Active seismoelectric exploration of glaciers

Abstract

[1] Repeatable and strong seismoelectric signals were recorded on Glacier de Tsanfleuron, Switzerland, using a vertical sounding geometry. Electromagnetic waves are inferred to be generated by electrokinetic conversion of seismic energy within the snow pack and near the dry-wet ice and ice-bed interfaces. A simple gradient-based scheme allows such electrokinetic interface responses (EIRs) to be isolated from noise. EIRs depend sensitively on the azimuthal orientation of the receiving array of electrical dipoles. Seismoelectric techniques promise to allow mapping even of thin water-bearing strata within or beneath glaciers or frozen ground, estimation of hydraulic or fluid properties of such strata, as well as monitoring of ice fracturing or basal properties and processes at improved spatial resolution.

A Critical Review of the Low-Frequency Electrical Properties of Ice Sheets and Glaciers

“…Pending elementary research to varying degrees, there are many unique opportunities for low-frequency electrical measurements to support studies of glacier dynamics and fracturing, including, e.g., [a] estimation of ice temperature, a key control on ice rheology (e.g., Paterson, 1994), from surface-based electrical resistivity or airborne transient EM (TEM) soundings; [b] permanent emplacement of strings of closely spaced electrodes in boreholes, together with manual or automated resurveying, for longer-term measurement of ice deformation (e.g., Borovinskiy, 1958) or the effects of seasonal temperate changes on ice properties by exploiting electrical freezing potentials (e.g., Parameswaran and Mackay, 1996); [c] estimation of water content in temperate ice using low-frequency methods such as e.g., capacitively coupled resistivity (e.g., Kuras et al, 2006), joint inversion of surface-based TEM and electrical resistivity sounding data (e.g., Sharma and Kaikkonen, 1999), or nuclear magnetic resonance (NMR), which has been popular in sea ice studies for some time (e.g., Callaghan et al, 1999), with a view to ultimately inverting jointly seismic, radar, and low-frequency electrical data towards improved estimation of water content in temperate ice; [d] the use of passive seismoelectrics for monitoring of fracturing events in ice or stick-slip events of basal motion using dense surface arrays of electrodes, which are financially much less restraining than the deployment of seismometers; and [e] the use of active seismoelectrics to detect thin layers within or beneath ice masses, and delineation and characterisation of the hydromechanical properties of either thinner or thicker layers in the englacial-subglacial system (e.g., Kulessa et al, 2006a).…”

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

“…The interface between snow and ice at about 22 m depth, with a difference in seismic velocity from 960 to 3650 m s −1 , was identified by an IR detection (Kulessa et al, 2006). Moreover, the ice-bed (limestone) interface at about 95 m depth also induced an IR.…”

SH Seismoelectric Response of a Glacier: An Analytic Study

“…Therefore, this method could constitute a prospecting tool for the detection of the interface between the glacier and the underlying water‐saturated sediments. Kulessa et al () conducted the first—to the authors' knowledge—seismoelectric field test on a glacier, namely, the Tsanfleuron glacier, located in the Swiss Alps. They recorded strong seismoelectric signals and interpreted them as conversions within the snow pack and near the dry‐wet ice and ice‐bed interfaces.…”