PORT TOWNSEND — With tsunamis fresh in the collective consciousness after the March 11 disaster in Japan, North Olympic Peninsula residents can learn more about the regional hazards in a public presentation Sunday at Fort Worden State Park.
The Port Townsend Marine Science Center’s Quimper Geo Group will sponsor the talk on earthquake and tsunami hazards in the Port Townsend area at the park’s USO building from 3 p.m. to 4:30 p.m.
The presentation is open to the public, with a $5 suggested donation. Admission is free for members of the Port Townsend Marine Science Center.
Featured speakers
Featured speakers will be Brian Atwater, U.S. Geological Survey geologist and noted tsunami expert, and Ron Tognazzini, a retired civil, structural and earthquake engineer from Sequim.
Earlier this month, Atwater addressed forums in LaPush, Neah Bay, Port Angeles and Sequim.
The magnitude 8.9 quake that rocked Japan earlier this month happened in a continental plate boundary similar to the Cascadia Subduction Zone, which runs north and south in the Pacific Ocean about 75 miles offshore from LaPush.
Atwater said at the Port Angeles forum March 10 that when the next earthquake hits the Cascadia subduction zone off the coast of Washington state, Neah Bay residents will have a little more than a half-hour to hightail it to higher ground, while Port Angeles residents will have about an hour and a half and Port Townsend residents about two and a half hours.
Atwater’s research found that the last 500-year subduction zone quake happened Jan. 26, 1700, with a resulting tsunami that was probably 10 feet above the high-tide line.
He warned that the 500-year interval is only an average. The “big one” could happen anytime.
Atwater will review the known history of Pacific Northwest earthquakes and tsunamis. He will also turn to eyewitness accounts of recent tsunamis in Indonesia and Japan and the public-safety lessons they provide.
Discovery Bay research
Tognazzini will present tsunami research performed by Marley Iredale, a former Sequim High School student who did research in Discovery Bay in 2008 and 2009.
“She’s away at college,” he said. “That’s why I’m presenting it.”
Iredale, 18, won multiple awards and caught the attention of seismologists like Atwater for her study, “Evaluating Tsunami Risk in Discovery Bay, Wash.”
Iredale spent some 500 hours studying sand beds under Discovery Bay and found signs of nine tsunamis over the past 2,100 years.
Her research suggests that tsunamis have hit Discovery Bay about twice as often as the 500-year tsunamis formed by the subduction zone earthquakes in the Cascadia Subduction zone.
Iredale is attending college at Washington State University in Pullman, Tognazzini said
“Because this is a very timely subject, I’m presenting as part of her results the risks that she found — the actual hazard assessment on the North Olympic Peninsula,” Tognazzini said.
Earthquake-triggered landslides — both aboveground and underwater — can trigger localized tsunamis that have hit the North Olympic Peninsula more often than the widespread subduction zone tsunamis, Tognazzini said.
Tognazzini spent much of his career working for the Los Angeles Department of Water and Power.
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Reporter Rob Ollikainen can be reached at 360-417-3537 or at rob.ollikainen@peninsuladailynews.com.
