TULSA, Okla. (AP) — Oklahoma's 4.0 earthquakes are up significantly this year, but the overall rate of earthquakes is declining.

Oklahoma has had six quakes of at least magnitude 4.0 halfway through this year, which is one more than all of last year. But the overall rate of earthquakes has declined, with 96 quakes of magnitude 3.0 or greater through June 30, compared with 144 at this point last year and 302 by the end of 2017, the Tulsa World reported. A magnitude 4.6 in April near Perry was the 12th largest in state history.

Scientists are largely seeing earthquakes on unmapped faults that we...