There is no universally best method. Survey choice depends on target depth, geometry, geology and expected physical-property contrasts. Magnetic, gravity, electrical, electromagnetic, seismic and other methods can be complementary. ADR can be evaluated as an additional pre-drill dataset.

Groundwater investigations commonly use electrical and electromagnetic methods because water, salinity, lithology and pore structure affect electrical properties. Resistivity, ERT, TEM/TDEM and other EM approaches are among the methods used.

Geothermal exploration can integrate geology, geochemistry, gravity, magnetics, seismic and electrical/electromagnetic methods such as magnetotellurics. The appropriate combination depends on the geothermal system and uncertainty being addressed.

Generally, no. Geophysics provides indirect measurements and models. Drilling remains critical for direct geological samples, assays, temperature, permeability, flow testing and other ground truth. The opportunity is to improve information before drilling.

An EM survey measures how the subsurface responds to electromagnetic fields. Different EM techniques use different sources, frequencies, geometries and processing approaches and can be sensitive to conductivity, resistivity and related geological or fluid contrasts.

Depth depends on the method, survey design, geology, physical properties, signal-to-noise conditions and target. Some methods are shallow; others investigate kilometre-scale geology. Depth capability should be assessed project by project.

Geophysical methods infer subsurface conditions from physical measurements collected at or above the surface. They do not literally see through rock; they measure responses that can be modelled and interpreted in geological context.

VEXRAD uses the term for a depth-referenced subsurface interpretation derived from surface-acquired ADR measurements. It is intended to inform the decision before drilling and should be integrated with other geological and geophysical evidence.