Pat McKinney’s science class at Jackson Heights Middle School has a firsthand look at earthquake activity that puts southern Kansas and central Oklahoma on par with California.

McKinney has a small seismograph that registers earthquakes all over the world, from Asia to South America and even close to home, in her classroom north of Holton. Over the weekend and on Monday, two earthquakes under magnitude 3.0 shook a small area near Caldwell, located south of Wichita. Her seismograph didn’t register the temblors, likely because of a power failure, but when oil and gas producers curbed the amount of saltwater injected into the earth last year, her class saw a sharp drop in earthquakes in southern Kansas and Oklahoma.

"It was almost immediate," she said. "We still see them, but there’s not nearly as many."

Despite the decrease, those man-made earthquakes make the region — an area encompassing nearly 3 million people — just as prone to earthquake damage as California, according to an updated earthquake outlook from the United States Geological Survey, and the area will continue to be active in 2017.

"The forecast for induced and natural earthquakes in 2017 is hundreds of times higher than before induced seismicity rates rapidly increased around 2008," USGS scientist Mark Petersen said in a statement. "Millions still face a significant chance of experiencing damaging earthquakes."

Last year, the strongest earthquake on record in Oklahoma, a magnitude 5.8, rocked an area near Pawnee on Sept. 3. Just over a month later, a 5.0 magnitude quake struck 25 miles south of Pawnee, near Cushing, a central oil town calling itself the "Pipeline Crossroads of the World."

Those earthquakes are part of a larger trend. From 1980 to 2000, Oklahoma averaged about two earthquakes a year with a magnitude 2.7 or greater. That number jumped to about 2,500 in 2014 and escalated to 4,000 in 2015 before falling back to 2,500 last year.

Kansas has been less active but still saw a sharp uptick during the same time frame, said Rick Miller, a senior scientist at the Kansas Geological Survey.

The vast majority of quakes in Kansas are below magnitude 2.0, but in 2014 the state recorded about 130 at that level or higher and about 160 in 2015. In 2016, after the industry curbed injections, the number of magnitude 2.0 earthquakes fell below 100. That is compared to about 20 in 2013, according to Kansas Geological Survey data.

The Humboldt Fault, which runs from Iowa south through Kansas and into Oklahoma, makes the area seismically active. Historically the area is capable of producing earthquakes, but human-induced earthquakes are what makes the area as prone to temblors as California, according to the USGS study.

Hydraulic fracturing, commonly referred to as fracking, is sometimes blamed for induced earthquakes, but the USGS points to wastewater disposal as the primary cause in many locations. Wastewater from oil and gas production is disposed of by injecting it into underground wells. Injection of the fluids causes pressure changes that can weaken a stressed fault and bring it closer to failure, Miller said.

"There’s absolutely no question whatsoever from the science that’s out there that deep injection induces earthquakes," he said.

The USGS outlook focused on earthquakes at or above magnitude 2.7, but Susan Hoover, a USGS geophysicist based in Golden, Colo., said earthquakes at magnitude 4.0 and higher can cause damage.

This is the second year USGS has produced a one-year outlook that focuses on both induced and naturally occurring earthquakes. In past years, surveys have looked at earthquake hazards across the country but intentionally ignored induced earthquakes, Hoover said. Until recently, most induced earthquakes were too small to assess or were caused by operations that had ended. The sharp uptick in induced earthquakes in 2014 led to the USGS working with local geological surveys and others to track the phenomenon, Hoover said.

When it comes to feeling quakes, Miller said, something around magnitude 3.0, such as those that occurred in Caldwell, would likely only be felt for a few miles. Earthquakes magnitude 4.0 or higher can be felt for several hundred miles.

"It all depends on the ground under your feet," he said.

Regulators in both Oklahoma and Kansas have asked oil and gas producers to close or reduce injection wells. Last year, the Kansas Corporation Commission limited saltwater injection to 25,000 barrels a day in most areas and to as little as 8,000 barrels a day in the seismically active areas of Sumner and Harper counties.

Miller and the USGS have said those regulations, along with the decline of oil and gas extraction because of falling prices, likely led directly to the drop in earthquakes last year.

The seismograph at McKinney’s school has helped her teach the cause and effect humans have on the planet.

"We talk a lot about (it) and some of the things we do to the earth," she said.

Contact reporter Luke Ranker at (785) 295-1270 or @lrankerNEWS on Twitter. Like him on Facebook at facebook.com/lukeranker.