Electromagnetic and Seismoelectric Sensitivity Analysis Using Resolution Functions

Abstract

SUMMARYFor multi-parameter problems, such as the seismoelectric system, sensitivity analysis through resolution functions is a low-cost, fast method of determining whether measured fields are sensitive to certain subsurface parameters. We define a seismoelectric resolution function for the inversion of a bulk density perturbation. The synthetic data and Green's functions required to construct the resolution function are computed using the seismoelectric modelling code ESSEMOD. First, we consider the purely electromagnetic problem with a conductivity perturbation at a single point in an isotropic homogenous half-space. The result is nearly identical to a published result based on analytical Green's functions. It correctly maps the position of the scatterer. Next, we perform an electromagnetic sensitivity analysis for the case of a layered background medium. Again, the resolution function is capable of correctly mapping the scatterer when it is above as well as below a layer of increased conductivity; although in the latter case with less resolution. Finally, we generate multi-component synthetic data with our forward modelling code and compute the seismoelectric resolution function for inversion of a bulk-density perturbation. We find that the seismoelectric system is sensitive to a perturbation in bulk density and that the position of the perturbation can be correctly recovered.

Comparison of eigenvectors for coupled seismo-electromagnetic layered-Earth modelling

“…We have already predicted this behaviour by looking at eqs (F35) and (F36). For additional electromagnetic comparisons of ESSEMOD using the GST eigenvector set with independent electromagnetic modelling codes, the reader is referred to Grobbe et al (2014) and Maas et al (2015).…”

A review on electrokinetically induced seismo-electrics, electro-seismics, and seismo-magnetics for Earth sciences

“…The authors concluded that the model parameters are better determined for the joint inversion of seismic and electrical data by comparison with the inversion of the seismic time-series alone. Maas et al (2015) have carried out a sensitivity analysis using resolution functions as structured first steps towards inversion.…”