"Then another tremor comes a second later, like a truck passing nearby," said the 44-year-old, who did not wish to disclose his last name.

Echoing his words, three quakes rocked the ground in just one day on February 4.

This region of the Permian Basin, from which 40 percent of US oil and 15 percent of its gas are extracted, experienced nine earthquakes greater than three-magnitude in 2019, 51 in 2020 and 176 in 2021, according to market intelligence firm Sourcenergy.

What causes earthquakes is not fracking itself, but injecting the wastewater into wells. The Railroad Commission of Texas, which regulates oil activities, has had to impose new rules on water disposal.

- 'Fox guarding the henhouse' -

Drilling companies must deal with huge quantities of water that come up when fracking -- water makes up about 80 percent of the fluid pumped out of the ground.

Almost 4,000 active wells have been drilled specifically to collect the wastewater in the Permian Basin.

"As you get more and more water getting pumped into the ground... you're filling up these spaces," said Joshua Adler, CEO of Sourcenergy, which helps oil companies improve water management.

"In some of these spaces, you got these cracks or fault lines. You're pushing it harder and harder, and maybe you hit that fault line and maybe it makes it slip and that's an earthquake."