Fault

Although the most devastating earthquakes occur in nature, humans have been able to learn more about faults and earthquake mechanisms since we have had the power to produce earthquakes ourselves. Nuclear weapons testing in the desert near Los Alamos, New Mexico, was the first known human activity to produce measurable earthquakes that were found to propagate along existing faults. Our ability to build major dams that retain huge quantities of water has also generated earthquakes by so-called "hydrofracturing," in which the weight of the water stresses fractures in the underlying rock. Pumping of oil and natural gas from deep wells and the disposal of liquid wastes through injection wells have also produced small motions along faults and fractures.