Certified by.......-.-------------------------- SThesis Supervisor Accepted by........................ *

When rock is deformed in compression, small scale crack-ing, i.e. microfracturing, occurs. Each microfracture ev-ent rai ates elastic energy in a manner analogous to earth-quakes. A broad study of many aspects of the microfract-uring process was made by detecting and analyzing these radiations with a new type of instrumental system. Micro-fracturing activity was compared with macroscopic strain measurements and it was found that it is ciosely related to the inelastic stress-strain properties of brittle rock. Dilatancy could be entirely attributed to microfractur-ing. The microfracturing that occurs during fractional sliding or ductile deformation are very similar but dif-fer markedly from that which occurs in brittle rock. Mar-ble was found to undergo a transition from cataclastic to fully plastic flow as the confining pressure was increase