Quake safety on the mind

November 18, 2011 Feature Print Print
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Oklahomans are still shaken by the earthquakes that hit the state earlier this month and some wonder if the ground is going to shake again.

Geology Professor Gary Houlette said while earthquakes will likely happen again, it’s unlikely the state will experience anything significantly stronger in the near future.

“I’m not sure if we have enough actual movement in Oklahoma to really worry about sevens or eights,” said Houlette, referring to the strength of an earthquake as measured by the Richter scale.

Oklahoma has experienced several earthquakes this month, including the record-breaking 5.6 magnitude earthquake on Nov. 5, a 4.7 magnitude earthquake that preceded it early that morning, and a 4.7 magnitude earthquake that followed the evening of Nov. 7.

 

OCCC’s campus hardly suffered any damage.

Monica Carlisle, the lead library circulation assistant, said a plaque indicating the location of maps and atlases fell off the wall and broke. She said the damage was assumed to have been caused by one of the earthquakes.

Residents in other parts of the state weren’t so lucky. Sheila Mazkoori, a News Writing student from Prague, OK, said her family’s home suffered significant damage from the earthquakes.

“I was at home for the first one,” she said, referring to the 4.7 magnitude quake that happened early Saturday morning, Nov. 5. “The first one did some damage, but the second one messed up our living room.”

Several photos of Mazkoori’s living room show long cracks spreading across the walls.

Mazkoori said her chimney fell during the 4.7 magnitude earthquake early Saturday morning.

According to the U.S. Geological Survey, the epicenter of the 5.6 earthquake was 5 miles northwest of Prague.

Locating the epicenter of an earthquake involves triangulating the position between seismic stations. “To locate the epicenter, you have to locate between at least three [stations],” Houlette said.

The Richter scale is the most common method of measuring earthquakes. Each whole number on the Richter scale represents 10 times more amplitude in seismic waves, and corresponds to about 31 times more energy being released than the whole number just below it.

Another scale, the Modified Mercalli Intensity Scale, measures an earthquake with observed damage.

Falling chimneys is one of the criteria on the Modified Mercalli scale, Houlette said.

The fall of a chimney is classified as an eight (VIII).

The Oklahoma Geological Survey’s website said the earthquake probably occurred on the Wilzetta fault line. The vast number of fault lines in that area makes it difficult to pinpoint exactly which fault was responsible for the quakes.

A map posted by the Oklahoma Geological Survey shows the Wilzetta fault east of Drumright, and extending southwest to near Shawnee.

While the recent earthquakes have been alarming, they may have reduced the risk for a larger quake in the same area.

“The longer we go without having a large earthquake, the more the stresses build up over time and the more potential we have for a larger earthquake,” Houlette said. “It’s like taking a two-liter bottle of pop and shaking it up. If you let the fizz out a little bit at a time, when you totally take the lid off it’s not nearly as bad.”

Houlette said before getting earthquake insurance, people should ask if their home will receive significant damage, and whether they can afford it.

The monthly cost of earthquake insurance depends on where you live. The deductible if your house receives damage is a percentage of your home’s value.

Not everyone can get earthquake insurance.

“We’re not eligible for it right now,” Mazkoori said. She said because her house is so close to where the quakes occurred, they have to wait before the house can be insured for future seismic events.

Many people are concerned that hydraulic fracturing may be causing tremors. Hydraulic fracturing, or fracking, is the process of pumping water into the earth to break apart rocks and reach oil.

“There are some questions about what that can do,” Houlette said. “I don’t think there’s any direct evidence that links hydraulic fracturing with the earthquakes that we’re having right now.”

A report from the Oklahoma Geological Survey stated it could not determine if fracking was responsible for a series of quakes in Garvin County that happened in January. It has not been ruled out as a possibility though.

Though earthquakes are novel and frightening to many, Houlette points out they’re part of the Earth’s geological cycle.

“Earthquakes are simply a release of energy within the interior of the Earth,” he said. “Our planet is constantly moving.”

For more information, contact Gary Houlette at ghoulette@occc.edu or visit the Oklahoma Geological Survey’s website at www.ogs.ou.edu.

To contact Mary Mcatee,
email onlineeditor@occc.edu.

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