(Bloomberg) — A 5.4-magnitude earthquake rocked a key oil-producing region in West Texas, rattling parts of the Permian basin.

The quake struck 22 kilometers (13.6 miles) northwest of Midland at 5:35 p.m. local time on Dec. 16, according to the US Geological Survey. No injuries have been reported.

It’s the second time the West Texas region has been hit by an earthquake in the past month. On Nov. 16, a quake hit near Mentone, which at the time was put at a 5.3-magnitude event.

The Permian — the largest oil-producing region in the US — sees more fracking than anywhere in the world. The practice uses water pumped into wells at high pressure to release hydrocarbons from the shale rock.