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Kansas Geological Survey Public Information Circular 36 • April 2014 : The Potential for Triggered in Rex C. Buchanan, K. David Newell, Catherine S. Evans, and Richard D. Miller, Kansas Geological Survey

Introduction activity in the ’s crust is known as seismicity. When linked to activities, it is commonly referred to as “induced seismicity.” Industries that have been associated with induced seismicity include oil and gas production, , geothermal energy production, construction, underground nuclear testing, and impoundment of large (National Research Council, 2012). Nearly all instances of induced seismicity are not felt on the surface and do not cause damage. In the early 2000s, concern began to grow over an increase in the number of earthquakes in the vicinity of a few oil and gas exploration and production operations, particularly in , Arkansas, Ohio, , and . Figure 1—Earthquake hazard maps show the probability that ground shaking, or motion, will Horizontal drilling in conjunction exceed a certain level, over a 50-year period. The low-hazard areas on this map have a 2% chance with has often of exceeding a low level of shaking and the high-hazard areas have a 2% chance of topping a much been singled out for blame in the greater level of shaking (modified from USGS, 2008). public discourse. Hydraulic fracturing, popularly called “fracking,” does of wells currently in operation have recorded near disposal wells starting cause extremely low-level seismicity, been suspected of inducing earthquakes in September 2013, about three years too small to be felt, as do explosions large enough to be felt or cause damage after horizontal drilling activities in the associated with quarrying, mining, dam (National Research Council, 2012). Mississippian limestone play—and building, and other industrial activities. Most often, detected seismic activity associated water disposal—had crossed Although the actual process of associated with oil and gas operations over the state line into Kansas from hydraulic fracturing has been suspected is thought to be triggered when Oklahoma. However, the region also of inducing larger earthquakes a few wastewater is injected into a disposal experienced several small historical times worldwide, the U.S. Geological well. In the disposal process, waste earthquakes long before the increased oil Survey has found no evidence to products—such as saltwater produced activity, making it difficult to determine suggest that it has contributed much with oil and gas and recovered the cause of the recent seismic events. to increases in the rate of earthquakes hydraulic fracturing fluids—are injected Although some areas of Kansas are at (Hayes, 2012). into deep and confined porous rock. greater risk of seismicity than others, Felt earthquakes associated with any Identifying a link between whether natural or induced, none of oil and gas production activities are earthquakes and human activities the state is in a high-hazard earthquake rare. In the , only a small is difficult. Complex subsurface zone (fig. 1). fraction of the hundreds of thousands geology and limited data about that Scientists continue to monitor and geology make it hard to pinpoint evaluate possible instances of induced Terms in bold are defined in the glossary. the cause of many seismic events seismicity. In states with significant in the midcontinent, particularly in increases in seismic activity, including regions historically prone to naturally Oklahoma, monitoring has increased in occurring low-level seismic activity. localized areas where unusually high In south-central Kansas, for example, rates of seismicity have occurred near several small earthquakes have been oil and gas production activities. To help reduce the potential for induced Measuring Earthquake Magnitude precisely comparable, they can, in seismicity related to the rate of injection and Intensity general, be correlated when intensity of wastewater into disposal wells, Earthquakes can be measured in two measurements nearest the are scientists and others have developed different ways. One method is based used in the comparison (fig. 2; Steeples some best-practice recommendations on magnitude—the amount of energy and Brosius, 1996). Seismologists that would help prevent activation of released at the earthquake source. categorize earthquakes by their stressed faults. The other is based on intensity—how magnitude, not by their perceived much the ground shakes at a specific intensity. Natural vs. Induced Seismicity location. Although several scales Earthquakes and the Potential Most seismic activity occurs when have been developed over the years, for Induced Seismicity in Kansas within the Earth’s crust causes the two commonly used today in the a or faults in subsurface rocks United States are the Modified Mercalli The majority of seismic events are to slip and release enough energy to scale, which measures intensity, and microearthquakes, too small to be generate tremors. The vast majority of the , which felt or to cause damage. The largest earthquakes are instigated naturally measures magnitude (M), or size. documented earthquake in Kansas, and generally happen where the Earth’s The moment magnitude scale is now centered near Wamego east of tectonic plates interact. For the United preferred to the older, more familiar Manhattan in 1867, rocked buildings, States, that means most seismic activity Richter scale because it overcomes some cracked walls, stopped clocks, broke windows, and reportedly caused ground is on the west coast along the boundary of the limitations of the Richter scale between the Pacific and North American to sink and endanger the bank of a canal (USGS, 2014). plates. near Carthage, Ohio (Parker, 1868). That Measurements on the moment Away from plate boundaries, earthquake was likely associated with magnitude scale are determined using earthquakes are most often triggered the Nemaha Ridge, a 300-million-year- a complex mathematical formula when geological processes, such as the old buried mountain range extending to convert motion recorded with deposition and erosion of surface rock, roughly from Omaha to Oklahoma City. a into a number that alter the balance of opposing stresses The Humboldt fault zone on the eastern represents the amount of energy on subsurface rocks. Change in stress boundary of the Nemaha Ridge is still released during an earthquake. Energy increases or decreases strain—the slightly active (Steeples and Brosius, released for each whole number amount of rock deformation brought 1996). Based on damage and reports, the measurement is about 31 times greater about by stress—which weakens the Wamego earthquake was estimated to than that released by the whole number stability of faults confined by the have a magnitude of 5.2 (Niemi et al., before (USGS, 2014). The smallest stress. Faults may then slip and release 2004). Smaller faults and fault systems earthquakes recorded today have pent-up energy, which rolls in waves also have been identified in the state, negative magnitudes (e.g., M -2.0) on through the Earth’s crust (Ellsworth, mainly during oil and gas exploration, 2013). the moment magnitude scale because but none have been connected with large The U.S. Geological Survey estimates the scale’s range is based on that of the earthquakes. several million earthquakes occur Richter scale, developed in the 1930s At least 25 earthquakes in Kansas around the world each year, although when monitoring equipment was less were documented in newspaper many small ones go undetected (USGS, sensitive. Scientists are now able to accounts and other sources between 2014). Seismic events too small to detect earthquakes smaller in magnitude 1867 and 1976. A few of the later ones be felt on the surface are known as than the “0” used as the Richter scale were recorded with seismic equipment. microearthquakes, or microseisms. baseline. Between 1977 and 1989, the Kansas The term “induced seismicity” Measurements of intensity on the Geological Survey recorded more is popularly used for any seismic Modified Mercalli scale range from I than 200 small earthquakes with a activity linked to human activity. Some to XII and are based solely on damage temporary seismic network as part of researchers, however, more narrowly assessment and eyewitness accounts. a study to identify seismic risk in the define “induced seismicity” as seismicity Intensity measurements near the source state (fig. 3). The monitoring equipment caused solely by human activity and use of an earthquake are generally higher was sensitive enough to detect artillery the term “triggered seismicity” to define than those at a distance. They can also fire at Fort Riley from 30 miles (50 km) human activity that sets off a small remain high in the direction the waves away and large earthquakes as far away transient event, which then instigates of energy travel and may be magnified as Japan (Steeples and Brosius, 1996). or contributes to a larger earthquake in areas underlain by loose gravels and Today, two seismic monitoring stations, controlled by natural stresses (Cesca, unconsolidated sediments. Determining operated by the U.S. Geological 2012). Because the amount of influence a intensity can be difficult in sparsely Survey, are located in Kansas. One is human activity has on a seismic event is populated areas with few buildings at Cedar Bluff in western hard to establish, that distinction is not because intensity is calculated largely on Kansas and the other is at the Konza always made. “Induced seismicity” is the effects that tremors have on human- Prairie Biological Station south of used throughout this circular to refer to made structures. Manhattan in northeastern Kansas. The any seismic event influenced by human Although an earthquake’s magnitude Oklahoma Geological Survey monitors activities. and intensity measurements are not earthquakes in Oklahoma at about a 2 Prague and several other Oklahoma Modified Mercalli Intensity Scale Magnitude (approx.) locations with previous natural earthquake activity, however, has not M 3.0 & I Not felt except by a very few under especially under been confirmed (Oklahoma Geological favorable conditions. Below M 1 never felt. Harper Co., KS Sept. 2013 Survey, 2014). II Felt only by a few persons at rest, especially on M 3.0 – 3.9 * M 2.9 Before 2013, the only documented upper floors of buildings. Sumner Co., KS instance of possible induced seismicity III Felt noticeably indoors but not always recognized Dec. 2013 in Kansas occurred in 1989 when small as an earthquake. Vibrations similar to the passing M 3.8 of a truck. & Jan. 2014 earthquakes were recorded near Palco in * M 3.9 Rooks County, about 30 miles northwest IV Felt indoors by many, outdoors by few. Dishes, M 4.0 – 4.9 windows, doors disturbed. Standing vehicles rocked. Rooks Co., KS of Hays. The largest, a M 4.0, caused 1989 minor damage (Steeples and Brosius, V Felt by nearly everyone. Some dishes, windows * M 4.0 broken. Unstable objects overturned. 1996). Several injection wells used for clocks may stop. the disposal of wastewater—extracted Wamego, KS during conventional vertical oil well VI Felt by all. Some heavy furniture moved. Falling M 5.0 – 5.9 1867 plaster and chimneys. Damage slight. M 5.2 (estimated) operations—were located in the area, and one well in particular may have VII Damage varies from negligible in well-designed * Near and/or built structures to consequential in poorly built * Prague, OK been close to a deeply buried fault zone. and/or designed structures. M 6.0 – 6.9 Nov. 2011 Based on that well’s injection history, M 5.7 VIII Damage slight in well-designed structures, con- local geology, and low level of prior sequential in ordinary buildings. Chimneys, factory earthquake activity in the area, scientists stacks, and walls may fall. speculated that the seismicity could have IX Damage considerable in well-designed structures. M 7.0 and higher been induced (Armbruster et al., 1989). Partial collapse in substantial buildings. Buildings shifted off foundations. In 2013 and early 2014, several earthquakes were recorded in south- X Some well-built wooden structures destroyed; most masonry and frame structures destroyed with central Kansas in the vicinity of foundations. Rails bent. wastewater injection wells. In Harper XI Few, if any, masonry structures remain standing. County, a M 2.9 earthquake was Bridges destroyed. Rails bent greatly. recorded in September 2013, and in XII Damage total. Lines of sight and level are distorted. Sumner County earthquakes measuring Objects thrown into the air. M 3.8 and M 3.9 were recorded in December 2013 and February 2014, respectively (USGS, 2014). Whether Figure 2—The magnitude (M), or size, of an earthquake does not correlate directly with intensity oil activities played a role has not or damage, but an approximate comparison can be made between the magnitude and the felt been determined. Naturally occurring intensity and damages—enumerated on the Modified Mercalli Intensity scale—near the epicenter earthquakes have been recorded in the (USGS, 2014). region in the past, dating back to 1956. Further understanding of the complex dozen seismic stations, which also pick number of low-level earthquakes. subsurface geology in the region up some seismic events in Kansas. Similar-sized events go unrecorded in is needed to estimate what impact Although oil and gas drilling Kansas. wastewater disposal might have had. and production, and corresponding In Oklahoma, a number of seismic wastewater injection, increased in south- episodes are suspected of being Geology, Faults, and Induced central and western Kansas as interest in associated with induced seismicity. Seismicity the Mississippian limestone play grew, The largest, a M 5.7 earthquake, The Earth’s crust is full of fractures the state has not experienced the same was recorded near Prague in 2011 and faults. Under natural conditions, rise in seismic activity as neighboring (Keranen et al., 2013). Researchers are widespread faults deep in the crust are Oklahoma. That may be due to the investigating whether injected fluid able to sustain high stresses without lower level of drilling and production precipitated a M 5.0 that slipping. In rare instances, pressure from activity in Kansas, differences in then triggered the M 5.7 wastewater injected into deep wells can geology between the two states, or both. and thousands of along counteract the frictional forces on faults Oklahoma has historically had more the Wilzetta fault system in central and cause earthquakes (Hayes, 2012). In natural earthquakes than Kansas. Also, Oklahoma. The locations of the other words, fluid injected near a fault the Oklahoma Geological Survey, which foreshock, mainshock, and a M 5.0 can, in effect, change pore pressure—the has been monitoring seismic activity for suggest that three separate amount of pressure that fluid in a rock’s more than three decades, increased the portions of the complex fault system pores exerts on the rock—allowing a size of its monitoring network in 2009 were activated (Sumy et al., 2014). fault to move. (Oklahoma Geological Survey, 2014). A definitive connection between For that to happen, a combination of That led to the detection of a greater wastewater disposal and seismicity near human activities, natural conditions, and

3 do occur during hydraulic fracturing. In fact, geologists often record them to help identify the location of the newly made fractures and to measure stress. However, felt earthquakes have rarely been linked to hydraulic fracturing, and the ones that have been are relatively small (National Research Council, 2012). Two confirmed cases of felt seismic activity caused by hydraulic fracturing have been documented—a series of seismic events measuring up to M 2.3 in England in 2011 and a series of events ranging from M 2.2 to M 3.8 in a remote area of the Horn River Basin in , Canada, between 2009 and 2011 (Holland, 2013; BC Oil and Gas Commission, 2012). Hydraulic fracturing also has been suspected of causing a M 2.9 earthquake in south-central Oklahoma in 2011, but that has not been Figure 3—Historical earthquakes in Kansas before 1962 and seismic events recorded by the confirmed (Holland, 2013). Kansas Geological Survey between 1977 and 1989 (modified from Steeples and Brosius, 1996). Hydraulic fracturing is unlikely to cause felt seismicity because geologic events must occur at the same for wastewater storage. Formed 500 pressurization that occurs during the time. To begin, the Earth’s crust at the million or more years ago, the basement process usually lasts only a few hours site must be near a critical rock is overlain by thousands of feet of and affects only rocks in the area state of stress and an existing fault has sedimentary rock. Injected wastewater immediately surrounding the well bore to be nearby—within about 10 km (6 does not reach the basement rock, but (Zoback, 2012). Wastewater disposal, in mi). Most faults are small and only if pressure created by the injection which fluids are injected over a longer generate small earthquakes. For a fault of fluid is transmitted into the period, is more often associated with to slip and release energy, the location basement through surrounding rocks, induced seismicity. It has long been and orientation of the fault is critical. the potential for induced seismicity recognized that fluid injection can No matter how close a fault is to an increases (Ellsworth, 2013). trigger earthquakes. Seismic activity injection well, its orientation within the Because of their depth, faults within following wastewater disposal at ambient stress field and the properties the basement rock are hard to locate. the Rocky Mountain Arsenal near of the surrounding subsurface rocks Oil and gas exploration companies, Denver in the early 1960s and by water determine whether it has the potential which provide much of the data about injection at the Rangely oil field in to fail (National Research Council, 2012). the state’s subsurface geology, rarely western Colorado in the late 1960s If a fault does fail, the depth at which it drill that deep. Seismic-reflection and early 1970s has been well studied ruptures influences its effect. techniques used to identify subsurface (Zoback, 2012). However, although a Even when all the natural conditions rocks and faults are expensive and large quantity of fluids is injected into are favorable for induced seismicity near difficult to employ at that depth. Until hundreds of thousands of wells every a disposal well, an earthquake is not a more is known about the geology of year, only a small number of those wells certainty. Under most circumstances, Precambrian rocks, scientists will not have been associated with induced a significant amount of water must be be able to determine with certainty seismicity. injected over a prolonged period to what effect wastewater disposal and activate a fault. As fluid is injected into other oil and gas field activities have on Wastewater Injection and Class II the porous subsurface rock, the pore seismicity. A close spatial relationship Disposal Wells pressure would then have to increase to between a wastewater disposal site and There are approximately 172,000 fluid- the point that it caused the volume of the increased seismic activity, although it injection wells in the United States used rock to expand and destabilize a fault. raises legitimate questions, does not to dispose of wastewater or to extract Likewise, a decrease in pore pressure prove cause and effect. additional oil out of fields nearly when fluid is extracted from rock can depleted by traditional production affect fault stabilization (National Hydraulic Fracturing, Wastewater methods. Of those wells, designated Research Council, 2012). Disposal, and Induced Seismicity Underground Injection Control (UIC) Many of the Earth’s faults are in Hydraulic fracturing is at the center of Class II wells by the U.S. Environmental the Precambrian-age basement rock, the debate over induced seismicity in Protection Agency (EPA), about 20% are which in Kansas lies beneath the deep the United States. Microseisms, usually used for the disposal of saltwater that and confined porous formations used less than a magnitude of zero (M 0), is produced along with oil and natural 4 gas. In the disposal process, saltwater is increases that do occur from gravity An essential element of the injected into a deep formation selected injection are limited to the vicinity of traffic light system is the capacity to for wastewater disposal and not into the well, although the effects of gravity monitor seismicity and collect data. the formation from which it was injection may extend farther out than The current monitoring network in originally produced. Non-potable water anticipated. Force from fluid weight, the United States, with its widely and chemicals used in the hydraulic independent of injection pressure, also spaced stations in Kansas and many fracturing process, which must be can have an impact. other states, can detect moderate to disposed of under State of Kansas When fluids are pumped into a rock large earthquakes. However, it is less requirements, are also injected into formation under pressure, rather than effective at pinpointing the these wells. being allowed to flow more slowly of, or even recording, smaller events far Most of the rest of the Class II under the force of gravity, the added from monitoring stations. Determining wells are used during secondary and pressure may lower the frictional whether a connection exists between enhanced oil recovery operations resistance between rocks along an recent earthquakes and fluid injection to squeeze additional oil out of existing fault system. That allows the wells in Kansas and elsewhere will underground rocks (EPA, 2012). For rocks to slide. In the Rocky Mountain require increased and more densely these operations, saltwater is commonly Arsenal case, where chemical fluid waste spaced monitoring stations closer to injected back into the formation from was injected under pressure numerous injection sites. Increased access to data which it was produced. The injected times, seismic activity continued pertaining to the injection process, water, ideally, moves toward the for several years after injection was especially the volume of fluid injected production well, transporting additional discontinued (National Research over a specified period and the amount oil to the well. Council, 2012). of pressure used to inject it, is also vital. The EPA regulates the licensing and operation of Class II disposal wells Preventive and Remedial Measures References under the Safe Drinking Water Act or The authors of a National Research Armbruster, J. G., Steeples, D. W., and delegates authority to state agencies. Council (NRC) report and others Seeber, L., 1989, The 1989 earthquake The act is primarily designed to protect have suggested steps that could be sequence near Palco, Kansas: A aquifers and other drinking water taken to alleviate induced seismicity possible example of induced seismicity sources from contamination by injected associated with Class II wastewater (abstract): Seismological Research fluids. Class II well operators submit a disposal wells. The recommendations Letters, v. 60, no. 4, p. 141. form annually indicating total monthly are based on a protocol advanced BC Oil and Gas Commission, 2012, injected volumes and the maximum by the U.S. Department of Energy to Investigation of observed seismicity monthly recorded surface injection address induced seismicity associated in the Horn River Basin, http://www. pressure. with enhanced geothermal systems. To bcogc.ca/node/8046/download? The Kansas Corporation Commission establish a protocol in a specific location, documentID=1270&type=.pdf. (KCC) regulates the approximately an evaluation would first have to be Cesca, S., Dost, B., and Oth, A., 2012, 16,800 Class II wells in Kansas. About made to determine whether following Preface to the special issue “Triggered 5,000 of those wells are for wastewater suggested recommendations would and induced seismicity: Probabilities disposal and 11,800 for secondary and be feasible in that location. Enactment and discrimination”: Journal of enhanced oil recovery (KCC, 2014). would require coordination between , v. 17, no. 1, DOI 10.1007/ Class II wells are used only for the industry, government agencies, and s10950-012-9338-z. injection of fluids associated with oil and the research community; monitoring Ellsworth, W. L., 2013, Injection-induced gas production. Hazardous and non- seismicity and collecting data; assessing earthquakes: Science, v. 341, no. 6142, hazardous industrial waste, regulated hazards and risks; and developing DOI: 10.1126/science.1225942. by the Kansas Department of Health and mitigation plans (National Research EPA, 2012, Class II wells—Oil and Environment (KDHE), is disposed of in Council, 2012). gas related injection wells (class UIC Class I wells. There are 47 Class I The protocols are often referred to II): U.S. Environmental Protection wells in Kansas (KDHE, 2012). as “traffic light” systems. Under the Agency, http://water.epa.gov/type/ In general, waste fluids from oil and systems, operators would continue groundwater/uic/class2/ (accessed gas production in Kansas are injected injection as long as earthquakes March 27, 2014). back into deep subsurface formations did not occur (green light), would Hayes, D. J., 2012, Is the recent increase “under gravity.” That is, because the slow injection rates and take other in felt earthquakes in the central US formations can accept substantial precautions if seismicity occurred natural or manmade? U.S. Geological amounts of fluid, fluids are not injected (yellow light), and would abandon Survey, http://www.doi.gov/news/ under additional pressure but are wells if seismicity associated with doinews/Is-the-Recent-Increase-in- simply allowed to flow into these rock injection did not slow significantly Felt-Earthquakes-in-the-Central-US- formations under the force of gravity. or stop after precautions were taken Natural-or-Manmade.cfm (accessed Gravity injection limits the possibility (red light). In instances of suspected February 3, 2014). of pressure build-up in the disposal induced seismicity in Arkansas and Holland, A. A., 2013, Earthquakes formation and reduces the potential Texas, injection was terminated and triggered by hydraulic fracturing in for fault slippage. Often, any pressure seismicity subsided (Zoback, 2012). south-central Oklahoma: Bulletin of 5 the Seismological Society of America, v. technologies: National Academy of Sumy, D. F., Cochran, E. S., Keranen, K. 103, no. 3, p. 1,784–1,792. Sciences, 248 p. M., Wei, M., and Abers, G. A., 2014, KCC, 2014, Injection wells frequently Niemi, T. M., Ferris, A. M., and Observations of static Coulomb stress asked questions: Kansas Corporation Abers, G. A., 2004, Investigation of triggering of the November 2011 M5.7 Commission, http://www.kcc.state. microearthquakes, macroseismic data, Oklahoma earthquake sequence: ks.us/conservation/injection_wells_ and liquefaction associated with the Journal of Geophysical Research: Solid, faq.htm#2. 1867 Wamego earthquake in eastern 20 p., DOI: 10.1002/2013JB010612. KDHE, 2012, Information paper Kansas: Bulletin of the Seismological USGS, 2008, 2008 United States National addressing the potential for Class I Society of America, v. 94, no. 6, p. Maps: U.S. Geological disposal well operations in Kansas to 2,317–2,329. Survey, http://pubs.usgs.gov/ cause earthquakes: Kansas Department Oklahoma Geological Survey, 2014, fs/2008/3018/pdf/FS08-3018_508.pdf of Health and Environment, http:// OGS position statement—Oklahoma (accessed February 12, 2014). www.kdheks.gov/uic/download/ earthquake activity, February 17, 2014, USGS, 2014, Earthquakes Hazard UICI-IP-1.pdf. http://www.ogs.ou.edu/pdf/OGS_ Program—Earthquakes: U.S. Geological Keranen, K. M., Savage, H. M., Abers, G. POSITION_STATEMENT_2_18_14.pdf. Survey, http://earthquake.usgs.gov/ A., and Cochran, E. S., 2013, Potential Parker, J. D., 1868, Earthquakes in Kansas: earthquakes (accessed February 3, 2014). induced earthquakes in Oklahoma, The American Journal of Science Zoback, M. D., 2012, Managing the seismic USA—Links between wastewater and Arts, 2nd series, v. 45, no. 133, p. risk posed by wastewater disposal:

injection and the 2011Mw 5.7 earthquake 129–131. Earth, American Geological Institute, sequence: Geology, v. 41, no. 6, p. Steeples, D. W., and Brosius, L., 1996, http://www.earthmagazine.org/ 699–702. Earthquakes: Kansas Geological article/managing-seismic-risk-posed- National Research Council, 2012, Survey, Public Information Circular 3, wastewater-disposal (accessed February Induced seismicity potential in energy p. 1–6. 3, 2014).

Glossary Enhanced oil recovery—Production geographic setting that extends from matter, often deposited by wind of trapped oil left in the ground north-central Oklahoma into south- or water and then compacted into following primary and secondary central and western Kansas. layers after being buried under other recovery operations. Gases, steam, or Rangely oil field—An oil field in sediment. chemicals are injected through a Class northwestern Colorado where the U.S. Secondary oil recovery—Production of II fluid-injection well into a producing Geological Survey experimented with residual oil and gas from fields whose formation to lower the viscosity of the adjusting fluid pressure in injection reservoir pressures have dropped remaining oil and allow it to flow to the wells between 1969 and 1973 to after initial, or primary, recovery producing wells. determine how changing injection rates using natural underground pressure Horizontal drilling—Drilling that starts could control seismicity. and pumping. Water or gas is injected out vertical then gradually turns in a Rocky Mountain Arsenal—Established into a Class II fluid-injection well to horizontal direction to extend a greater in WWII, the RMA north of Denver increase pressure and force oil and distance into a known oil-producing was used by the U.S. Army to develop gas to the surface through production zone. chemical weapons and was later used wells. Hydraulic fracturing—Injection of to produce agricultural chemicals. A Seismometer—Instrument used to fluids and sand into a well to fracture deep injection well drilled there in 1961 measure ground motion and seismic oil-bearing rock layers. Colloquially for the disposal of hazardous chemicals waves generated by earthquakes and called “fracking,” especially when was abandoned in 1966 after 13 other seismic sources. used in conjunction with horizontal earthquakes of M 4 or larger occurred. Tectonic plates—Massive, rigid plates in drilling, hydraulic fracturing increases Earthquake activity declined but the lithosphere—Earth’s outer shell— permeability in rocks to free trapped oil. continued for two decades (Ellsworth, that are propelled from below by Mississippian limestone play—A 2013). molten rock and that interact with one complex group of oil and gas Sedimentary rocks—Rocks formed from another along their boundaries, which reservoirs within a shared geologic and sediment, broken rocks, or organic can cause seismic activity.

The mission of the Kansas Geological Survey, operated by the University of Public Information Circular 36 Kansas in connection with its research and service program, is to conduct April 2014 geological studies and research and to collect, correlate, preserve, and disseminate information leading to a better understanding of the geology Kansas Geological Survey Geology Extension of Kansas, with special emphasis on natural resources of economic value, The University of Kansas water quality and quantity, and geologic hazards. 1930 Constant Avenue Lawrence, KS 66047-3724 The Geology Extension program furthers the mission of the KGS by 785-864-3965 developing materials, projects, and services that communicate information http://www.kgs.ku.edu about the geology of Kansas, the state’s earth resources, and the products of the Kansas Geological Survey.

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