A month and a half after the Pawnee earthquake, experts said they're noticing something odd.
State leaders and energy experts met today in Tulsa for the annual Oklahoma Corporation Commission Oil and Gas Institute.
Friday afternoon there were three earthquakes in Northwestern Oklahoma, but experts said overall, the state is having fewer quakes than last year.
Last month's 5.8 magnitude earthquake near Pawnee is the largest in Oklahoma history, and it damaged several buildings and injured one man.
"The amount of damage was relatively moderate even given the size of that earthquake - we dodged a bullet there," said Jeremy Boak, Director of the Oklahoma Geological Survey.
Boak said the amount of damage isn't the only surprise.
He said it's "concerning" we haven't had any magnitude 4 or stronger aftershocks.
"It's worrisome," Boak said. "There's no guarantee you'll get one, but it makes you think this could be happening."
Boak said the 2011 5.6 earthquake in Prague and the 5.1 quake northwest of Fairview in February both had magnitude 4 or stronger aftershocks, leaving him and others wondering when the next big shakeup going to happen.
"Everyone I've talked to is kind of surprised we haven't had one," Boak said. "We've had some magnitude threes, but we're wondering why there's kind of a gap there."
But Boak said overall, earthquakes in the state are down this year.
"When we started this year, the rate was so high that I was concerned we were gonna have more than last year," Boak said.
Commissioner Todd Hiett said it's too early to know the impact of shutting down injection wells after the Pawnee quake, but he believes the Corporation Commission is going in the right direction.
"Most of what we've dealt with in the past year and a half has been north and west of there, the seismic activity is down over 50 percent year over year, so it gives us a good feeling that we are at least on the right track of addressing the issue," Hiett said.
There is some good news about the potential for a strong aftershock, experts said.
The OGS said we can't rule it out, but the probability declines each day.