Before 2008, Oklahoma had barely any serious seismic activity. The state averaged one to two earthquakes of 3.0 or greater on the Richter Scale each year. This year, it’s seen 850 earthquakes of 3.0 or more, according to recent information released by the Oklahoma Geological Survey.

In seven years, Oklahoma has become the most seismic state in the country, dwarfing California for quake activity. And the cause seems pretty obvious: the disposal of water and chemicals used in oil and gas drilling. When disposal wells are dug too deep, say scientists, they break the fault line, causing the earth to writhe up.

Without serious regulatory restrictions on disposal wells, say critics, the problem keeps getting worse. There were 584 plus-3 earthquakes in 2014, and 109 in 2013.

The map here was generated by Dana Branham, a reporter with The Oklahoma Daily. This year’s earthquakes are in red, with bigger circles indicating bigger events.

Rivka Galchen had a great piece about Oklahoma’s earthquake phenomenon in the New Yorker earlier this year. She reported that earthquakes have become so common in the state that they’re now announced as part of TV weather reports or on billboards as you’re driving down the freeway.

This summer, the Oklahoma Corporation Commission asked drillers to reduce well depths in certain earthquake-prone zones and reduce the volume of water they’re putting down. But, judging by the increasing numbers of earthquakes, these restrictions aren’t having much effect yet.