** Register Early!! Online Event Registration will close by 10:00 am on the day of the event.**
Join us Friday, September 11, 2026
as Mr. Scott Ausbrooks,
State Geologist of Arkansas
presents
Induced Seismicity in Arkansas: Overview of History, Case Studies, and Regulatory Response
with additional Focus on South Arkansas and Northern Louisiana
Abstract
Induced seismicity refers to earthquakes and tremors that are caused by human activity that alters the stresses and strains on Earth's crust. It is typically of a low magnitude. Induced seismicity is associated with industrial processes including geothermal, energy extraction, mining, dam building, construction, waste-water disposal, and hydraulic fracturing.
Arkansas has seen its share of earthquakes, both natural and human related. There are two areas in the state where seismic activity has been linked to the injection of produced fluids into large volume salt-water disposal wells (SWDs).
From December 1983 to September 1989 twelve small earthquakes were recorded for the El Dorado, Arkansas area. Magnitudes of these earthquakes were well below damaging levels. Prior to this time no seismicity was reported in the area, suggesting that the earthquakes were not naturally occurring and may have been the result of human activity. El Dorado is located at the margin of a region of underground waste brine disposal and along a major fault zone. Elevated pore pressures resulting from brine disposal may have reduced the normal (locking) stresses across fault surfaces and triggered fault movement. Two injection wells in the El Dorado South field are in close proximity to fault surfaces at the depth of injection. The two wells also lie at the center of the macro-seismic area and show increases in injection rates prior to periods of seismicity. These relationships suggest that pressured fluid injection triggers earthquakes in the area.
Between 2008 and 2015, the natural gas industry actively developed the Fayetteville Shale in north-central Arkansas which included drilling nearly 6,000 production wells. After the first saltwater disposal (SWD) wells associated with the development of the Fayetteville Shale became operational in April 2009, central Arkansas experienced an increase in the rate of earthquakes with M<4.7. This seismic activity in the Fayetteville Shale development area (FSDA) included both natural and induced earthquakes that often occurred in spatial and temporal clusters. The Center for Earthquake Research and Information and the Arkansas Geological Survey closely monitored the area using a permanent network of seismograph stations augmented by portable real-time, broad-band stations, to focus on specific sites of suspected induced seismicity. We communicated any concerns directly to the Arkansas Oil and Gas Commission (AOGC), the agency charged with regulating SWD wells in the state. AOGC response included reduction in injection rates, volumes, well shut-ins, and a moratorium in the FSDA.
Biography
Scott M. Ausbrooks is the State Geologist of Arkansas and serves as Director of the Office of the State Geologist (OSG). He is a registered professional geologist and has been employed with the OSG for over 20 years. He has earned two Bachelor of Science degrees in Geology and Surveying from the University of Arkansas at Little Rock and a Master of Science degree in Earth Science (Geophysics) from the University of Memphis. Mr. Ausbrooks was project leader overseeing the installation of the Arkansas Seismic Network, which consists of nine-state-of-the-art permanent broadband seismic stations across Arkansas between 2009-10. He was a co-investigator of the study that determined the relationship of nearby saltwater disposal wells and the Guy-Greenbrier earthquake swarm that occurred between 2010-11. More recent work includes research into potentially human-induced earthquakes related to hydraulic fracturing in the Fayetteville Shale Development Area in north-central Arkansas. Other experience includes geologic mapping; quality control sampling for quarries; preparation of geological reports for bridge replacement projects; landslide studies; drill core inspections; monitor well driller; technical writing; geotechnical logging; surveying; and environmental consulting.
** Remember to Register Early!! Online Event Registration will close by 10:00 am on the day of the event in order to get the online details out in a timely manner. In-person registration available until the meeting starts.