Cross-Hole Seismic Testing
This test needs of two boreholes minimum for its execution. For this method we generate P and S wave seismic pulses in the emission borehole and we record the travel times with triaxial geophones in the second borehole. It is possible to know the velocity of the medium through which the waves propagate knowing the distance that separates the probes. It is also possible to know the density of the materials through which the test was realized.

Applications
-This method allows us to gauge the dynamic elastic modules, Poisson's modulus, Young's modulus, Shear modulus, among others.
-Cross Hole seismic tomography is used when we require to know the distribution of P waves on a very precise scale. The level of uncertainty given by the obtained models is highly reduced, given that the distribution of sources and receptors allow for homogeneous reading of data. Besides the presence of low velocity layers do not compromise this methodology. It is also possible to enhance the resolution of the superficial layers of the investigated terrain using geophones in the surface of said terrain.