The number of earthquakes related to fracking has fallen significantly in Oklahoma since last year, leading government experts to attribute the decline to increased regulation.

The state's rate of earthquakes was at times higher than that of California, which is considered the U.S. epicenter for naturally occurring earthquakes.

The U.S. Geological Survey told USA Today that the reduction in earthquakes in the oil and gas state is mostly likely due to new regulations put in place to reduce the quakes' frequency.

The state is still experiencing a whopping number of earthquakes after the regulations were put into place. It has had 448 earthquakes of a 3.0 magnitude or higher this year. But that's down nearly 20 percent from last year, when the state experienced 558 quakes in the same period, according to the U.S. Geological Survey.

The practice of hydraulic fracturing, or fracking, is not the culprit in causing the earthquakes. Fracking refers to a process where sand and water are injected at great depths underground to loosen oil and gas from shale rock formations. The process has made the U.S. the leading oil and gas producer in the world.

Instead, the quakes are associated with the disposal of the water used in the fracking process, which requires injecting the wastewater into underground aquifers.

The state has established a number of new regulations to control the rate of water injected into underground aquifers, which has been the proven cause of quakes not only in Oklahoma but also in places as far away as Ohio.

Robert Williams, a geophysicist with the U.S. Geological Survey, said increased regulation of wastewater underground disposal related to oil and gas production could be one reason for the decline in earthquakes.

At the same time, oil production has slowed, which means there is less water to dispose of from fracking wells, he said. The lower production is due to the global supply glut, where the oversupply of crude oil on the worldwide market has cut prices so low that it is not economical to drill.