Scientists in California and Oklahoma built a rotary earthquake simulator that spins and stores energy inside a 500-pound flywheel. Its 100 HP three-phase electric motor provides
torque up to 3,000 Nm at any velocity from zero to 3,300 RPM, and it can accelerate to full rotation speed in 0.1 seconds. As it spins, a fast-acting (30 millisecond) clutch grabs a disc-shaped piece of rock and presses it against the flywheel, which forces the rock to rotate with the spinning hunk of metal. It moves until all the kinetic energy dissipates, which the researchers called an "earthquake-like slip event."