Seismic wave attenuation in the lithosphere of the North Tanzanian divergence zone (<i>East African rift system</i>)

Добрынина, А. А.; Albaric, Julie; Deschamps, A.; Perrot, Julie; Ferdinand, R.; Déverchère, Jacques; Sankov, V. A.; Чечельницкий, В. В.

doi:10.1016/j.rgg.2016.03.016

Cited by 5 publications

(4 citation statements)

References 25 publications

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“…Low values of Q o (<200) characterize the region with high tectonic activity; otherwise, high values of Q o (>600) describe stable seismic activity [Aki and Chouet, 1975;Mak et al, 2004;Sertçelik, 2012]. At the same time, if n is higher than 0.8, the crust and upper mantle are tectonically active; while n values lower than 0.5, characterize an inactive region [Atkinson, 2004;Dasovic et al, 2012;Ranasinghe et al, 2014;Dobrynina et al, 2017;Banerjee and Kumar, 2017].…”

Section: Methodsmentioning

confidence: 99%

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Yavuz

Barış²

2019

Annals of Geophysics

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The Armutlu Peninsula, is located in a geologically complex system on the North Anatolian Fault Zone and inside the high populated Marmara Region. Due to its location and importance, the Marmara Region has been subject to various studies in the past; now, this study is aimed to determine the local attenuation characteristic of the Armutlu Peninsula. In this study, 75 earthquake data that were recorded between 2013-2014, were analyzed by 9 seismic stations. The magnitudes (Ml) and the focal depths of the earthquakes vary from 1.5 to 3.3 and 0.9 to 16.9 km, respectively. A single back-scattering model was used for calculation of the coda wave quality factor. The lapse times were determined between 20 and 40 s at intervals of 5 s and they were filtered at central frequencies of 1.5, 3, 6, 9 and 12 Hz band-pass designed filter. Minimum 5 signal/noise ratio and 0.7 correlation coefficient data used to obtain reliable results. The CODAQ subroutine integrated in the SEISAN software was used for data processing. For each station, low values of the quality factor at 1 Hz (Q o ) and high values of the frequency dependent parameter (n) were determined. In the Armutlu Peninsula and its surroundings, Q c =51f 0.91 for 20 s and Q c =112f 0.72 for 40 s window lengths were calculated by using 9 stations. There is a tendency between increasing Q o and decreasing n parameters. Otherwise, for station TRML, located near the geothermal hotspot, these parameters are in direct proportion with each other, as Q c =46f 0.97 for 20 s and Q c =74f 1.06 for 40 s window lengths. These parameter changes are directly connected with the geothermal activity. the rate of coda wave attenuation [Aki, 1969]. Local/regional recorded coda waves (up to 100 km epicentral distance) and their power spectra as well as coda duration are relatively independent from the focal distance [Aki and Chouet, 1975]. Q c determination studies are generally performed in tectonically active fields, active volcanic regions, earthquake swarm areas, magmatic flows and geothermal areas [

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Section: Methodsmentioning

confidence: 99%

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Yavuz

Barış²

2019

Annals of Geophysics

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“…Расчет сей-смической добротности по коде (Q C ) для выбран-ных районов выполнялся авторами ранее [Dobrynina, 2013;Dobrynina et al, 2016aDobrynina et al, , 2016bDobrynina et al, , 2017 с использованием модели однократного рассеяния [Aki, Chouet, 1975]. Оценка затухания S-волн выпол-нялась по максимальным амплитудам прямых волн.…”

Section: методы и данныеunclassified

“…Общее количество использованных сейсмических трасс для Байкальской рифтовой системы состав-ляет 1715 [Dobrynina et al, 2016b], для Северо-Танзанийской дивергентной зоны -1008 [Dobrynina et al, 2017] и для Провинции Бассейнов и Хреб-тов -289 [Dobrynina, 2013]. На базе полученных ве-личин Q С для всех значений длины окна W были определены эмпирические зависимости добротно-сти от частоты (табл.…”

Section: результатыunclassified

“…9). Сопоставление глубинных вариаций затухания и скоростного строения иссле-дуемых регионов показало, что изменения коэф-фициента затухания и частотного параметра при-урочены к скоростным границам в среде [Dobrynina, 2013;Dobrynina et al, 2016aDobrynina et al, , 2016bDobrynina et al, , 2017.…”

Section: обсуждение результатовunclassified

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Factors influencing seismic wave attenuation in the lithosphere in continental rift zones

Добрынина¹,

Sankov²,

Девершер

et al. 2017

Geodin. tektonofiz.

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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.Key words: 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 GEODYNAMICS & TECTONOPHYSICS P U B L I S H E D B Y T H E I N S T I T U T E O F T H E E A R T H ' S C R U S T S I B E R I A N B R A N C H O F R U S S I A N A C A D E M Y O F S C I E N C E

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Coda wave seismic structure beneath the Indian Ocean region and its implications to seismotectonics and structural heterogeneity

Ekka

Vandana

Roy

et al. 2020

Journal of Asian Earth Sciences

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Seismic wave attenuation in the lithosphere of the North Tanzanian divergence zone (East African rift system)

Cited by 5 publications

References 25 publications

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Factors influencing seismic wave attenuation in the lithosphere in continental rift zones

Coda wave seismic structure beneath the Indian Ocean region and its implications to seismotectonics and structural heterogeneity

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