How does waste water injection increase earthquake risk?

A:

Many oil and gas industry activities, including fracking, the underground injection of oil and gas wastewater, enhanced oil recovery, and fluid extraction, can induce earthquakes. Earthquakes induced by these activities are a particular concern for California because of our state’s high seismic activity and dense network of faults.  Studies in other regions have linked fracking to induced earthquakes in Ohio, Oklahoma, British Columbia and Alberta, including quakes ranging up to magnitude 4.6. Recent research indicates that fracking can induce larger earthquakes than previously expected.  The Arroyo Grande fault underlies Price Canyon oil field.