NEWS - OKLAHOMA SEISMIC ACTIVITY MAY NOT BE OVER, EXPERTS SAY

Oklahoma's seismic activity may not be over, experts say

 

By Matt Dinger and Tiffany Gibson    

Published: November 7, 2011

The 5.6 magnitude earthquake that shook the state Saturday night did not cause significant damage nor have any serious injuries been reported — but the seismic activity may be far from over, scientists said.
The brunt of damage has been reported in Lincoln County, the epicenters of recent quakes, and in adjacent Pottawatomie County.
Minor damage to 12 homes was reported, and a stretch of U.S. 62 buckled in Lincoln County, said authorities. One building on the campus of St. Gregory's University in Shawnee also was damaged.
After the main shock, there were 12 temblors registering at magnitudes of 3.0 or higher and more than 70 quakes with magnitudes of 1.0 to 2.5, Oklahoma Geological Survey research scientist Amie Gibson said Sunday.
Those quakes — often known as aftershocks — are defined after the fact. A 4.7 magnitude earthquake that hit at 2:12 a.m. Saturday was initially thought to be the main shock until the 5.6 magnitude quake struck later in the day. That defined the earlier event as a foreshock, Gibson said.
“They're all individual earthquakes. People like to lump them in. It kind of helps people understand the sequence of events,” she said.
While scientists cannot predict earthquakes, Gibson said she would be surprised if they suddenly stopped considering the high amount of seismic activity over the weekend.
“With the pattern we're looking at, I don't see it stopping anytime immediately soon. I'd like it to stop, but I don't see that happening right now,” she said.
“We really hope that the 5.6 was the main shock because I don't want to see anything like that again, personally. It would be ignorant to assume anything right now, because who would assume that we'd have the two biggest ones in one day?” Gibson said.
Record-breakerBefore Saturday night, the strongest earthquake recorded was April 9, 1952, in El Reno, according to the geological survey. Its magnitude was 5.5.
U.S. Geological Survey geophysicist Don Blakeman said the agency doesn't know why Saturday's quakes struck so close together.
He said Oklahoma sits in the middle of the North American plate, which sometimes can build up pressure that would trigger an earthquake.
Oklahoma Natural Gas spokesman Don Sherry said that no ruptured gas pipelines have been reported.
“Pipelines are designed to withstand a lot of that stress. It doesn't appear that we've had any significant operation difficulties,” Sherry said.
Gas pipelines are monitored remotely 24 hours a day from the Oklahoma City office, he said.
ONG supplies about three-quarters of the state with natural gas, including Lincoln County.
“If we did experience some sort of damage associated with pipelines, we'd know about it pretty quickly. Just because they're buried beneath the ground doesn't mean we don't know what's going on,” Sherry said.
Engineers consider seismic activity when the pipelines are designed and installed, and pipelines routinely undergo inspection, Sherry said.
“Part of the engineering that goes into the construction of the pipeline is that there are these stresses present. There's going to be movement and shifting. I'm not saying they're impervious to earthquakes, certainly not, but there is a lot of thought that goes into the fact that the earth is constantly moving,” Sherry said.
Inspections madeThe state Transportation Department is inspecting bridges within 50 miles of the quake's epicenter. No bridges have been closed for repair, according the state Department of Emergency Management.
Also, the U.S. Army Corps of Engineers has inspected dams within 70 miles of the epicenter and found no problems, the emergency management department reported.
Betsy Randolph, an Oklahoma Highway Patrol trooper, said U.S. 62 was shut down about 1:20 a.m. Sunday in Lincoln County for resurfacing after the earthquake. The road was reopened an hour later.
Randolph said troopers on duty during the earthquake made cursory checks on the Capitol and other state buildings for damage. She said no damage was found, but the Department of Central Services will be doing more comprehensive examinations this week.
Crumbling bricksLincoln County Emergency Manager Joey Wakefield said the chimney on a two-story house collapsed near Prague. He said most of the damage was minor except for brick fireplaces that crumbled in several homes. There were 12 homes that sustained minor damage in the county, most involving damage to brick facades and cracks in wallboard, as well as roof and chimney damage, the state Department of Emergency Management reported.
MacArthur bridge between Kickapoo and Harrison also sustained damage caused by the earthquake, according to the Pottawatomie County sheriff's office Facebook page.
Shawnee Emergency Management Director Don Lynch reported on the city's website that two buildings and one residence received minor damage in the quake.
Part of the upper story of one of the walls at Neals Home Furnishings also fell, and one residence in the Aydelotte area had interior damage, Lynch wrote.
Four spires on top of Benedictine Hall at St. Gregory's University were damaged, and the turret on the southwest column was removed by a large crane and covered with a tarp to protect it from expected rain.
Medical emergenciesLara O'Leary, spokeswoman for the Emergency Medical Services Authority, said that paramedics were called on two earthquake-related calls Saturday night.
O'Leary said paramedics arrived to help a 72-year-old woman whose heart was racing after the quake.
O'Leary said paramedics also responded to help a 70-year-old man who fell in the shower during the earthquake.
He was taken to a hospital in good condition.
Wakefield said the injuries in Lincoln County were minor.
He said most of the injuries occurred when a brick fell on someone's arm or hand.
Two injuries were reported to the state health department: A Lincoln County man hit his head when trying to run out of his home during the earthquake and a Pottawatomie County woman cut her foot on broken glass after the earthquake.
Neither was hospitalized, according to the state emergency management department.