Lateral variation and frequency dependence of coda-<i>Q</i>in the southern part of Iberia

Cañas, J. A.; Pujades, L. G.; Badal, José; Payo, G.; Miguel, F. De; Vidal, F.; Alguacil, Gerardo; Ibáñez, Jesús M.; Morales, J.

doi:10.1111/j.1365-246x.1991.tb01156.x

Cited by 26 publications

(14 citation statements)

References 14 publications

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“…The single scattering model of AKI and CHOUET, (1975) was extended to non-coincident source and receiver by SATO (1977), thus enabling one to analyze the coda waves just after the S-wave arrival. The Q c , quality factor of coda wave, has been estimated extensively in different parts of the world (AKI and CHOUET, 1975;SATO, 1977;ROECKER et al, 1982;PULLI, 1984;WU, 1985;DEL PEZZO et al, 1987AKI, 1988, 1989;HAVSKOV et al, 1989;IBANEZ et al, 1990;PUJADES et al, 1991;CANAS et al, 1991;AKINCI et al, 1994;LATCHMAN et al, 1996;ZELT et al, 1999;UGALDE et al, 2002;TRIPATHI and UGALDE, 2004;GIAMPICCOLO et al, 2004;YUN et al, 2007) and the conclusion is that, in general, it is higher in stable regions and lower in tectonically active regions (SATO and FEHLER, 1998). The estimated Q c values well fit the frequency dependent power law relation (Q c af n ) at higher frequencies (f [ 1 or so).…”

Section: Introductionmentioning

confidence: 99%

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Variation of Seismic Coda Wave Attenuation in the Garhwal Region, Northwestern Himalaya

Tripathi

Singh

Sharma

2011

Pure Appl. Geophys.

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Seismic coda wave attenuation (Q À1 c ) characteristics in the Garhwal region, northwestern Himalaya is studied using 113 short-period, vertical component seismic observations from local events with hypocentral distance less than 250 km and magnitude range between 1.0 to 4.0. They are located mainly in the vicinity of the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT), which are well-defined tectonic discontinuities in the Himalayas. Coda wave attenuation (Q À1 c ) is estimated using the single isotropic scattering method at central frequencies 1.5, 3, 5, 7, 9, 12, 16, 20, 24 and 28 Hz using several starting lapse times and coda window lengths for the analysis. Results show that the (Q À1 c ) values are frequency dependent in the considered frequency range, and they fit the frequency power law (Q À1The Q 0 (Q c at 1 Hz) estimates vary from about 50 for a 10 s lapse time and 10 s window length, to about 350 for a 60 s lapse time and 60 s window length combination. The exponent of the frequency dependence law, n ranges from 1.2 to 0.7; however, it is greater than 0.8, in general, which correlates well with the values obtained in other seismically and tectonically active and highly heterogeneous regions. The attenuation in the Garhwal region is found to be lower than the Q c -1 values obtained for other seismically active regions of the world; however, it is comparable to other regions of India. The spatial variation of coda attenuation indicates that the level of heterogeneity decreases with increasing depth. The variation of coda attenuation has been estimated for different lapse time and window length combinations to observe the effect with depth and it indicates that the upper lithosphere is more active seismically as compared to the lower lithosphere and the heterogeneity decreases with increasing depth.

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Section: Introductionmentioning

confidence: 99%

“…PUJADES et al (1991) described that the estimated Q c by single scattering models is a measure of Q i , mainly. However, GAO et al (1983) suggested that the multiple scattering model gives an estimate of Q i and Q s , though single scattering is a good approximation for the generation of coda waves at short lapse times (lapse time \100 s).…”

Section: Introductionmentioning

confidence: 99%

Variation of Seismic Coda Wave Attenuation in the Garhwal Region, Northwestern Himalaya

Tripathi

Singh

Sharma

2011

Pure Appl. Geophys.

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“…(ALOJ and AAPN). For more information about seismic stations and acquisition system see Alguacil et al (1991). The epicentral distance to the two seismic stations is about 45 km; the two stations are located at the east of the source area.…”

Section: Antequera Region (Spain)mentioning

confidence: 99%

“…This method is based on the single-scattering model for coda wave generation, developed during the seventies (e.g., Aki and Chouet, 1975;Sato, 1977). Since then, a great number of studies on the attenuation of coda waves have been carried out applying the single-scattering model, for numerous regions in the world (e.g., Roecker et al, 1982;Pulli, 1984;Pujades et al, 1990;Canas et al, 1991). Although there are more general models (e.g., Gao et al, 1983;Wu and Aki, 1988;Frankel and Wennerberg, 1987;Zeng et al, 1991), their use and application is less extended, due, in part, to the complexity of the mathematical expressions or to the instability of the numerical solutions (Peng et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Estimates of Coda-Q Using a Non-Linear Regression.

Ibáñez

Pezzo

Martini³

et al. 1993

J,Phys,Earth

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A non-linear regression technique (Gauss-Newton method) is used to fit the single-scattering model of coda wave generation to experimental data. Comparisons between these results and those obtained applying the technique used in seismological practice (logarithmic linearization of the model equation and least-squares fit) are made. Data used are: a) a synthetic coda generated by white Gaussian noise modulated with an attenuation factor, exp(-kt), and a geometrical spreading factor; b) seismograms provided by two seismic series that occurred in the Abruzzo (Italy) and Antequera (Southern Spain) regions.The study from synthetic data shows that when the signal-to-noise ratio of the final part of the coda is greater or equal to 5, there are no significant differences in the values of Qc inferred by both techniques. When the signal-to-noise ratio is less than 5, we observed that the log-log technique produces a systematic overestimation of the values of Qc. Results obtained with real seismograms show that the log-log technique overestimates the Qc values when compared with the Gauss-Newton method, when the whole coda is used. When a long coda is used, the Qc dependence on frequency estimated using log-log is different in some cases from the one obtained with the Gauss-Newton technique. The Qc dependence on the lapse-time is less pronounced when the Gauss-Newton technique is used. This effect is more evident when different coda durations are obtained fixing the start-time of coda analysis, and increasing the end-time of the same coda. This pattern is also observed for the Abruzzo (Italy) and Antequera (Spain) series; when the log-log technique is used, a lapse-time dependence is observed, but, when the Gauss-Newton technique is used, this dependence is less significant.

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“…Several studies have been carried out in varied geological terrains world wide to investigate the seismic wave attenuation property of the medium, characterize the seismic activity and discriminate seismically active regions from stable ones (AKI and CHOUET, 1975;SATO, 1977;ROECKER et al, 1982;PULLI, 1984;WU, 1985;AKI, 1988, 1989;HAVSKOV et al, 1989;IBANEZ et al, 1990;PUJADES et al, 1991;CANAS et al, 1991;AKINCI et al, 1994;ZELT et al, 1999;BIESCAS et al, 2007). In India, attenuation characteristics of a few regions have been investigated using coda waves: These include, Central and Western Himalayas (GUPTA et al, 1995;NARESH et al, 2005 andMUKHOPADHYAY et al, 2006), Koyna region (GUPTA et al, 1998), Kachchh (GUPTA et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Coda Q Estimates in the Andaman Islands Using Local Earthquakes

Parvez

Sutar

Mridula

et al. 2008

Pure appl. geophys.

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Abstract-The attenuation property of Andaman Island has been investigated analyzing coda waves from 57 local earthquakes in the magnitude range of 2.0-4.9, using the single backscattering model. These earthquakes waveforms, recorded on five broadband seismographs sited over the island from north to south during Nov. , corresponding to lapse time window lengths of 40 and 80 s, respectively. The variation of Q c with frequency, lapse time and also with the location of seismograph reflects the marked structural and compositional inhomogeneity with depth along the Andaman Islands. These observations are well correlated with the seismicity pattern and distinct high angle subduction beneath the island.

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Lateral variation and frequency dependence of coda-Qin the southern part of Iberia

Cited by 26 publications

References 14 publications

Variation of Seismic Coda Wave Attenuation in the Garhwal Region, Northwestern Himalaya

Variation of Seismic Coda Wave Attenuation in the Garhwal Region, Northwestern Himalaya

Estimates of Coda-Q Using a Non-Linear Regression.

Coda Q Estimates in the Andaman Islands Using Local Earthquakes

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