The central United States saw a rise in seismic activity last year, seismologists said Monday.

Kansas, Oklahoma and Texas combined to witness 32 earthquakes of at least magnitude 4.0 in 2015, the United States Geological Survey (USGS) said in a news release announcing last year’s global earthquake totals, nearly doubling the 17 quakes of that size that hit those states in 2014.

The news will hardly surprise residents of Oklahoma, which has seen a dramatic rise in quake frequency and magnitude since 2009. Officials have linked the surge to wastewater from oil and gas companies operating in the state, and regulators have taken steps to reduce its production.

Globally, however, the USGS said last year’s quake totals were “on par with prior year averages.”

The world usually sees about 14,500 earthquakes of magnitude 4.0 or greater and 18 earthquakes of magnitude 7.0 or greater every year, according to the USGS. Last year, those totals were 14,588 and 19, respectively, though the numbers may change pending a final review.

While earthquake totals might not have increased, the USGS reported they were far deadlier.

The organization said earthquakes killed 9,612 people last year, up from the 2014 total of 664.

Nearly 9,200 of them were killed in magnitude 7.8 and 7.3 earthquakes that hit Nepal in April and May, the USGS said. The first and more powerful quake on April 25 killed 8,964 people, and 218 died in the May 12 quake. Another 430 died in quakes in Afghanistan, Malaysia and Chile.

While Kansas, Oklahoma and Texas saw some powerful earthquakes, they didn’t see the most powerful one to hit the United States last year. A magnitude 6.9 earthquake off the coast of Alaska’s remote Unmak Island in July holds that distinction, according to the USGS.

However, Oklahoma’s trend of increased activity appears to be carrying over into the New Year.

The state has already seen seven earthquakes of magnitude 4.0 or greater in 2016, USGS data indicates. This year’s quakes include a Jan. 6 magnitude 4.8 earthquake near Fairview that is one of the strongest in the state’s history, according to Oklahoma Geological Survey records.

Oklahoma experienced just 21 earthquakes of magnitude 4.0 or greater in a 64-month stretch from January 2009 to May 2014, the USGS said in a news release at the time. That included a magnitude 5.6 quake that hit near Prague in November 2011, the state’s strongest on record.

Both the USGS and Oklahoma Geological Survey have cautioned the rise in Oklahoma’s earthquake activity increases the risk that the state could see an even bigger quake.

Oklahoma isn’t the only state where earthquakes pose a risk to the public.

The USGS reported last August that about 143 million people in the continental United States live in areas where they could be exposed to potentially damaging earthquake tremors. That was nearly double its previous estimate of 75 million people, published in 2006. The organization said the rise was the result of population shifts and a better understanding of seismic activity.

California, Washington, Utah, Tennessee, Oregon, South Carolina, Nevada, Arkansas, Missouri and Illinois are the states with the most people exposed to potentially damaging shaking, the USGS said.