State geologists want better quake preparedness here

YAKIMA, Wash. -- Washington state geologists are calling for better earthquake preparedness in the aftermath of a quake off the coast of northern Japan that spawned a tsunami and devastated the country both physically and economically.

The example of Japan, one of the world's most earthquake-prepared countries, dealing with the long-term consequences of the event is a cautionary tale to less prepared areas such as this state, Central Washington University professor Tim Melbourne said.

Melbourne, who teaches seismology, geophysics and introductory geology, said Japan has a well-recorded history of powerful earthquakes that has led to much greater investment in improved infrastructure as well as public education on disaster preparedness.

"They (the Japanese) really get it, and we don't," said Melbourne, who is also the director of the Pacific Northwest Geodetic Array.

Melbourne said the state faces an infrequent but high earthquake risk with the strongest geologic activity likely in the Puget Sound region and off the Pacific coast.

"Everyone knows (a powerful earthquake) is in our future," he said. "The problem is, how do you tell someone to think hard about something that might not occur in their lifetime?"

Though geologists can't predict earthquakes with pinpoint precision, Melbourne said recorded history of the area lets them use what has happened in the past to prepare for what may come.

Though Puget Sound faces little to no tsunami threat, a 9.0-magnitude quake similar to the one that struck off the coast of Japan would cause widespread destruction to infrastructure, namely ports and freeways crucial to the region's economy, Melbourne said.

Its effects would be felt in Yakima as well, but geologists said the damage would be minimal.

"There'll be some shaking, but not enough to cause significant damage," Bill Steele, coordinator for the University of Washington Seismology Laboratory, said.

Though Yakima doesn't reside in the same high risk area as Puget Sound, Steele said more geologists in recent years have turned their attention to Central and Southeast Washington to reassess earthquake risks.

What makes the state earthquake-prone farther inland is something called the Olympic-Wallowa Lineament, a series of faults that stretch from the Olympic Mountains to the Wallowa Mountains through Walla Walla County.

Some of those faults are still being discovered, and any new information could change what was previously thought about the region's potential for earthquakes, Brian Sherrod, a researcher with the U.S. Geological Survey, said.

Sherrod, who works extensively in the Yakima Valley, said he and his team recently found evidence of three previously undocumented faults in Central Washington and have submitted their results for peer review. He said they were found in the Wenas Valley, on the southside of Umtanum Ridge and in Kittitas County near Boylston Ridge, respectively.

Sherrod said it's not clear what that could reveal about the area, but proof already exists of 7.0-magnitude earthquakes having occurred there -- meaning they can happen again.

An important part of understanding the area's earthquake risk that geologists are struggling with is dating the events that formed these faults, Sherrod said. He said the problem lies in a lack of organic material in the soil along the faults that is used for radio carbon dating.

"We have to have those materials to work with and at least one of these sites we had nothing, zero," Sherrod said.

The largest recorded earthquake in Washington state occurred east of the Cascades near Lake Chelan on Dec. 15, 1872. It was estimated at a magnitude 7.0 and was felt from British Columbia, Canada, to Oregon and from the Pacific Ocean to Montana.

The last significant earthquake to hit Washington state was the Feb. 28, 2001, Nisqually Quake in the Puget Sound region, which measured at a 6.8 magnitude. It did minor damage and lasted about 45 seconds, but it was felt throughout the state, including in Yakima, where play at the high school state basketball championships in the SunDome was temporarily halted.

For geologists, though, there are few hypotheticals. It's never if, but when the next devastating quake will strike, even if it doesn't happen in our lifetime.

"I think people should know they live in earthquake country now," Steele said. "There are definitely big earthquakes in your future."

* Contact Mike Faulk at 509-577-7675 or mfaulk@yakimaherald.com. Follow him on Twitter at @Mike_Faulk.