Remapping Oregon Tsunami Evacuation Zones

March 12, 2011

By Stacia Kalinoski

EUGENE, Ore. — Communities across the Oregon coast headed for higher ground Friday morning after tsunami warnings were issued.

But now an Oregon coastal geologist is revamping the way Oregon residents would evacuate their homes and businesses.

Oregon coastal geologists have been making tsunami evacuation maps since the mid ’90s.

But it was the 2004 Indian Ocean tsunami that spurred Dr. Robert Witter with the Oregon Department of Geology and Mineral Industries to aim for more accurate ways to remap all 362 miles of the Oregon coast.

His team in Newport has a $2.8 million grant to remap coastal cities. The four-year-long project started in 2009 and will finish in 2013.

The devastating tsunami wave that hit Japan prompted emergency crews along the Oregon coast to turn on the sirens and flashing lights.

In terms of actually evacuating coastal residents, the method all along has been to follow the Oregon Tsunami Evacuation Map.

“This shows the area of the tsunami evacuation and the areas point to where to go,” Witter said, referring to the current Oregon Tsunami Evacuation Map.

But Witter says this map is too vague, so he’s creating a more efficient model for emergency crews and residents to use.

There are now two maps based on the two likeliest tsunami scenarios in Oregon. One is a distant tsunami, and the other is  close to Oregon.

“What we’re trying to do is depict the two different hazards because there’s extreme differences,” Witter said.

The first scenario is considered less hazardous, like the earthquake that hit Alaska in 1964.

“It travels over four hours to reach Oregon and floods most of downtown Bandon,” Witter said, pointing to the simulation on his computer.

But the second one would be an earthquake in the Cascadia Subduction Zone.

“We’re preparing for the big one,” Witter said.

The orange area shows where people should go in the event of a smaller scale tsunami, like one traveling from Japan or Alaska.

The orange and yellow area is the evacuation zone for the worst case scenario: a Cascadia tsunami.

“It’s easier for emergency crews to evacuate the orange area than to evacuate this entire area, which would be unnecessary for a distant event (like Alaska),” Witter said.

So how is he drawing up these maps? It’s based on previous earthquakes in this area, as well as geophysical models of how earthquakes create tsunamis. His team has already created 15 different scenarios.

“We’re using the best available data and the most sophisticated technology so we have high confidence that we’re covering the range of tsunami inundation that’s likely in the future,” Witter said.

Witter’s team has just completed mapping the area between the Northern California border up to Coos Bay, and he says they’re preparing the maps for distribution.

Right now they are working on the area around Tillamook County, and than in 2012 they will begin looking at the Central Oregon Coast.

Whitter currently holds community evacuation drills along the coast to help people prepare for tsunamis like the one that hit Friday.

For more information, click here.

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