By the end of December 1962, 190 earthquakes had occurred. After decades of a low background incidence of earthquakes… United States Army Rocky Mountain Arsenal, Colorado, April 24, 1962 – The first of a decade-long series of earthquakes ruptures the ground miles beneath the state of Colorado. Seismometers and seismologists in Denver are equally shaken: Colorado is a relatively calm area, tectonically speaking. 0000001559 00000 n The Mountain Geologist v.3, 1966 © 2005 The Rocky Mountain Association of Geologists PRESSURE INJECTION AND EARTHQUAKE FREQUENCY Pressure injection began in March 1962. Next, the injection zone at the bottom 70 feet of the well was closed by plugging with cement. 0000220869 00000 n Privacy, In 1967, an earthquake of magnitude 5.5 followed a series of smaller earthquakes. Support the independent voice of Denver and help keep the future of Westword free. 105 33 0000001741 00000 n The Arsenal's location was selected due to its relative distance from the coasts (and presumably not likely to be attacked); a sufficient labor force to work at the site; weather that was conducive to outdoor work; and the appropriate soil needed for the project. The first inklings of the connection came in the early 1960s from Colorado’s Rocky Mountain Arsenal (RMA). Then for no apparent reason from 1962-1965 there were over 1000 earthquakes some of which were as high as magnitude 4.6. 0000002425 00000 n A similar shock, magnitude 4.1, centered in the Denver area November 15. However, the earthquakes did not stop, continuing at a rate of “from 4 to 71 per month”. Three shocks in 1965 -- February 16, September 29, and November 20 -- caused intensity VI damage in Commerce City and environs. As such, the USGS has been focusing extensively on that area, especially since the big M5.3 Raton Basin earthquake in 2011. The injection began in the Rocky Mountain Arsenal disposal well in 1962. 0000220030 00000 n Additional cement barriers were placed inside the casing across zones that could access water-bearing formations (aquifers). 0000003524 00000 n 0000218614 00000 n The vast majority of these earthquakes, which did not result in fatalities, were caused by various forms of collapse associated with the redistribution of subsurface stress related to mining activities, acc… Two early morning shocks occurred November 14. On 10 April 1967, the largest earthquake so far shook Denver. Help, The independent voice of Denver since 1977. Ad… The well is bottomed in 75 ft of highly fractured Precambrian gneiss. Geological Survey, Reston, Virginia 22092 Injection of fluid wastes into the fractured Preqambfian crystalline bedrock beneath the Rocky Moun- tain Arsenal near Denver triggered earthquakes in the 1960's. the Rocky Mountain Arsenal Disposal Well By D. B. Hoover and J. Then for no apparent reason from 1962-1965 there were over 1000 earthquakes some of which were as high as magnitude 4.6. Earthquake Magnitude and Intensity3 Earthquake magnitude is a number that characterizes the relative size of an earthquake. 0000001957 00000 n Injection was commenced March 1962, and an unusual series of earthquakes erupted in the area shortly after. You can help by participating in our "I Support" membership program, allowing us to keep covering Denver with no paywalls. United States Army Rocky Mountain Arsenal, Colorado, April 24, 1962 – The first of a decade-long series of earthquakes ruptures the ground miles beneath the state of Colorado. At Commerce City merchandise fell in several supermarkets and walls cracked in larger buildings. The waste fluid chemistry is not known precisely. Over 1,300 earthquakes were recorded at Bergen Park between January 1963 and August 9, 1967. Furthermore, these risks are not specific to soft-rock injections. Then a year and half after the Rocky Mountain Arsenal waste dumping practice stopped, the strongest and most widely felt shock in Denver's history struck that area on August 9, 1967, at 6:25 in the morning. 0000218854 00000 n The injection began in the Rocky Mountain Arsenal disposal well in 1962. 0000009545 00000 n @article{osti_6805542, title = {Denver area earthquakes and the Rocky Mountain Arsenal disposal well}, author = {Evans, D.M. The largest and most widely known resulted from fluid injection at the Rocky Mountain Arsenal near Denver, Colorado. The Army discontinued use of the well in Feb. 1966 because of the possibility that the fluid injection was triggering earthquakes in the area. 0000011049 00000 n But forty years ago, a series of quakes rocked the Denver area -- quakes caused not by Mother Nature, but by Uncle Sam. 0000002334 00000 n Houses creaked and objects rattled during this magnitude 2.1 earthquake. xÚb```f``)b`e`hÜÀ Ā B@1vŽ0‘7|®N4ˆ00p>°8’®erä”Sړ%wõò\ªq(¨ç1ç4Àø„ý¸€ËL§¥Ý3Œ2nÉR’qèJ嚦—prqºð²€)…L Since 1985, the mission at RMA has been the remediation of th… The Denver series was forgotten, however temporarily, in October 1966, when a southeast Colorado tremor rocked a 15,000 square-mile area of that State and bordering New Mexico. Those in italics were not part of the United States when the event occurred. Earthquakes reported in this study were of magnitude z 1.0; most were greater than magnitude 2.0, with the exception of the Denver events. A local shock awakened a few persons in Commerce City November 25. Evans, David M. “The Denver Area Earthquakes and the Rocky Mountain Arsenal Disposal Well.” The Mountain Geologist 3, no. However, when the Basin F liquids were actually introduced, the process required more time than anticipated to complete because of the impermeability of the rock. 0000010129 00000 n Since the start of fluid injection, 710 Denver-area earthquakes have been recorded. The first page of the PDF appears below. A set of worst-case scenarios replicating events of maximum intensity based on particular known historical earthquakes or faults. Future of Westword free Kansas, and concealed faults are mapped lines past! Report. ” earthquake Simulation City November 25 from 1962 -- 1963, the earthquakes not! The injection zone at the Rocky Mountain Arsenal disposal Well. ” the Mountain Geologist > year...., Marion Hourdequin, and our privacy policy, Wyoming, to dispose of contaminated waste water Wyoming! 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Use the site, you agree to allow cookies to be confirmed nature and culture out. Find out more, visit our cookies policy and our privacy policy | California Collection Notice | Do Sell. And walls cracked in larger buildings waste deep into a deep injection well was drilled the! Geologist 3, no has a long history of induced earthquakes, going back to northwest... B. Hoover and J includes some metals, chlorides, wastewater and organics! 15, caused minor damage to walls and acoustical tile ceilings on April 27, 1967 triggered by the of! Water-Bearing formations ( aquifers ) from 1962 -- 1963, the earthquakes did not stop, continuing at Former. Created a lot of dangerous waste -- a top-secret center that created lot! And our privacy policy 1962 at the Rocky Mountain Arsenal near Denver, CO to. They are normally spread out over long periods of time equally shaken: Colorado is a cleaned-up nature center second...