Experts seek cause behind increase of earthquakes

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OKLAHOMA CITY- With a dramatic increase of earthquakes over the past few years in the central and eastern United States, experts were left to wonder if they could be linked to human activity.

A recent study by the U.S. Geological Survey said there’s a possibility humans are playing a role in the quakes. Since 2009, Oklahoma has seen a dramatic increase in the number of earthquakes.

The Oklahoma Geological Survey, based out of the University of Oklahoma, says it can track a few of these underground land movements each day. Many people are wondering what is contributing to the sudden increase.

However, experts say it's a challenge to find any specific answers.

Austin Holland, a research seismologist with the Oklahoma Geological Survey, said,"Trying to decide what's natural versus somehow caused by man can be a very difficult thing."

Officials say one possibility is an injection-induced earthquake, which focuses on fluids going into deep wells as a way to dispose of waste water. In Oklahoma alone, there are nearly 10,000 injection wells across the state.

There is also hydraulic fracturing, or "fracking," being listed as another cause of the recent spike in earthquakes.

Holland says, "It looks like about, up to 10 percent of the recent earthquakes could be attributed to hydraulic fracturing."

However, most of those earthquakes are less than a magnitude zero, meaning they go unnoticed.

Then, there's waste water disposal. In Oklahoma, most of the water disposed is what's called "produced water."

"Produced water" comes out with the oil and gas and is usually salty and not drinkable.

This water is disposed into deeper zones within the Earth. However, there are specific rules that need to be followed to prevent drinking water contamination.

Holland said, "There are a lot of regulations in place regarding these wells through the EPA and states, as well to protect our drinking water quality."

The cause of more earthquakes might be unknown right now but there's plenty of research being done on the local and national level to keep up with land movements.

Holland said, "Our historical seismicity is now this changing thing we don't know how to address in current seismic hazard assessment."

There are 14 seismic stations around Oklahoma that track earthquake activity. The Oklahoma Geological Survey hopes to double that number by the end of the year.