Factors influencing seismic wave attenuation in the lithosphere in continental rift zones
Attenuation of seismic waves in the crust and the upper mantle has been studied in three global rift systems: the Baikal rift system (Eurasia), the North Tanzanian divergence zone (Africa) and the Basin and Range Province (North America). Using the records of direct and coda waves of regional earthq...
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Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust
2017-03-01
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| Series: | Геодинамика и тектонофизика |
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| Online Access: | https://www.gt-crust.ru/jour/article/view/335 |
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| author | А. А. Dobrynina V. A. Sankov J. Déverchère V. V. Chechelnitsky |
| author_facet | А. А. Dobrynina V. A. Sankov J. Déverchère V. V. Chechelnitsky |
| author_sort | А. А. Dobrynina |
| collection | DOAJ |
| description | Attenuation of seismic waves in the crust and the upper mantle has been studied in three global rift systems: the Baikal rift system (Eurasia), the North Tanzanian divergence zone (Africa) and the Basin and Range Province (North America). Using the records of direct and coda waves of regional earthquakes, the single scattering theory [Aki, Chouet, 1975], the hybrid model from [Zeng, 1991] and the approach described in [Wennerberg, 1993], we estimated the seismic quality factor (QC), frequency parameter (n), attenuation coefficient (δ), and total attenuation (QT). In addition, we evaluated the contributions of two components into total attenuation: intrinsic attenuation (Qi), and scattering attenuation (Qsc). Values of QC are strongly dependent on the frequency within the range of 0.2–16 Hz, as well as on the length of the coda processing window. The observed increase of QC with larger lengths of the coda processing window can be interpreted as a decrease in attenuation with increasing depth. Having compared the depth variations in the attenuation coefficient (δ) and the frequency (n) with the velocity structures of the studied regions, we conclude that seismic wave attenuation changes at the velocity boundaries in the medium. Moreover, the comparison results show that the estimated variations in the attenuation parameters with increasing depth are considerably dependent on utilized velocity models of the medium. Lateral variations in attenuation of seismic waves correlate with the geological and geophysical characteristics of the regions, and attenuation is primarily dependent on the regional seismic activity and regional heat flow. The geological inhomogeneities of the medium and the age of crust consolidation are secondary factors. Our estimations of intrinsic attenuation (Qi) and scattering attenuation (Qsc) show that in all the three studied regions, intrinsic attenuation is the major contributor to total attenuation. Our study shows that the characteristics of seismic wave attenuation in the three different rift systems are consistent with each other, and this may suggest that the lithosphere in the zones of these different rift systems has been modified to similar levels. |
| format | Article |
| id | doaj-art-d7d54e22b2bb486da608b2fb90ef63e1 |
| institution | Kabale University |
| issn | 2078-502X |
| language | English |
| publishDate | 2017-03-01 |
| publisher | Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust |
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| series | Геодинамика и тектонофизика |
| spelling | doaj-art-d7d54e22b2bb486da608b2fb90ef63e12025-08-20T03:44:19ZengRussian Academy of Sciences, Siberian Branch, Institute of the Earth's crustГеодинамика и тектонофизика2078-502X2017-03-018110713310.5800/GT-2017-8-1-0234229Factors influencing seismic wave attenuation in the lithosphere in continental rift zonesА. А. Dobrynina0V. A. Sankov1J. Déverchère2V. V. Chechelnitsky3Institute of the Earth's Crust, Siberian Branch of RAS Geological Institute, Siberian Branch of RASInstitute of the Earth's Crust, Siberian Branch of RAS Irkutsk State University Irkutsk Scientific Center, Siberian Branch of RASInstitut Universitaire Européen de la Mer, Université de Bretagne OccidentaleBaikal Branch of Federal Research Center Geophysical Survey of RASAttenuation of seismic waves in the crust and the upper mantle has been studied in three global rift systems: the Baikal rift system (Eurasia), the North Tanzanian divergence zone (Africa) and the Basin and Range Province (North America). Using the records of direct and coda waves of regional earthquakes, the single scattering theory [Aki, Chouet, 1975], the hybrid model from [Zeng, 1991] and the approach described in [Wennerberg, 1993], we estimated the seismic quality factor (QC), frequency parameter (n), attenuation coefficient (δ), and total attenuation (QT). In addition, we evaluated the contributions of two components into total attenuation: intrinsic attenuation (Qi), and scattering attenuation (Qsc). Values of QC are strongly dependent on the frequency within the range of 0.2–16 Hz, as well as on the length of the coda processing window. The observed increase of QC with larger lengths of the coda processing window can be interpreted as a decrease in attenuation with increasing depth. Having compared the depth variations in the attenuation coefficient (δ) and the frequency (n) with the velocity structures of the studied regions, we conclude that seismic wave attenuation changes at the velocity boundaries in the medium. Moreover, the comparison results show that the estimated variations in the attenuation parameters with increasing depth are considerably dependent on utilized velocity models of the medium. Lateral variations in attenuation of seismic waves correlate with the geological and geophysical characteristics of the regions, and attenuation is primarily dependent on the regional seismic activity and regional heat flow. The geological inhomogeneities of the medium and the age of crust consolidation are secondary factors. Our estimations of intrinsic attenuation (Qi) and scattering attenuation (Qsc) show that in all the three studied regions, intrinsic attenuation is the major contributor to total attenuation. Our study shows that the characteristics of seismic wave attenuation in the three different rift systems are consistent with each other, and this may suggest that the lithosphere in the zones of these different rift systems has been modified to similar levels.https://www.gt-crust.ru/jour/article/view/335baikal rift systemeast african rift systemnorth american basin and range provinceattenuation of seismic wavesseismic quality factorseismicitycoda wavesintrinsic attenuationscattering attenuationheat flow |
| spellingShingle | А. А. Dobrynina V. A. Sankov J. Déverchère V. V. Chechelnitsky Factors influencing seismic wave attenuation in the lithosphere in continental rift zones Геодинамика и тектонофизика baikal rift system east african rift system north american basin and range province attenuation of seismic waves seismic quality factor seismicity coda waves intrinsic attenuation scattering attenuation heat flow |
| title | Factors influencing seismic wave attenuation in the lithosphere in continental rift zones |
| title_full | Factors influencing seismic wave attenuation in the lithosphere in continental rift zones |
| title_fullStr | Factors influencing seismic wave attenuation in the lithosphere in continental rift zones |
| title_full_unstemmed | Factors influencing seismic wave attenuation in the lithosphere in continental rift zones |
| title_short | Factors influencing seismic wave attenuation in the lithosphere in continental rift zones |
| title_sort | factors influencing seismic wave attenuation in the lithosphere in continental rift zones |
| topic | baikal rift system east african rift system north american basin and range province attenuation of seismic waves seismic quality factor seismicity coda waves intrinsic attenuation scattering attenuation heat flow |
| url | https://www.gt-crust.ru/jour/article/view/335 |
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