Including anelasticity effects is essential to accurately characterize the seismic response of the different physical models. Anelasticity is strongly temperature dependent and it can be used to discriminate between the cold and the hot scenarios. In fact viscoelastic relaxation at high temperature leads to dispersion (frequency dependence of seismic wave speeds) and dissipation (attenuation). The development of experimental techniques to measure the viscoelastic behavior at high temperature and seismic frequencies is beginning to provide direct constraints on the shear attenuation phenomena (e.g., Faul and Jackson, 2005). Extrapolation with pressure, which is still an important issue for the Earth, is less relevant for small planetary bodies where the pressure does not increase dramatically with depth. In this sense, we expect a (strong) constant attenuation throughout the hot adiabatic mantle. In the case of a cold mantle, we expect enhanced attenuation at the top of the mantle, and possibly at the core-mantle boundary. For the time being, we test the anelasticity effects using a model derived by Cammarano et al., 2003.
Berkeley Seismological Laboratory
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