Open AccessConstraining the kinetics of mantle phase changes with seismic data
Author(s) -
Durand S.,
Chambat F.,
Matas J.,
Ricard Y.
Publication year - 2012
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2012.05417.x
Subject(s) - attenuation , anelastic attenuation factor , geology , mantle (geology) , seismic wave , geophysics , phase (matter) , relaxation (psychology) , physics , optics , psychology , social psychology , quantum mechanics
SUMMARY 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 Earth’s 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.