Geologist: History shows Oklahoma earthquakes not new phenomenon

By Jay F. Marks

Glen Brown is passionate about geology.

So passionate that he started poring over U.S. Geological Service earthquake data while he was on vacation in Florida six months ago.

Brown's studies yielded what he called some surprising information.

Brown, who is vice president of geology at Continental Resources Inc., said he discovered evidence that Oklahoma's rising number of earthquakes isn't as unprecedented as most people believe.

Brown found a similar earthquake outbreak in the 1950s, when Oklahoma did not have equipment to properly measure seismic activity.

He also said those quakes may have been related to activity around the world, noting a similar spike in massive earthquakes worldwide since 2002.

Brown's theory isn't new to Austin Holland, a research seismologist with the Oklahoma Geological Survey, who has been studying Oklahoma's earthquake swarm.

"I have heard similar arguments," he said. "When I say unprecedented, I mean never observed before by humans in an intraplate setting world-wide. That doesn't mean that in the geologic past sequences like this have not occurred.

"There are number of times in the historic past before we had seismic monitoring that we had seismicity clusters, but none of these upticks in seismic activity even come close to comparing to what we see today.

"I respect the work they are doing, but certainly feel that it is not the whole story."

Some researchers have linked earthquakes in oil and natural gas-producing states to wastewater disposal wells, leading many central Oklahoma residents at a town hall meeting in Edmond on Thursday to call for a moratorium on them.

Regulators said such unilateral action is not allowed under state law, while researchers like Holland contend additional data from operating injection wells will help provide answers about Oklahoma's earthquakes.

New rules also will allow the Oklahoma Corporation Commission to prevent operators from setting up disposal wells near faults that have produced earthquakes.

Global swarm

Brown said the increasing number of earthquakes rattling Oklahoma coincides with higher activity worldwide, as it has in the past. He also noted much of Oklahoma's earthquake activity has been in different areas than where companies have drilled for oil and natural gas.

His research shows Oklahoma has experienced 18 earthquakes with a magnitude of 4 of higher since 2002, while the world has seen a marked rise in major quakes. That includes the 9.0 quake in Japan that spawned a massive tsunami in 2011.

Brown said a similar Oklahoma earthquake swarm came and went in the 1950s.

There were 30 earthquakes reported over just more than a decade at a time when such records were compiled based on what people felt because there wasn't enough equipment to measure seismic activity, he said.

Brown said Oklahoma didn't get its first seismograph until 1961. Before then, the closest one was near St. Louis, so only the quakes that were large enough cause some damage were recorded.

He found newspaper reports from 1952 comparing an earthquake near El Reno to a bomb blast.

The range of people who felt that that 5.5 earthquake is roughly the same as the Nov. 7, 2011, quake centered on Prague, Brown said. That 5.7 temblor remains the largest in state history.

Brown said there have been similar earthquakes recently in Virginia and South Carolina, where there is no oil and gas exploration, while seismic activity seems to be increasing in Mexico, as well.

He said the Naica region in central Mexico has experienced more earthquakes than Oklahoma, with no more explanation.

"That's geology," Brown said. "You have about 10 percent of the data set to figure out what you know."

He said Oklahoma's earthquake swarm in the '50s eventually petered out, so he expects the same thing to happen again.

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