Oklahoma joins a handful of other states relying on U.S. Geological Survey computers to figure out which bridges to inspect after an earthquake.
The Oklahoma Department of Transportation says the USGS ShakeCast system will save time and money. Engineer Steve Jacoby said the way ODOT used to do it meant all bridges in a 50-mile radius of Prague were inspected after a 5.6 magnitude shaker in 2011.
"And that generated inspections of 772 bridges. With our interim protocol, which is more based on science, of 30 miles, that reduced to 189 bridges," Jacoby said. "With ShakeCast, 32 bridges needed inspection."
Similarly, last September’s Pawnee 5.8 magnitude earthquake would have lead to 336 inspections under the old ODOT protocol, 167 under the updated one but just 38 with ShakeCast.
ShakeCast automatically generates a prioritized list of bridges to inspect based on a quake’s magnitude and the state’s inventory of bridges. Each bridge has a fragility curve based on factors like age, length, style and condition.
"The fragility curves, they've been validated through actual earthquakes in California: the 1989 Loma Prieta earthquake, the 1994 San Fernando Valley earthquake. So, we feel pretty confident in their ability to predict seismic resistance or seismic capacity," Jacoby said.
The Loma Prieta earthquake was a 6.9, while the San Fernando Valley earthquake was a 6.7.
Jacoby said ShakeCast information comes out as fast as anyone else gets USGS data.
"Last week in Edmond, you know, everyone felt it. I think it happened at 9:56 [p.m.], and there about 10:08, 10:10 p.m. during the news, they had word that it was a 4.4," Jacoby said.
California, Washington, Utah, Oregon and Idaho are the other states using or soon to be using ShakeCast.
