Shock after shock
Updated On: Jul 29 2014 07:50:24 AM CDT
When you think of earthquakes, you probably think of California. A place known for tremors that topple buildings, crack highways and overturn cars.
How about Harper County, KS? In just the first three months of 2014, at least 24 earthquakes have been recorded in that county alone with magnitudes from 1.3 to 3.7.
“Thinking about somebody who has never felt earthquakes, suddenly starting to feel a few a week? I think that would be a big surprise to me,” said Justin Rubinstein, with the US Geological Survey based out of California. He said he couldn't believe he was going out to Kansas in regards to earthquakes. Tornadoes, yes. Earthquakes, not so much.
Rubinstein and his team are doing more research in Kansas and Oklahoma after the sudden increase in seismic activity.
“About a month ago we put out five seismometers in Harper and Sumner Counties to start recording the earthquakes so we can understand what’s going on,” said Rubinstein. “We have plans to put out another 4 seismometers in the next month or so, followed up by another 6 seismometers in the next 4-6 months.”
South-central Kansas has recorded at 57 earthquakes since August 2013, according to data collected by the Kansas Geological Survey.
"The question really is, is this related to oil and gas activities here and that's certainly something that's open to debate,” he said.
To better understand the situation in Kansas, we look to our neighbors to the south, where seimologists say they have linked human activity to some seismic tremors. In 2013, Oklahoma set a record with 109 earthquakes, 3.0 magnitude and above. This year has already broken that record, with 138 3.0 or greater earthquakes, according to data gathered by the Oklahoma Geological Survey and the US Geological Survey.
"Certainly some of the earthquakes in Oklahoma have been seen to be related to waste water injection there and that's a possibility here," said Rubinstein.
Waste water injection is the process used by oil and gas companies to get rid of large volumes of salt water they collect during the hydraulic fracturing or fracing process. The US Geological Survey said the process of fracing itself isn’t likely to cause an earthquake.
“It’s far more likely that induced earthquakes are going to be coming from waste water injecting than fracing,” said Rubinstein. “But again this is only going to be happening in areas that you have faults, and ones that have enough stress that they could actually slip.”
Waste water injection means digging a well thousands of feet below the Earth’s surface to release salt water into porous rock. In south-central Kansas, petroleum geologists say that is usually the Arbuckle Formation which is down roughly 5,000 feet. Across the state of Kansas, there are 16,000 such wells according to the Kansas Corporation Commission.
"In Kansas we've been disposing of salt water for 40, 50, 60 years,” said Rex Buchanan, Interim director of the Kansas Geological Survey. “So why now think salt water might be causing induced seismicity? Well with some of the activity we’ve seen, especially in Oklahoma, you’ve seen larger volumes of water then we’ve historically seen and some of these horizontal wells are extremely productive in terms of salt water. In some locations we are putting more salt water back into the ground even from 10 years ago. So that’s one possible explanation, but again the jury’s still out. “
Buchanan was chosen by Governor Brownback to lead the Induced Seismicity State Task Force. Their goal is to come up with an action plan if the increase in Earthquakes is found to be caused by human activity.
“We’ve got folks modeling a geological map of the subsurface to take a look at disposal in the area of some of these earthquakes and get a better hand on where these earthquakes occur along the lines of depth,” said Buchanan.
According to geologists in the state, in order for waste water injection to cause an earthquake, the fault would need to cross the same depth as where the water is being released.
“It's kind of greasing it,” said Petroleum Geologist Doug Davis. “Putting fluid into that break and allowing it to move easier."
Davis said unlike mountainous regions, most of the known faults in Kansas are thousands of feet deeper than the injection wells, but the USGS said it is faults we don’t know about that are causing issues now.
“We need to know more about the geology about Kansas,” said Rubinstein of the USGS. “Many of these faults are really hidden in the unknown. A lot of the areas where we are seeing the seismicity are on faults we didn’t know about.”
"Maybe there's a circumstance where we need to do seismic in certain areas to see, are there faults around here we are not aware of?” Davis said. “Maybe we shouldn't dispose in this region. And that might be a way to stop some of this. I don't know."
Although Davis said he believes the earthquakes are more than likely natural, he said research needs to be done to know for sure. He said geologists still have a lot to learn about earthquakes, but the more they study the better off everyone will be.
"It's taken 60 years to get Doppler in all the places in the US so we can understand and better help keep people safe from tornados,” he said. “We're doing the same thing with earthquakes. How long is it going to take? We don't know. The more we study it the better we’re going to be. Maybe we’ll figure it out. We want to figure it out.”