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Qc, Qb, Qi and Qs attenuation parameters in the Umbria–Marche (Italy) region
Language
English
Obiettivo Specifico
3.1. Fisica dei terremoti
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/218 (2013)
ISSN
0031-9201
Electronic ISSN
1872-7395
Publisher
Elsevier Science Limited
Pages (printed)
19 - 30
Issued date
2013
Abstract
The attenuation of coda and S waves has been inferred for the Umbria–Marche region (central Italy) using
seismic waveforms collected during the 1997 seismic crisis. The selected dataset is composed of 343
small magnitude (1.4 < ML < 4.2) earthquakes recorded at a temporary array composed of 23 seismic stations.
The Sato (1977) method, based on the assumption of single isotropic scattering has been used to
infer Qc, considering three different lapse times (20, 30 and 40 s). The coda normalization method (Aki,
1980) has been used to infer Qb. Both Qc and Qb show a clear frequency dependence with a different frequency
dependent parameter. The frequency dependence of Qc is comparable with that previously found
in the same area and around it. Using the method of Wennerberg (1993), intrinsic and scattering attenuation
have been separated. Intrinsic attenuation is found to be close to coda attenuation and dominates
over scattering dissipation. Coda Q increases with increasing lapse time but at a rate smaller than that
observed in other areas of the Earth. Coda and intrinsic attenuation in the Umbria–Marche region are very
high compared to other seismic active regions of the Earth. The retrieved high values of intrinsic attenuation
may be explained in terms of the previously hypothesized fluid-pressurized regime of the crust in
the central Apennines (Miller et al., 2004).
seismic waveforms collected during the 1997 seismic crisis. The selected dataset is composed of 343
small magnitude (1.4 < ML < 4.2) earthquakes recorded at a temporary array composed of 23 seismic stations.
The Sato (1977) method, based on the assumption of single isotropic scattering has been used to
infer Qc, considering three different lapse times (20, 30 and 40 s). The coda normalization method (Aki,
1980) has been used to infer Qb. Both Qc and Qb show a clear frequency dependence with a different frequency
dependent parameter. The frequency dependence of Qc is comparable with that previously found
in the same area and around it. Using the method of Wennerberg (1993), intrinsic and scattering attenuation
have been separated. Intrinsic attenuation is found to be close to coda attenuation and dominates
over scattering dissipation. Coda Q increases with increasing lapse time but at a rate smaller than that
observed in other areas of the Earth. Coda and intrinsic attenuation in the Umbria–Marche region are very
high compared to other seismic active regions of the Earth. The retrieved high values of intrinsic attenuation
may be explained in terms of the previously hypothesized fluid-pressurized regime of the crust in
the central Apennines (Miller et al., 2004).
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article
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