What lies beneath our feet? This module addresses this question by exploring how waves, rays and the various physical techniques are used in geophysics to image the subsurface on scales of meters to kilometers. The basic theory and interpretation methods of seismic, electrical and gravity and magnetic surveys are studied. A wide range of applications is covered including archaeological geophysics, energy resources and geohazards. Students doing this module are normally expected to have a good mathematical ability, notably in calculus and algebra before taking this module (ENV-1A61 Mathematics for Scientists I, ENV-1A62 Mathematics for Scientists II or equivalent).