Oil and gas regulators in British Columbia, Canada, confirmed this week that a 4.6-magnitude earthquake earlier this year was caused by fluid injection from hydraulic fracturing, also known as fracking.
The quake is the largest of its kind in the province to be linked to the process, whereby fluid in injected into the ground at high-pressure to release natural gas stored inside shale rocks.
Oklahoma’s energy regulator declared last month that the state now has more earthquakes than anywhere else in the world, which scientists have also linked to wastewater injections, a long-used method to dispose of the chemical-laced byproduct of oil and gas production.
A recent study by the U.S. Geological Survey traced wastewater injection methods to the 1920s in Oklahoma and tied the rise in quakes in the past 100 years to industrial activities, such as oil and natural gas production. About 1.5 billion barrels of wastewater was disposed underground in Oklahoma last year, according to statistics released by the governor’s office.