This volume contains several contributions among those held at the fourth Course of the International School of Applied Geophysics, Erice, March 15-24, 1982. The content has been arranged according to the three main topics covered during the course: the goedynamic models, the contribution of geophysics to their construction and the optimization and constrains of the exploration methods. At the end of the volume, four short notes are published, written by participants to the course and related to the general subject. It is regrettable that not all the lectures and discussions are available for...