The easiest way to explain what we are about is to use the all knowing Wikipedia. They have this to say about ground geophysics:
Exploration geophysics. Exploration geophysics is an applied branch of geophysics, which uses physical methods, such as seismic, gravitational, magnetic, electrical and electromagnetic at the surface of the Earth to measure the physical properties of the subsurface, along with the anomalies in those properties.
We’ll break that down into the much smaller parts over the coming weeks so you can really get a feel for what we are about.