Topeka ? Geologists on Tuesday told a Kansas House committee that more seismic monitoring in the state could help determine if hydraulic fracturing, or fracking, is connected to earthquakes.

Rex Buchanan, interim director of the Kansas Geological Survey, testified before the House Energy and Environment Committee that no evidence exists that the fracturing of rocks deep beneath the earth’s surface was producing earthquakes that can be felt.

“It is always difficult to know what is a natural and what is a man-made event,” Buchanan said.

Kansas has seen an increase in oil and gas exploration in southern counties as new technology allows extraction in difficult geological formations. Hydraulic fracturing involves high-pressure injections of liquid into underground rock to release trapped fossil fuels.

Fracking has been suspected as a cause of increased seismic activity in parts of the U.S. that typically aren’t prone to earthquakes.

Legislators heard the testimony for information purposes. There is no pending legislation that would further regulate fracking. A working group of officials with the Kansas Corporation Commission, KGS and the Kansas Department of Health and Environment is developing a draft plan of response to possible causes of increased seismic activity.

The increased oil and gas activities are in a geological region known as the Nemaha Ridge, which runs from Marshall County in north-central Kansas through Cowley County in the south. It is a buried granite ridge associated with the Humboldt Fault Zone. No faults that have produced earthquakes in the state are at the surface.

Buchanan said the largest quake in recorded Kansas history was in 1867 when a 5.5 one near Wamego, which was felt as far away as Dubuque, Iowa.

It is believed that most of the seismic activity related to fracking is caused by the injection of wastewater used in the process that is injected back into rock formations. The waste, primarily saltwater and other chemicals used in the fracking process, causes what is called “induced seismicity” where the liquid causes friction between faults or rock formations to ease and the geology to slip.

Buchanan said most of these earthquakes are small in scale, but without adequate monitoring to assess what is a normal level of seismic activity it is difficult to know how much fracking is contributing to activity.

Kansas has two U.S. Geological Survey monitors, one near Cedar Bluff and a second near Manhattan that’s currently inoperable. The Oklahoma Geological Survey operates equipment that can detect activity in southern Kansas on a limited scale.

Rick Miller, a senior KGS scientist and geophysicist, said it would cost about $200,000 to install equipment in southern Kansas and an additional $100,000 in ongoing expenses to monitor and analyze seismic activity to establish baseline data.