A review of earthquakes in Oklahoma in the past year shows their numbers are declining while the number of those quakes measuring 4.0 magnitude or greater are growing.
The review by the Tulsa World showed there were at least six quakes magnitude 4.0 or greater midway through 2018. In 2017, the largest was a 4.6 magnitude quake near Perry and it turned out to be the 12th largest in the known history of Oklahoma.
But the numbers also show that through June 30, there were only 96 quakes that measured magnitude 3.0 or greater. By midway 2017, there had been 144 such quakes and 302 by the end of the year.
Wastewater injection wells continue to be the focus of many scientists and others who blame them for the earthquake activity and resulting damages. The Tulsa World put the question to State seismologist Jake Walter….are the wells still driving the seismicity?
“So in some ways the wastewater injection has created a new paradigm that defies how we would categorize main shocks and aftershocks if this were a fault that had slipped in a more natural setting,” Walter said.
He noted that Oklahoma’s seismic risk appears to be in line with the latest hazard forecast put out by the U.S. Geological Survey in late March.
He also said just because the overall number of quakes has been reduced, there remains a strong probability of quakes 5.0 magnitude or greater.
“These 4s are definitely earthquakes that we’re hearing reports are causing damage. So these are serious events,” he told the paper.