The first occurred just before 3:30 a.m.
The second, slightly stronger at a 3.3 magnitude, took place a few minutes before 6 a.m.
The rumbles were centered about a mile northeast of Greenbrier.
They started about a mile underground.
There are no reports of damage, according to the Faulkner County Sheriff's Office.
To keep up with the rumblers, check out the U.S. Geological Survey.