May 3, 2011
By Steven Sandberg
WHITE CITY, Ore. — Japan’s devastating earthquake in March was also able to cause damage across the Pacific Ocean at the Oregon and California coasts. It has researchers looking into what kind of damage a similar quake would cause in Southern Oregon.
Geologists say the Rogue Valley is in a unique position that makes it hard to tell the likelihood of a large-scale earthquake. While an earthquake may be hard to predict, the potential for a big one in the future is very real.
Southern Oregon University Geology Professor Charles Lane says he is constantly asked where and when an earthquake could hit Southern Oregon. His answer: under your feet, and probably while you were asking that question.
Relatively speaking, White City is a hotbed of seismic activity in the Rogue Valley, but that’s not saying much.
Professor Lane says a number of fault lines run through the Rogue Valley, and there’s evidence that others have been covered by rock over millions of years, but all of them are so ancient, any activity they ever see is too small to feel. Everything happening below the surface is miles underground, and he says that plays a major role in limiting the impact if there were a major earthquake.
“Where we’re standing right now, you and I, the subducting slab is about 40 kilometers below us,” says Lane.
He also says what makes our area unique is that it sits between two major areas of seismic activity, and both are doing different things. The Cascadian Subduction Zone in the Pacific Ocean is a compressional stress field, where the plates are bring crashed together. To the east, the Klamath Basin has a tensional stress field, with the faults pulling apart.
The unique geology makes it hard to tell when the big one could hit the Rogue Valley. Lane says it could be anytime from tomorrow, to 600 years from now, ranging in magnitude from a 1 to a 7.
“It could happen. Have we had anything like that in historical times here? No. The biggest things we’ve had around here in historical times have been the K Falls quakes.”
He says those answers may lie over the hill.
The last big earthquakes in southern Oregon happened in September 1993, when 5.9 and 6.0 magnitude quakes rocked Klamath Falls. The Klamath County Courthouse was damaged beyond repair, and needed to be replaced.
The earthquakes in 1993 served as a wakeup call for the community in Klamath Falls and it was after that when they realized the Klamath Basin is one of the most seismically active places in the entire state.
According to the National Earthquake Information Center, the amount of seismic activity in the Basin trumps the rest of Oregon; facts that people in Klamath Falls are well aware of now.
While it has them prepared for the future, they’re left wondering what’s going to come, and when it will hit. Without knowing for sure when a major earthquake will strike Southern Oregon, it means people need to be on guard.