Ultrasonic laboratory measurements on spherical samples -: A tool for the investigation of seismic anisotropy in rocks

Ultrasonic measurements on spherical samples provide a good tool for the investigation and understanding of seismic anisotropy at laboratory scale. Single geological elements, like layering or fractures, often create an anisotropy with a transversely isotropic symmetry. For this case the elastic tensor can be fully described by five independent elastic constants. This can be effectively achieved with laboratory measurements on cylindrical sample. For lower seismic symmetries, created by the superposition of more than one geological element, nine or even thirteen independent constant are necessary, and therefore more independent velocity measurements. In these cases spherical samples add an useful tool in the box of seismic laboratory techniques.