Constraining velocity and density contrasts across the crustmantle boundary with receiver function amplitudes
Abstract
This paper investigates the ability of Pwave receiver functions to constrain both the velocity and density contrasts across the Moho. Expressions for receiver function amplitudes corresponding to a layer over a halfspace are extended to media with depthdependent properties by explicitly accounting for freesurface reflection coefficients. Forward numerical computations show that receiver function amplitudes become frequencydependent for depthdependent structures and that, for a given frequency, wavelengths associated to Ps converted phases are larger than wavelengths associated to multiply reverberated phases. When consistent measurements of the amplitudes of Ps phase and multiples can be obtained, the extended expressions suffice to account for the observed amplitudes. Receiver function amplitudes are sensitive to both velocity and density contrasts across the Moho, and a twostep gridsearch procedure is proposed to recover the contrasts from their measurement. The nearsurface velocity is recovered in the first step from the amplitude of the direct P wave and then used in the second step to work out the relative density and Swave velocity contrast from the amplitude of the secondary phases. Examples from central Spain (PAB) and the Indian Shield (HYB) are discussed and demonstrate that receiver function amplitudes can constrain contrasts across the Moho accurately enough to be utilized in geological interpretation.
 Publication:

Geophysical Journal International
 Pub Date:
 October 2007
 DOI:
 10.1111/j.13652966.2007.03502.x
 Bibcode:
 2007GeoJI.171..286J
 Keywords:

 density;
 Moho discontinuity;
 seismic velocities