29 August, 2011 (4pm), 5 Merrion Square, Dublin 2

Speaker: Gavin Menzel-Jones, University of British Columbia, Canada
Title: Seismoelectric Modelling of the Flux-Normalized P-SV-TM Propagation Mode

Abstract:

Elastodynamic and electromagnetic processes are coupled together in saturated, porous media, by a phenomenon known as the electrokinetic effect. In horizontally layered media, the seismoelectric system, which contains the coupled elastodynamic and electromagnetic systems, can be separated into two independent modes of propagation: SH-TE and P-SV-TM. The SH-TE mode contains horizontally polarized shear waves coupled with transverse electric polarized electromagnetic waves. In the P-SV-TM mode, both fast and slow compressional waves are coupled with vertically polarized shear waves and transverse magnetic polarized electromagnetic waves. The seismoelectric system can be expressed in the form of both the two-way and one-way wave equations. By applying the principle of normalizing energy flux across boundaries, the matrix amplitude balance of the system is improved and both one-way and two-way reciprocity theorems can be implemented. We carried out full-waveform modelling of the flux-normalized P-SV-TM seismoelectric system in a 2-D fluid-saturated horizontally-stratified porous media. Both one-way and two-way wavefields were modelled, allowing the composition of one-way wavefields into two-way wavefields to be clearly observed. We investigated both the generation of electromagnetic fields due to the propagation of a seismic perturbation and the generation of seismic waves due to the propagation of a diffusive electromagnetic wave.