Geological noise in near-surface electromagnetic induction data

Near-surface and Topographic Distortions in Electromagnetic Induction

The most revealing description of electromagnetic (EM) distortions due to near-surface inhomogeneities and topography is in terms of galvanic and inductive effects. In either case, the distorted electric ankt magnetic fields can be best visualized as a vectorial sum of primary and secondary fields. Secondary electric fields due to electric charge build-up in the galvanic case persist to the lon...

Detection and classification from electromagnetic induction data

In this paper we introduce an efficient algorithm for identifying conductive objects using induction data derived from eddy currents. Our method consists of first extracting geometric features from the induction data and then matching them to precomputed data for known objects from a given dictionary. The matching step relies on fundamental properties of conductive polarization tensors and new ...

Electromagnetic Induction Sensor Data to Identify Areas of Manure Accumulation on a Feedlot Surface

Distance field computation for geological slab surface data sets

The three-dimensional shapes of tectonic plates that sink into the Earth’s mantle (slabs) are the starting point for a range of geoscience studies, from determining the forces driving the motion of tectonic plates, to potential seismic and tsunami hazards, to the sources of magmas beneath active volcanos. For many of these applications finite element methods are used to model the deformation or...

Invertibility of current density from near-field electromagnetic data

The problem of determining a current density confined to a volume from measurements of the magnetic and electric fields it produces exterior to that volume is known to have nonunique solutions. Despite the nonuniqueness of the inversion we show that one may nevertheless uniquely determine certain moments of the vector spherical harmonic expansion of the current. It is demonstrated that the dete...