A subsurface imaging cable includes a plurality of sensor modules, wherein the
plurality of the sensor modules are flexible and each of the plurality of the sensor
modules is spaced apart on the subsurface imaging cable at a selected distance;
and a flexible medium connecting the plurality of the sensor modules, wherein the
subsurface imaging cable is flexible and adapted to be wound on a reel. A method
for subsurface images includes acquiring direct-current measurements at a plurality
of sites in a survey area; acquiring a first set of electric and magnetic measurements
from natural electromagnetic fields at the plurality of sites; acquiring a second
set of electric and magnetic measurements using controlled electric and magnetic
sources at the plurality of sites; and determining a subsurface conductivity distribution
from the direct-current measurements and the first set and the second set of electric
and magnetic measurements.