HUTCHINSON, Kan. — Many questions are being asked about the rash of earthquakes that have hit the Hutchinson area over a five-day period.
The answers are basically the same as they were during a town hall meeting held last year with the Kansas Geological Survey. Deep disposal wells from oil drilling in southern Kansas and northern Oklahoma are thought to be causing the shaking here in Hutchinson. Justin Rubinstein with the U.S. Geological Survey (USGS) in San Francisco says they are seeing the same thing. “This pressure is migrating northward from the border area,” Rubinstein said. “The most plausible explanation is that these fluid pressures are rising and, for whatever reason, this particular area (southwest of Hutchinson) is more prone to have earthquakes.”
Although the disposal wells are roughly a mile deep, the pressure they are applying to the ground underneath may be causing the earth to shift. “What we expect is happening is there’s some fluid connection between this injection formation and the location where these earthquakes are occurring,” Rubinstein said. “And so that can be a system of fractures within the rock or, more likely, there is a fault and so the fluid pressure can go straight down to the location the earthquakes are occurring.”
The shaking with the quakes in the Hutchinson area is much quicker and violent than those occurring in southern Kansas and northern Oklahoma.
“When you’re really close to an earthquake, you feel the highest frequency. That’s why you have this very rapid shaking and ending very quickly,” Rubinstein added. “For these earthquakes you’re feeling from Harper and Sumner counties as well as further south in Oklahoma, those earthquakes are a lot further away and so those high frequencies start going away, but you still have the lower frequency, so it’s more of a rolling motion.”
During the town hall meeting last year, representatives from the Kansas Geological Survey couldn’t give an answer as to whether the quakes would continue and possibly get stronger. The area has now seen a half dozen quakes in the last week much stronger than in the past. Rubinstein says it’s really not known how the activity will play out in the future.
The USGS has deployed a network of 14 seismometers in the area to monitor seismicity. The USGS is actively collaborating with scientists and regulators at the Kansas Geological Survey, the Kansas Corporation Commission, the Kansas Department of Health and Environment, and the Oklahoma Geological Survey to understand the earthquakes.