Corvallis similar to New Zealand quake zone

2011-02-24T06:15:00Z Corvallis similar to New Zealand quake zoneBY GAIL COLE, Gazette-Times Reporter Corvallis Gazette Times
February 24, 2011 6:15 am  • 

The Willamette Valley has similarities with Christchurch, New Zealand, the city of approximately 377,000 that was struck by a magnitude 6.3 earthquake Tuesday.

Robert Yeats, professor emeritus of geology at Oregon State University, said Wednesday that, like Christchurch, the Willamette Valley has lots of sediment-filled soil caused by flooding.

Tuesday's earthquake hit Christchurch in the middle of the working day. The city's location on a fault (which was not discovered until a year ago) and its sediment-filled soil made the impact of the earthquake more devastating than if it had rumbled up from far below the Earth.

Corvallis was built atop a fault that runs from Philomath through town to the area near Crescent Valley High School, which has been studied by faculty at OSU. However, no one knows if this fault is active or not.

He said computer-generated photographs using LIDAR - Light Detection and Ranging - technology can be used to create topographic maps of the region to determine more faults and map out where landslides could hit.

But although geologists are able to study an area affected by an earthquake by mapping any aftershocks, analyzing the deformation of the Earth's crust and measuring the earthquake's depth, no one can predict when an earthquake will hit.

"It's not exact science, and it's not easy to do," Yeats said.

Tuesday's earthquake in New Zealand actually was an aftershock from a magnitude-7 quake that struck the area 25 miles outside Christchurch almost six months ago. Yet this week's quake was far more devastating (as of Wednesday afternoon, the death toll was 71). It could have been far worse had it not been for strict New Zealand building codes, Yeats said, bringing up the earthquake in Haiti for comparison.

About a quarter of a million people died in the magnitude-7 quake that struck Haiti's capital of Port-au-Prince on Jan. 12, 2010. Many of them were crushed under the weight of buildings that had not been built to any structural standards and with little or no thought to how they would resist an earthquake.

The City of Corvallis upgraded its building codes in 1973, and new structures are seismically sound. Historical buildings that have undergone seismic retrofitting include the Majestic Theatre and City Hall, where such upgrades are under way.

"We have pretty good building codes, but what we don't have is anything that requires a developer to locate possible faults," Yeats said.

Yeats has studied earthquakes for nearly 40 years, and wrote several books, including "Geology of Earthquakes," the only earthquake-centered textbook of its kind. Two of his books - "Living with Earthquakes in the Pacific Northwest" and "Living with Earthquakes in California" - were published by OSU Press.

His current book project is titled "Active Faults of the World."

Contact reporter Gail Cole at 541-758-9510 or at gail.cole@lee.net.

 

 

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