A method, system, and electrode assembly are disclosed that maximizes the lifetime of electrodes for high energy electrical discharges in water by arranging the electrodes in concentric rings or a stack of concentric rings. The radii and the thickness of the ring electrodes are optimized for electrical reliability, low jitter, and minimal erosion. In one embodiment, the electrode assembly is configured to be disposed in a subterranean dielectric medium, receive an electric current pulse having a length of time greater than 100 microseconds, and form an electric arc between the first electrode and the second electrode, thereby producing a pressure pulse axially away from the insulator.