Ground-penetrating radar (GPR) and microgravimetric surveys have been
conducted in the southern Jura mountains of western Switzerland in
order to map subsurface karstic features. The study site, La Grande
Rolaz cave, is an extensive system in which many portions have been
mapped. By using small station spacing and careful processing for
the geophysical data, and by modeling these data with topographic
information from within the cave, accurate interpretations have been
achieved.
The constraints on the interpreted geologic models are better when
combining the geophysical methods than when using only one of the
methods, despite the general limitations of two-dimensional (2D)
profiling. For example, microgravimetry can complement GPR methods
for accurately delineating a shallow cave section approximately 10
X 10 mt in size. Conversely, GPR methods can be complementary in
determining cavity depths and in verifying the presence of off-line
features and numerous areas of small cavities and fractures, which
may be difficult to resolve in microgravimetric data.