The beginning of the beginning–-Foundations of injection-induced seismicity

Injection-induced seismicity has a long history in Colorado and one that is directly tied to the Rocky Mountain Association of Geologists (RMAG) and The Mountain Geologist. Two foundational cases of injection-induced seismicity are the Denver earthquakes from 1962 to 1968, caused by injection at the Rocky Mountain Arsenal near Denver, Colorado, and the Rangely experiment that took place in the Rangely oil field, Colorado from 1969 to 1974. The deep disposal well at the Rocky Mountain Arsenal disposed of hazardous waste associated with chemical weapons and chemical production. Shortly after injection began, earthquakes commenced in an area that had not witnessed an earthquake in almost 100 years. The Denver earthquakes ranged in magnitudes up to a M5.3 that occurred after injection had ceased at the disposal well. The lessons learned during this instance of injection-induced seismicity were taken to Rangely to conduct experiments on controlling earthquakes through the perturbation of pore fluid pressure. The USGS conducted the Rangely experiment by alternating periods of injection and pumping in four wells within the Rangely oil field. Seismicity and pore pressure were monitored throughout the experiment to determine whether the changes of fluid pressure could control the earthquakes. They found that the Hubbert-Rubey principle, described in 1959, did account for injection-induced seismicity and that earthquakes could be controlled through pore pressure manipulation. The research associated with these cases is the foundation on which all later injection-induced seismicity research rests. The 100-year anniversary of RMAG is an appropriate time to revisit these cases, the original research, and the studies that have followed.