USGS links Oklahoma’s 5.1M (third largest) earthquake to oil-field disposal wells more than 7 miles away

USGS links 5.1 quake to distant oil-field disposal wells by Mike Soraghan, October 25, 2016, E&E News

Scientists have linked one of Oklahoma’s largest recorded earthquakes to oil-field disposal wells more than 7 miles away.

Scientists at the U.S. Geological Survey studied a magnitude 5.1 quake in February in western Oklahoma and linked it to the relatively distant wells. They noted that there was little shaking closer to the wells.

“The fact that seismicity is rather limited near the high-rate wells while the Fairview sequence occurred at a relatively larger distance from these wells, shows us the critical role pre-existing, though possibly unknown, fault structures play in inducing large events,” said William Yeck, a USGS scientist and lead author of the study.

The study, available in the online edition of Geophysical Research Letters, noted that disposal volumes had risen sevenfold in the previous three years.

At the time, the quake near Fairview, Okla., was considered the second largest recorded quake in the state’s history after a magnitude 5.7 event in 2011 near Prague. A magnitude 5.8 quake in September near Pawnee is now considered to be the largest quake recorded in the state.

The Fairview quake was reportedly felt across Arkansas, Iowa, Kansas, Missouri, Nebraska, New Mexico and Texas (Greenwire, Feb. 15).

Scientists and state officials have tied a massive increase in the number of earthquakes in the state to wastewater disposal wells from oil and gas production.

Researchers say favorably aligned faults have combined with Oklahoma production methods that result in unusually large volumes of wastewater to create swarms of earthquakes.

Last year, Oklahoma had 903 earthquakes of magnitude 3 or greater, a sharp increase over the 585 such quakes in 2014. Before 2009, the state averaged about two such quakes a year. [Emphasis added]

5.1 earthquake likely caused by wastewater disposal: U.S. Geological Survey by Canadian Underwriter, October 24, 2016
The third-largest earthquake in Oklahoma was likely triggered by underground disposal of wastewater from oil and natural gas production, the U.S. Geological Survey found in a report issued Monday.

The magnitude 5.1 quake that struck northwest of Fairview in February was likely induced by distant disposal wells, the agency said. The USGS report indicated that in the area around where the Fairview quake occurred, the volume of fluid injected had increased sevenfold over three years.

The Fairview temblor had been the largest in the central and eastern U.S. since a magnitude 5.7 quake hit near Prague in 2011. In September, the largest earthquake in the state struck near Pawnee with a magnitude 5.8. The relationship between that quake and wastewater injection is still being studied.

A study by the U.S. Geological Survey last year suggested that the sharp rise in earthquakes in Oklahoma in the past 100 years had likely been the result of industrial activities in the energy-rich state, such as oil and natural gas production. [Emphasis added]

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