Seismoelectromagnetic homogeneous space Green’s functions

Abstract

We have developed explicit expressions and the corresponding computer code for all homogeneous space Green’s functions for coupled electromagnetic fields and poroelastic waves. The Green’s functions are derived from the basic equations in closed form in the wavenumber- and space-frequency domains. They are given for point sources of any type. This adds several Green’s functions to what has been published before. These Green’s functions can be used in integral equation formulations, for numerical model validation, and for studying earthquake-related electrokinetic effects. The wavenumber domain code for all Green’s functions is given with the numerical test on the basic equations to demonstrate correctness. The numerical codes to compute them in the space-frequency domain are also given. A numerical inverse fast Fourier transformation routine is used to provide space-time domain results. At seismic frequencies, the fast P-wave is radiated with the largest amplitude in all fields, except for the magnetic fields where no P-waves are generated. At ultrasonic frequencies and in the particle and filtration velocity fields generated by an electric current source, the slow P-wave has the strongest amplitude. In the filtration velocity and particle velocity, the slow P-wave is, respectively, three orders and one order of magnitude stronger than the fast P-wave.