Seismic velocity
Methods
Seismic velocity can specified in a number of ways
GeoParams.MaterialParameters.SeismicVelocity.ConstantSeismicVelocity — TypeConstantSeismicVelocity(Vp=8.1 km/s, Vs=4.5km/s)Set a constant seismic P and S-wave velocity:
\[ V_p = cst\]
\[ V_s = cst\]
where $V_p, V_s$ are the P-wave and S-wave velocities [$km/s$].
In addition, you can use phase diagram lookup tables to compute seismic velocities as a function of pressure and temperature.
Seismic velocity correction for partial melt
Methods
The routine uses the reduction formulation of Clark et al., (2017) and is based on the equilibrium geometry model for the solid skeleton of Takei et al., 1998.
Seismic S-wave velocity correction for (shallow depth) porosity
Methods
This routine is based on the equilibrium geometry model for the solid skeleton of Takei et al. (1998) and the porosity-depth empirical relationship of Chen et al. (2020)
Seismic velocity correction for anelasticity
Methods
The routine uses the reduction formulation of karato (1993), using the quality factor formulation from Behn et al. (2009)
Computational routines
To compute a correction of S-wave velocity for anelasticity, use this:
GeoParams.MaterialParameters.SeismicVelocity.anelastic_correction — Function Vs_anel = anelastic_correction(water::Int64, Vs0::Float64,P::Float64,T::Float64)This routine computes a correction of S-wave velocity for anelasticity
Input:
water: water flag, 0 = dry; 1 = dampened; 2 = water saturatedVs0: S-wave velocitiy of the solid phase (with or without melt correction)P: pressure given in PaT: temperature given in °K
Output:
Vs_anel: corrected S-wave velocity for anelasticity
The routine uses the reduction formulation of Karato (1993), using the quality factor formulation from Behn et al. (2009)
References:
Karato, S. I. (1993). Importance of anelasticity in the interpretation of seismic tomography. Geophysical research letters, 20(15), 1623-1626.
Behn, M. D., Hirth, G., & Elsenbeck II, J. R. (2009). Implications of grain size evolution on the seismic structure of the oceanic upper mantle. Earth and Planetary Science Letters, 282(1-4), 178-189.