The trouble with seeing double
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چکیده
[1] The recently discovered phase transition for (Mg,Fe)SiO3 from perovskite to post-perovskite structure for pressure-temperature conditions in the lowermost mantle provides a plausible mechanism to explain a several percent shear velocity increase detected at the top of the D00 region in many regions. The phase transition has a large positive Clapeyron slope, and given the likely presence of a strong temperature increase just above the core-mantle boundary, D00 conditions may reintersect the phase boundary, resulting in a thin layer of perovskite below a lens of post-perovskite, separated by a few percent velocity decrease. Detection of such a velocity decrease is shown to be much harder than detection of the shallower velocity increase due to fundamental properties of seismic waves; purported observations in support of a doublediscontinuity are re-evaluated based on waveform modeling. Waveform stacking procedures are required for reliable detection of the lower half of any double-crossing of the phase boundary. Citation: Flores, C., and T. Lay (2005), The trouble with seeing double, Geophys. Res. Lett., 32, L24305, doi:10.1029/2005GL024366.
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تاریخ انتشار 2005