Tulsa World: Oklahoma observatory keeps watch on Earth's seismic pulse

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Oklahoma observatory keeps watch on Earth's seismic pulse

By JEFF BILLINGTON World Staff Writer
Published: 7/28/2008 2:07 AM
Last Modified: 7/28/2008 2:26 AM

For more information about the Oklahoma Geological Survey Observatory in Leonard

LEONARD — When an earthquake is registered either in Oklahoma or on the other side of the world, Jim Lawson is one of the first to notice.

Lawson, 69, is the chief geophysicist at the Oklahoma Geological Survey Observatory in Leonard, one of nine observatories in Oklahoma, with two more planned near Oklahoma City.

"We've got two in Oklahoma City that are a little bit of a new concept. They've got a digitizer that talks directly to the Internet, so there's no communication other than just an Internet connection," said Lawson, who has been the chief geophysicist at the facility since 1970.

In 1960, the Jersey Production Research Oil Co., which is now Exxon, built the original observatory. The location was selected because it was seismically and magnetically quiet, which meant there were no heavy industrial and traffic vibrations to disturb the site, and it was within driving distance of Jersey's Tulsa headquarters.

Originally, the site had magnetic and seismic recorders to document the ground motion, Lawson said.

"They recorded on drums and photo paper in the darkroom," he said.

Around 1970, the observatory became a part of the University of Oklahoma. In 1978, the facility became part of a state agency, the Oklahoma Geological Survey.

Two years ago, the facility again became a division of OU, Lawson said.

"And now we're doing pretty much the same, except now we're doing it with digits instead of photo paper," he said.

There are many fault lines that run through the state that produce seismic readings on an almost daily basis, Lawson said. Most are never felt by the average person.

"A lot of them are completely inactive, but what we don't have is one big fault coming from out of the state. They're coming from out of the New Madrid. We've got really no connection to New Madrid," he said.

The New Madrid seismic zone, the site of one of the largest earthquakes in North America, is located within the central Mississippi Valley and extends from northeast Arkansas, through southeast Missouri, into northwestern Tennessee and western Kentucky to southern Illinois.

"The New Madrid fault produces about three little earthquakes a week and (in) those particular states, Tennessee and Missouri, the universities there have 30 or 40 stations near," he said.

Between 1811 and 1812, four large earthquakes, with magnitude estimates greater than 7.0 on the Richter scale, occurred during a three-month period, with hundreds of aftershocks, Lawson said. Instruments were installed in and around the area in 1974 to closely monitor seismic activity. Since that time, more than 4,000 earthquakes have been located. Most have been too small to be felt, he said.

"The call we frequently get is, 'Can I get a fault map of Oklahoma?' I never say yes or no, I say why, because I explain to them that places where there are long faults there often are not earthquakes," he said.

The Leonard observatory registers earthquakes around the world. On Wednesday, the observatory documented the 6.8 magnitude earthquake that struck off the northern Japanese coast.

The Leonard observatory also has another distinction. A small group of Russians, who had a nuclear monitoring site there, were allowed to record seismic waves received from an underground nuclear blast site in Nevada, Lawson said.

On June 1, 1990, President George H.W. Bush and Soviet President Mikael Gorbachev signed a protocol for a Russian test building to be located near the observatory. About seven years later, after the Russia-United Kingdom-United States nuclear testing ended, the Russians gave the site back to the U.S., turning the $1 per year leased land back to Oklahoma.

Red-and-white street signs at the observatory, in both English and Russian, are still located near the observatory.

"A lot of people were not aware that there was an average of one nuclear test every nine days, from 1945 to 1990, with France, Britain, China, United States and Russia," Lawson said.

The Russian visit wasn't really publicized because officials felt protesters might demonstrate against their visit, he said.

Jeff Billington 581-8369
jeff.billington@tulsaworld.com By JEFF BILLINGTON World Staff Writer

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