Faced with a rapidly rising number of earthquakes, some of which have been brought into connection with fracking, the US state of Oklahoma is increasingly coming under geophysical scrutiny. Before 2008, reports say the state experienced one or two magnitude 4 earthquakes per decade, but in 2014 alone experienced 24.

Since the beginning of fracking activity in the state that has long been the site of conventional oil and gas exploration, the number of magnitude 3 earthquakes rose to 585 last year, more than any state except Alaska, and forecasts have raised the possibility of 1,100 such tremors during 2015.

A study by California’s Stanford University trying to get to the root of the problem has identified the triggering mechanism as disposal of salty waste water into Oklahoma’s Arbuckle formation, but said it believes the primary source is not flowback from fracking, but rather “produced water” that occurs naturally during the conventional drilling process.

In a decision nevertheless hailed by fracking opponents, the Oklahoma Supreme Court, addressing the issue for the first time, ruled this summer that homeowners who have suffered injuries or property damage through earthquakes, whether from fracking or conventional drilling, can sue for damages in state courts, thus thwarting efforts oil and gas exploration companies to block such lawsuits.