GUTHRIE, Okla. — The shaking came in the dead of the night on a recent Wednesday morning, vibrations so intense that they startled Faye Sayre out of a deep sleep. Her bed was lurching up and down and back and forth — and Sayre, in her drowsiness, initially thought it was Gunner, her 180-pound English mastiff puppy, leaping on her mattress as if it were a doggie trampoline.

“I thought, ‘Why is my dog jumping in my bed?’” Sayre recalled. “The bed was really rocking. ... And she doesn’t do that. She’s not excitable like that. She’s a very calm dog.”

But as Sayre sat up to figure out what was happening, she noticed Gunner was sprawled in her usual spot on the floor next to her bed. The dog was looking up at her quizzically, and Sayre suddenly realized it wasn’t just her bed that was moving. The entire room was shaking.

“Here we go again,” Sayre thought.

It was an earthquake — one of the more than 150 quakes measured at magnitudes of 2.5 or higher on the Richter scale that have hit Oklahoma in the last month alone.

While most of the quakes have been small compared to the tremors that regularly rock California and other earthquake-prone states, the recent burst of seismic activity has made Oklahoma one of the shakiest states in the country, according to the U.S. Geological Survey.

And that’s weird in a state better known for its wild springtime weather and where most people, until recently, had never even felt an earthquake, much less considered how to react to one.

Oklahoma is still rebuilding from two of the strongest tornadoes ever recorded, which swept a deadly path through the central part of the state last May. Storms are such a way of life here that people are raised from an early age to cast a wary eye toward the sky. They are experts on all things meteorology — from the telling “hook echo” clouds that precede tornadoes to the way the air feels before a big storm is about to hit — because they’ve had to be.

But earthquakes? Not so much — at least not until recently. Now local libraries have been inundated with requests for books about earthquakes, and residents on shaky ground have loaded their Netflix queues with documentaries about a natural phenomenon that is even more unpredictable than tornadoes — all while wondering if the small quakes rumbling the plains mean Oklahoma is on the brink of “the big one.”

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“A few years ago, people would have said you’re crazy to talk about earthquakes,” said David Ball, emergency manager for Logan County and the city of Guthrie, a small town just north of Oklahoma City that has been the epicenter for much of the state’s recent seismic shifts. “They are so regular now that it’s like, ‘Did we just have an earthquake or is that the wind blowing?’”

Two weeks ago, on Apr. 10, 16 earthquakes hit Oklahoma in a single day, including a magnitude-4.1 earthquake centered near Guthrie. Dozens of aftershocks have continued to rattle the state since then, including two magnitude-4.0 earthquakes last weekend. One struck Edmond, a suburb of Oklahoma City, raising concerns that the quakes could be inching closer to more populated areas of the state.

Scientists are still at a loss to explain exactly what is causing the ground to shake with such frequency and what appears to be a growing intensity — a major concern for a state where few buildings have been constructed to withstand even minor earthquakes.

Some question whether the earthquakes have been triggered by oil and gas drilling. Others wonder whether the shaking of the earth is a divine providence foreshadowing the apocalyptic end of the world as prophesized in the Bible. But scientists say they just have no idea.

“It’s very mysterious what’s going on,” said G. Randy Keller, director of the Oklahoma Geological Survey, which tracks and studies seismic activity in the state. “We are trying to figure it out, but right now, we just don’t know, and it’s concerning to us.”

And it’s perhaps most concerning to people in Guthrie, one of the oldest cities in Oklahoma with blocks and blocks of old Victorian buildings that residents fear could be particularly vulnerable if a big quake were to hit. The town, perhaps best known outside of Oklahoma for its cameo role in the film “Rain Man,” is home to dozens of antiques shops full of old china and glassware that shake and rattle with each tremor.

“They happen so often now, it doesn’t really bother me as much as it did before,” said Sayre, who works at one of those antiques shops. “But honestly, what worries me is if a big one really did hit, what would we do? I don’t think anybody really knows what to do.”

At a time when Oklahomans are bracing for what are traditionally the most active weeks of spring storm season, the earthquakes are the talk of Guthrie — in the shops, at the drugstore and in the church pews — almost more than possibility of tornadoes. And that’s saying a lot for a state populated by obsessed weather junkies.

“When we first started having them, most people I talked to viewed them as exotic, and they would say, ‘Oh, I can’t wait to feel one,’” Ball said. “But now, they happen so often that people are starting to get annoyed. ... 'Why us? Why is this happening to us?’”

Before 2010, Oklahoma averaged about two to three “felt” earthquakes a year — meaning they were strong enough to rattle dishes or shake things off the wall. Many occurred in remote western parts of the state near the Meers Fault — a 15-mile jagged crack in the earth near Lawton, Okla., that is actually visible from the air.

Until a few years ago, people here had only heard rumors about earthquakes in Oklahoma passed down through generations — though there wasn’t much to say. Even those who were alive barely remember a magnitude-5.5 quake in 1952 near Oklahoma City that left behind cracks in the state Capitol building. Until a few years ago, it was the biggest recorded earthquake to ever hit the state, but it was rarely, if ever, discussed.

But the state’s awareness of quakes has changed within the past five years as seismic activity has dramatically ramped up. According to the OGS, there have been 40 times more earthquakes since 2009 than in the previous 30 years — many centered near a series of old fault lines that run north to south in Central Oklahoma.

In 2011, a magnitude-5.6 earthquake struck near Prague, about an hour east of Oklahoma City, causing parts of a state highway to buckle and significant damage to homes near the epicenter. Since then, activity has only continued to increase, with the state setting new records each year for seismic activity.

Just four months into 2014, Oklahoma has already set a new record for earthquakes. So far this year, according to the OGS, there have been more than 140 earthquakes registering at a magnitude of 3.0 or above, compared to 109 for the entire year of 2013. In 2012, there were just 40 earthquakes that registered at a magnitude of 3.0 or above.

The sudden jump in activity has attracted interest from geologists across the country — even from California — who have descended on Oklahoma to try and understand what’s causing the earthquakes.

One source of suspicion and debate has centered on the state’s booming natural gas industry, which has increased its production using a technique known as fracturing — or fracking. The process uses large amounts of water to coax gas from underground rock formations, and some scientists have speculated the disposal of that wastewater in deep-injection wells near the fault lines could be triggering earthquakes.

Earlier this month, geologists in Ohio linked earthquakes there to fracking, and authorities in Texas, where quakes have also been on the increase, are investigating that source as well.

Last month, a USGS study concluded that wastewater injection might have triggered the 2011 earthquake near Prague, Okla., by creating a manmade earthquake the day before that in turn triggered the magnitude-5.6 natural earthquake. But while the OGS has acknowledged that activities related to oil and gas exploration could be a factor in the dramatic increase in quakes, scientists there argue more conclusive study needs to be done.

“We’re just not sure,” Keller said. “Geoscientists are a lot like MDs. We have fancy tools and graduate educations, but the patient is very complicated. ... We don’t just don’t know if what is happening is natural or if it’s caused by man. There’s evidence on both sides. And we don’t know why it’s happening now. It’s all very disquieting, and everybody wants to figure this out. But it needs more study.”

There are some signs Oklahoma officials are buying into the theory that oil and gas drilling could be playing a role. Last week, the state Corporation Commission passed a rule that would force drillers to report their wastewater injection rates on a daily basis instead of monthly to allow researchers to track in real time whether those activities are triggering earthquakes. (The measure has to be approved by the state Legislature and the governor.)

At the same time, the OGS has increased its number of seismic activity monitors around the state from seven to 30 — with several positioned near Guthrie, in hopes of learning more about why the ground is shaking so much.

This being the Bible Belt, there are people who have wondered if Oklahoma’s earthquakes aren’t some sign of the end times as prophesized in the book of Revelations.

It’s an idea that first made the rounds in 2011 after the Prague earthquake when televangelist Pat Robertson pointed to the quakes and urged people “to get right with the Lord.” And the theory has been revived again with the latest surge in quakes — though no one wanted to be quoted by name admitting they’ve entertained the idea that the ground shaking could be a sign of God’s wrath upon a sinful people.

Many locals here are dealing with their jitters the only way they really know how: by trying to have a sense of humor about the state’s incredible bad luck with Mother Nature in recent years.

In addition to the most dangerous tornadoes on record, Oklahoma has suffered through record drought, deadly fires, floods and even a locust plague a few years ago. Another favorite story among Oklahomans is how, in 2007, a weather system that had moved into the state from the Gulf of Mexico suddenly developed into a rare inland tropical storm just west of Oklahoma City, swirling in place just like a hurricane.

The prevailing attitude now is what could possibly come next?

“Hopefully we will never have a volcano here in Oklahoma,” Ball said. “But at this point, after all the weird stuff that has happened here, you never say never.”