Three-dimensional seismic endoseopy - Part I: Design of apparatus and basic imaging algorithms

A method, called "seismic endoscopy," able to perform three-dimensional (3- D) acoustical imaging in a cylindrical volume around shallow-depth borehole s is described. The main characteristics of borehole tools designed and con structed in our laboratory are presented. Several tests performed in an aco ustical water tank are used to illustrate the basic imaging algorithms adap ted to the particular acquisition geometry of the probes. In particular, bo th the filtering of borehole waves and azimutal refocusing are discussed.