Previously undiscovered faults deep underneath Oklahoma could be causing a spike in earthquakes in the state. Using magnetic imaging to peer into the deepest depths below the Earth's surface, scientists found the fault lines while studying an area where four large tremors have hit since 2011.
Per an ABC News report, the new faults appear to be extensions of previously known faults. By examining the structure and "grain" of the rock below Oklahoma, scientists with the Oklahoma Geological Survey and the U.S. Geological Survey noticed different minerals next to each other. This side-by-side difference in material indicates a potential fault line as some of the rock must have moved.
"In Oklahoma, there is a grain (similar to wood grain) to the deep rocks, and it is aligned in a way for the stresses to generate a 'slip,'" said the study's lead author Anji Shah.
Before 2009, Oklahoma only experienced one magnitude 3.0 earthquake a year. By 2015, the number increased substantially to 903. So far this year, 80 similar magnitude quakes have been recorded by seismographs.
The most recent earthquake struck north-central Oklahoma yesterday, according to a report from the San Francisco Chronicle. The 3.5-magnitude tremor was recorded by the USGS near Pond Creek, a small community roughly 85 miles from Oklahoma City. Fortunately, the quake did not cause any injuries or significant damage to buildings.
Experts believe wastewater injection, a process used by oil and gas companies to dispose of wastewater, is triggering the movement of the newly discovered faults. As a result, the Oklahoma Corporation Commission's Oil and Gas Conservation Division has ordered the closure of several injection wells and a reduction in operations for many others.
Scientists with the Oklahoma Corporation Commission are very interested in the new study.
"I hope we learn even more from this," said commission spokesman Jim Palmer. "The hope is to make sense of what the data is telling us. Anything we can do to reduce the number of earthquakes in Oklahoma is what we want."
The Oklahoma Geological Survey and USGS are planning a more in-depth study of the area where the new faults were discovered. Any additional data will help scientists determine the likelihood of continued earthquakes in the area and help with preparations before the next one comes.