New Seismic Monitoring Station Installed in Oklahoma

By PHYLLIS ZORN, Enid News and Eagle | August 12, 2013

In a pasture northeast of Carrier, three scientists with Oklahoma Geological Survey have installed a new seismic monitoring station.

The earthquake monitoring station is composed of a seismometer, digitizer and cell modem, tucked into a water barrel with a bilge pump to keep it all dry. A solar panel stands overhead to supply power to the station.

Austin Holland, research seismologist with OGS, told the Enid News & Eagle that the station has been in the works for more than six months, its $20,000 installation cost paid for with grants.

Installation was moved forward following a series of small earthquakes in the Medford area. A July 31 tremor registered 2.9 on the Woods-Anderson magnitude scale, with an epicenter 2.67 miles north of Medford.

People in the Medford area reported hearing a loud boom followed by the shaking.

Amie Gibson, OGS research scientist, provided a report sent to OGS by a Medford resident.

“On the southwest side of Medford, we heard a boom, and felt the house shake,” Amanda Bell reported. “It felt as if a vehicle had driven into the house. We thought it was an explosion of some kind, since you could feel the pressure shock.”

Holland said an earthquake makes two major waves. The primary wave, which travels through the earth, goes before the secondary wave. It was the impact of the primary wave that created the “boom” sound, Holland said. The secondary wave creates the shaking of the earthquake.

Holland said Oklahoma now has 15 monitoring stations around the state. The next closest seismic station is outside Ponca City, but that one needs some work and might be removed instead of repaired, Holland said.

Another is located south of U.S. 412 and east of Woodward.

The digitizer, the “brains” of the seismic station, transmits data to Holland’s office at the University of Oklahoma in Norman.

“I can get to the memory from the office,” Holland said. “That one will hold a couple months of data.”

Oklahoma has seen an increasing number of earthquakes, Holland said.

“At most, 10 percent of our earthquakes can be attributed to hydraulic fracturing, but otherwise our number of earthquakes are on an uptick,” Holland said.

He noted wastewater disposal wells might be the cause of some of the earthquakes. But drilling is not the reason for most of them.

“We have naturally occurring earthquakes in Oklahoma,” Holland said.

Holland said the July 31 earthquake is not a cause for alarm, and “drop, cover and hold on” is the standard recommendation for a large earthquake. The next drill, the “Central U.S. Shakeout,” is scheduled for October, Holland said.

The likelihood of an earthquake large enough to do damage remains low, Holland said.

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