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Geophysical Journal International 189, 3 (2012) 1557-1564
Constraining the kinetics of mantle phase changes with seismic data
Stéphanie Durand ( ) 1, Frédéric Chambat 1, Jan Matas 1, Yanick Ricard 1

In a system where two phases coexist, a seismic wave can disrupt the pre-existing equilibrium and induce a re-equilibration process. Because the kinetics of the phase change is not instantaneous, the transformation induces an attenuation of the wave that can be quantified using an appropriate physical theory. Kinetics of Earths phase transitions are not well known: in this paper we show that they can be constrained by seismic attenuation data. We quantify the influence of a phase transition upon seismic mode attenuation and body wave reflexion coefficient. We perform a numerical application for the olivine to wadsleyite transition at 410 km depth, assuming a phase loop thickness of 10 km. We show that the relaxation time that controls the frequency band of attenuation and the velocity at which the interface evolves when submitted to a pressure disequilibrium, is likely larger than 7000 s. For this kinetics slower than typical seismic waves periods, the transformation loop does not affect S waves attenuation but potentially that of P waves and normal modes
1 :  Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE)
CNRS : UMR5276 – INSU – Université Claude Bernard - Lyon I (UCBL) – École Normale Supérieure (ENS) - Lyon
Planète et Univers/Sciences de la Terre/Géochimie

Planète et Univers/Sciences de la Terre/Géophysique


Sciences de l'environnement/Milieux et Changements globaux
Elasticity and anelasticity – Phase transitions – Body waves – Surface waves and free oscillations – Seismic attenuation – Wave propagation