenuation determination of S waves (Ugalde et al, 2010), separation of intrinsic and scattering attenuation (Abubakirov, 2005), and seismic moment determination (Sens-Schönfelder and Wegler, 2006). We used Paasschens (1997) approximation to test the reliability of our processing for both SBS and SIS methods.…”

Section: Attenuation Variation With Depthmentioning

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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Section: Attenuation Variation With Depthmentioning

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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“…Colored circles indicate similar tectonic units in Taiwan: crystalline massifs (HR and CR) are in blue, sedimentary and highly tectonized areas (Western Foothills, Coastal Plain, and Ilan Plain) are in green, and stations in Coastal Range and Longitudinal Valley (volcanic materials) are in yellow. Old orogens (mainly western Europe) are marked by blue diamonds (Lacombe et al., 2003; Sens‐Schönfelder & Wegler, 2006; Sens‐Schönfelder et al., 2009) and volcanoes by red diamonds (Del Pezzo et al., 2001; Mayeda et al., 1992; Ugalde et al., 2010; Wegler, 2003). Minimum and maximum values for absorption and scattering in Japan (Carcolé & Sato, 2010), Korea (Rachman et al., 2015) and North America (Eulenfeld & Wegler, 2017) are also shown.…”

Section: Discussionmentioning

confidence: 99%

“…It is also noteworthy in Figure 11 that the spatial variations of attenuation in Taiwan are much larger than in Japan which covers a larger area -compared to Taiwan-but with a comparable diversity of geological structures. (Lacombe et al, 2003;Sens-Schönfelder & Wegler, 2006;Sens-Schönfelder et al, 2009) and volcanoes by red diamonds (Del Pezzo et al, 2001;Mayeda et al, 1992;Ugalde et al, 2010;Wegler, 2003). Minimum and maximum values for absorption and scattering in Japan (Carcolé & Sato, 2010), Korea (Rachman et al, 2015) and North America (Eulenfeld & Wegler, 2017) are also shown.…”

Section: Comparison With Others Studiesmentioning

confidence: 94%

Anomalous Attenuation of High‐Frequency Seismic Waves in Taiwan: Observation, Model and Interpretation

2023

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High resolution maps of seismic attenuation parameters in Taiwan have been obtained from a modified “Multiple Lapse Time Window Analysis” (MLTWA). At most of the stations in porous sedimentary and highly faulted areas in Taiwan, the conventional modeling of MLTWA based on the scalar theory of radiative transfer in a half‐space with isotropic scattering fails to explain the spatio‐temporal distribution of the whole S‐wave train. Using Monte Carlo simulations of wave transport, we demonstrate that this anomalous energy distribution in the coda may be modeled by multiple anisotropic scattering of seismic waves. In addition to the scattering quality factor Qsc ${Q}_{sc}$, we introduce a parameter g $g$ (independent of Qsc ${Q}_{sc}$) which determines the angular redistribution of energy upon scattering (scattering anisotropy). We inverted the attenuation parameters Qsc−1 ${Q}_{sc}^{-1}$, Qi−1 ${Q}_{i}^{-1}$ and g in three frequency bands (1–2, 2–4, and 4–8 Hz). Overall, Taiwan is more attenuating than most orogens with a mean effective scattering loss Qsc∗−1=Qsc−1(1−g) ${\left({Q}_{sc}^{\ast }\right)}^{-1}={Q}_{sc}^{-1}(1-g)$ and a mean intrinsic absorption Qi−1 ${Q}_{i}^{-1}$ of 2.5 × 10−3 and 9 × 10−3 at 1.5 Hz, respectively. Scattering loss Qsc∗−1 ${\left({Q}_{sc}^{\ast }\right)}^{-1}$ varies over more than one order of magnitude across Taiwan while absorption variations reach approximately 30%. The more attenuating zones are the Coastal Range and the Coastal Plain where scattering dominates over absorption at low frequency, and inversely at high frequency. These regions are also characterized by strong backscattering (g $g$ < −0.85) at 1.5 Hz and rather high VP/VS ${V}_{P}/{V}_{S}$ ratio. We propose that the observed strong back‐scattering at low frequency, related to large impedance fluctuations in the crust, is induced by the presence of fluids.

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“…absorption) dominates over absorption. (mainly western Europe) are marked by blue diamonds (Lacombe et al, 2003;Sens-Schönfelder & Wegler, 2006;Sens-Schönfelder et al, 2009) and volcanoes by red diamonds (Mayeda et al, 1992;Del Pezzo et al, 2001;Wegler, 2003;Ugalde et al, 2010). Minimum and maximum values for absorption and scattering in Japan (Carcolé & Sato, 2010), Korea (Rachman et al, 2015) and North America (Eulenfeld & Wegler, 2017) are also shown.…”

Section: Comparison With Others Studiesmentioning

confidence: 99%

Anomalous attenuation of high-frequency seismic waves in Taiwan: observation, model and interpretation

Calvet

Margerin

Hung

2022

Preprint

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High resolution maps of seismic attenuation parameters in Taiwan have been obtained by using a modified "Multiple Lapse Time Window Analysis' (MLTWA). At most of the stations in porous sedimentary and highly faulted areas in Taiwan, the conventional modeling of MLTWA based on the scalar theory of radiative transfer in a half-space with isotropic scattering fails to explain the spatio-temporal distribution of the whole S wavetrain. Using Monte Carlo simulations of wave transport, we demonstrate that this anomalous energy distribution in the coda may be modelled by multiple anisotropic scattering of seismic waves. In addition to the scattering quality factor Qsc, we introduce a parameter g (independant of Qsc) which determines the angular redistribution of energy upon scattering (scattering anisotropy). We determine the attenuation parameters Qsc -1 , Q i -1 and g in three frequency bands (1-2, 2-4 and 4-8Hz). Overall, Taiwan is more attenuating than most orogens with a mean effective scattering loss (Qsc * ) -1 =Qsc -1 (1-g) about 0.025 and a mean intrinsic absorption Q i -1 about 0.009 at 1.5Hz.Scattering loss (Qsc * ) -1 varies over more than one order of magnitude across Taiwan while absorption fluctuations are about 30%. The more attenuating zones are the Coastal Range and the Coastal Plain where scattering dominates over absorption at low frequency, and inversely at high frequency. These regions are also characterized by strong backscattering (g<-0.85) at 1.5Hz and rather high V P /V S ratio. We speculate that the observed strong back-scattering at low frequency is related to strong impedance fluctuations in the crust induced by the presence of fluids.

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S-wave attenuation characteristics in the Galeras volcanic complex (south western Colombia)

Cited by 14 publications

References 30 publications

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

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

Anomalous Attenuation of High‐Frequency Seismic Waves in Taiwan: Observation, Model and Interpretation

Anomalous attenuation of high-frequency seismic waves in Taiwan: observation, model and interpretation

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