Seismoelectric Surface-Wave Analysis for Characterization of Formation Properties, using Dispersive Relative Spectral Amplitudes

We study seismoelectric (SE) surface-wave signals and find that they can be used to infer changes in the SE coupling properties at depth. Seismoelectric surface-wave signals have much higher amplitudes than seismoelectric body-wave signals. We propose to measure both the seismic and the electrical potential or electromagnetic (EM) field along the surface of the Earth. We use Dispersive Relative Spectral Amplitudes (DRSA) that measure the frequency-dependent relative strength of electrical signals versus seismic signals associated with seismoelectric surface-wave signals. We show that the DRSA have sensitivity to contrasts in the electrokinetic coupling coefficient and other relevant petrophysical properties at depth. Our discovery can mitigate the major limitation that plagues body wave-based SE methods: the relative weakness of the converted, EM signals from seismic body waves. We envision applications to characterize subsurface rock, fluid and fluid-flow properties (e.g. porosity, permeability, and dynamic fluid viscosity, salinity) in the near surface, for aquifers, and shallow geothermal reservoirs.

To the estimation of damping of seismic body waves in the Elbrus volcanic area

The problem of the origin and development of hazardous endogenous processes in the southern regions of Russia is considered. According to the results of the analysis of data obtained by means of the regional seismic network, there were estimated the Q-factor of the layered geophysical medium as well as damping of elastic body waves. The new results testifying in favor of the hypothesis on the likely area of upcoming fluid-magmatic processes in the Elbrus volcanic region are considered.