First Oregon ShakeOut

An estimated 37,000 Oregonians participated in the first “Great Oregon ShakeOut” on January 26 – the state’s first comprehensive earthquake drill. The skills they learned could save their lives in the event of a major earthquake.

Researchers at Oregon State University – who in the mid-1980s were among the first in the nation to suggest that Oregon is subject to massive subduction zone earthquakes – have helped define the faults placing Oregon residents at most risk, supported efforts to boost building codes, and more recently have studied earthquake disasters all over the world to identify what makes the difference between tragedy and survival.

“It’s been a long struggle to convince Oregonians that these risks are real, that it will happen here and we have to prepare for it,” said Bob Yeats, a professor emeritus of geology at OSU and international leader in earthquake science and history. “Earthquakes can’t be predicted with any precision, but they can be prepared for, we can save lives, and the Oregon ShakeOut is a great thing to help raise the awareness of what we should do.”

That preparation, OSU experts say, should be reflected in everything from personal knowledge to homeowners analyzing the risk areas in their own residences, disaster plans, community infrastructure, well-enforced building codes, zoning considerations and better public awareness of risks.

Cascadia Roulette

At 79, Bob Yeats has changed the way we prepare for earthquakes in the Northwest and inspired a new generation of researchers. Read about his accomplishments.

Yeats wrote a book published in 2004, Living with Earthquakes in the Pacific Northwest, which outlines in more detail many of the same issues that will be explored in the Great Oregon ShakeOut.

The catastrophic event a year ago in Haiti provides perhaps the most vivid illustration of earthquake disasters, and a 7.2 magnitude earthquake in southwest Pakistan on January 19 was a reminder of the Earth’s near-constant tectonic activity. But these events are just some of many and can have markedly different results.

  • In 2003, an earthquake of magnitude 6.6 occurred on a strike-slip fault near Bam, Iran, which was constructed largely of aging mud/brick structures. Almost 90 percent of the buildings were destroyed and almost 40,000 people died, nearly one out of every four residents.
  • A few days later, the San Simeon earthquake in California hit on a reverse fault with magnitude 6.5. No buildings with even partial seismic retrofitting collapsed, and only two people died.

“We saw essentially the same thing with the recent 7.1 earthquake in New Zealand, where they have strong building codes and no one died,” Yeats said. “And of particular interest for us in Oregon should be the Chilean subduction zone earthquake last February, which was huge at magnitude 8.8 and is quite similar to what we may expect on the Oregon Coast during its next subduction zone quake.”

According to Scott Ashford, professor and head of the School of Civil and Construction Engineering at OSU, Chile is actually a case of what Oregon should aspire to.

Earthquake stress in the Pacific Northwest

This image shows the general motion of Pacific Northwest landforms as the terrain is squeezed and moved by tectonic forces. (Graphic courtesy of Rob McCaffrey, Bob King and Suzette Payne, Portland State University)

“Because it has had subduction zone earthquakes with much more frequency than the Pacific Northwest, the buildings, roads and infrastructure in Chile are actually more earthquake resistant than here in Oregon,” Ashford said.

“There was loss of life in Chile, but all things considered they did pretty well in maintaining what I think of as their lifelines, the roads, bridges, power supplies and other things that you most urgently need in a disaster,” he said. “We haven’t made the progress in that area that we should, and I think we’re already starting to forget some of the lessons and awareness we had just a year ago after the Chilean quake.”

Ashford said a good first step would be to assess all of the state’s vulnerabilities in the event of a major earthquake, and then prioritize which areas to tackle first with whatever funding can be made available.

Things could be worse, and in many parts of the world they are. Later this spring Yeats will publish another book, Active Faults of the World, which will explore the many cities around the world which have the potentially disastrous combination of poor construction practices, heavy population and major, active earthquake faults. Ranging from Kabul (Afghanistan), to Karachi (Pakistan), Istanbul (Turkey), Tehran (Iran), Caracas (Venezuela), and Kingston (Jamaica), there are many more tragedies waiting to happen.

The good news, OSU researchers say, is that Oregon, like Chile, does not fit that desperate category – but that’s not saying there isn’t room for improvement.

“As this statewide drill illustrates, we’re just now beginning the type of widespread, public education about earthquake risks and preparation that we’ve needed for a long time,” Yeats said. “That should continue permanently, but there’s also more that could be done.”

Among possible improvements, the OSU researchers said, might be:

  • Crustal faults in Oregon, aside from the Cascadia Subduction Zone, should be better identified;
  • It could be required that the sites of proposed construction be evaluated for earthquake fault and landslide hazards, as is done in California;
  • The landslide risks associated with earthquakes should also be better considered in housing, road and infrastructure decisions;
  • More attention should be paid to “lifeline” infrastructure such as electricity and gas supplies, water and sewers, roads and bridges;
  • Existing programs of seismic retrofitting should be encouraged and expanded;
  • More work could be done with LiDAR sensing technology to identify faults and landslides, which is available in Western Oregon through the Oregon Department of Geology and Mineral Industries;
  • Efforts should be expanded to educate not just residents but also tourists on the Oregon Coast about the risks and disaster plans associated with subduction zone earthquakes and resulting tsunamis. Many of those who died in the Chilean earthquake were tourists on summer vacation.

Although the subduction zone earthquake issues have gotten most of the recent headlines, Yeats said, the risks from crustal faults in the Pacific Northwest should not be underestimated. The Corvallis Fault runs right underneath a local high school and through residential areas. The Portland Hills Fault runs through downtown Portland. It’s not known whether either of these faults is active or not.

Similar crustal faults underlie both Tacoma and Seattle, the other two major urban areas in the two states, and in one case near Seattle a major public works facility is being built right on top of a fault.

“There are people all over the Pacific Rim who understand and have prepared for earthquake disasters they know will happen,” Yeats said. “Now we’re gaining a better understanding of those risks here in Oregon and Washington. There’s still a lot to do, but it’s a good start.”

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