Anatomy of a seismoelectric conversion: Measurements and conceptual modeling in boreholes penetrating a sandy aquifer

Abstract

[1] Conversions of compressional seismic waves to electric fields have been measured in two boreholes drilled in an unconfined sandy aquifer on the Gnangara Mound near Perth, Australia. The seismoelectric conversions at both field sites occurred in the vicinity of the water table at 13-m depth and yielded maximum amplitudes of 1 mV/m using a sledgehammer source on surface. Partially cemented layers, inferred from geological and geophysical logs, straddle the water table and may play a role in generating the conversion and influencing its amplitude distribution. The dense vertical sampling used in these borehole experiments reveals spatial and temporal polarity reversals of the interfacial signal which provide new evidence in support of the conceptual model for seismoelectric conversions at interfaces. We demonstrate that the growth rate of the source zone and its maximum vertical extent below the water table are encoded in the polarity of the interfacial signal. These experiments confirm that vertical seismoelectric profiling can be used to gain further insight into seismoelectric conversions and characteristics of interfaces that makes them amenable to detection.

Laboratory measurements and theoretical modeling of seismoelectric interface response and coseismic wave fields

“…[3][4][5][6][7] Furthermore, a wide range of field and laboratory validations of the coseismic field and the interface response was presented in the literature. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] Several of these works compare either field measurements 15,17 or laboratory measurements 20 with a seismoelectric wave propagation model, corroborating that the coseismic and interface response fields are predicted by the theory.…”

Semiautomatic and Automatic Cooperative Inversion of Seismic and Magnetotelluric Data

“…As a sidenote, the links we described between seismic and EM information required for joint or cooperative inversion should not be confused with the seismo-electromagnetic phenomena in which a tiny portion of the seismic wavefield is converted to an electromagnetic wavefield or vice versa (Dupuis et al 2009;Garambois and Dietrich 2002).…”

Electrokinetic Techniques for the Determination of Hydraulic Conductivity

“…Then signal processing needs filtering techniques such as Butler & Russell (1993). The advantage of this method is to detect the contrasts of permeability at depth from few meters to few hundreds of meters (Dupuis & Butler, 2006;Dupuis et al, 2007;Dupuis et al, 2009;Haines, Guitton & Biondi, 2007;Haines, Pride, Klemperer & Biondi, 2007;Strahser et al, 2007;2011;Thompson et al, 2005).…”