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

A. Dobrynina (1) , J. Albaric (2, 3) , Anne Deschamps (4) , Julie Perrot (2) , R.W. Ferdinand (5) , Jacques Déverchère (2) , V.A. San’kov (6, 1) , V.V. Chechel’nitskii (1)

1 IEC - Institute of the Earth's Crust
2 LDO - Domaines Océaniques
3 LCE - Laboratoire Chrono-environnement (UMR 6249)
4 GEOAZUR 7329 - Géoazur
5 University of Dar-es-Salaam - Department of Geology
6 Irkutsk State University

The seismic effective quality factor (QC) and its frequently dependences or the frequency parameter (n) and attenuation coefficient (δ) for the Earth’s crust and upper mantle of the North Tanzanian divergence zone (East African rift system) were estimated from an analysis of the earthquake coda waves recorded in the SEISMO-TANZ’07 French-Tanzanian seismic experiment. The QC values increase and the n and δ values decrease with increasing frequency and length of the lapse time window. This behavior of the attenuation parameters may be evidence that the degree of heterogeneity of the lithosphere decreases with depth. Comparison of the depth variations in the attenuation coefficient δ and the frequency parameter n with the velocity structure of the region shows that there is a distinct change in the behavior of seismic wave attenuation at velocity discontinuities. The obtained attenuation parameters were compared with the same parameters obtained in our previous studies for other continental rift systems—the Baikal rift system (Eurasia) and the Basin and Range Province (North America).

Mots clés: seismic quality factor; attenuation; coda; North Tanzanian divergence; East African rift system

Domaines: Géophysique [physics.geo-ph]

A. Dobrynina, J. Albaric, Anne Deschamps, Julie Perrot, R.W. Ferdinand, et al.. Seismic wave attenuation in the lithosphere of the North Tanzanian divergence zone (East African rift system). Russian Geology and Geophysics, 2017, 58 (2), pp.253 - 265. ⟨10.1016/j.rgg.2016.03.016⟩. ⟨hal-01468001⟩