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ENLARGE
Reminiscent of California school drills in the 1960s, James Roddy, a state geologist, sits under a table Wednesday in Roseburg.
A Cascadia Subduction Zone earthquake ...
• will register as a magnitude 9 or greater.
• can last three to five minutes.
• will directly affect 10 million people or more living from northern California to British Columbia.
• has occurred 14 times in the last 4,800 years or an average of one time every 343 years.
• will cause parts of the coast will drop 3 or more feet.
• will cause tsunami waves 30 to 70 feet tall.
• has a one-in-six chance of occurring in the next 50 years.
• Information provided by James Roddy with the Oregon Department of Geology.
• will register as a magnitude 9 or greater.
• can last three to five minutes.
• will directly affect 10 million people or more living from northern California to British Columbia.
• has occurred 14 times in the last 4,800 years or an average of one time every 343 years.
• will cause parts of the coast will drop 3 or more feet.
• will cause tsunami waves 30 to 70 feet tall.
• has a one-in-six chance of occurring in the next 50 years.
• Information provided by James Roddy with the Oregon Department of Geology.
Imagine strolling along the beach at Winchester Bay or Seaside and suddenly feeling a hard, violent shaking that knocks people off of their feet and crumbles roads and bridges.
Farther inland — like in Roseburg — long, rolling earthquake waves will sweep through communities, destroying streets and fragmenting Interstate 5.
After several minutes of rumbling, all will be still. But the calm will be short-lived. About 15 minutes after the shaking ceases, the coast line that spans Oregon, Washington and British Columbia will be slammed by a wall of water.
Tsunami waves stretching more than 100 miles long and 30 to 70 feet tall will crash into the coast. The river of displaced water will flood buildings and destroy whatever lies in its path, before drawing back into the ocean to gain strength and returning to cause more destruction; the process will continue for 10 to 12 hours.
“It’s going to be a horrific, scary, terrible event,” said James Roddy of the Oregon Department of Geology and Mineral Industries.
The event will be comparable to the Sumatran earthquake and tsunami that originated in the Indian Ocean, devastating multiple communities and claiming hundreds of thousands of lives Dec. 26, 2004, Roddy said.
About 150 people filled the Rose Theater at Roseburg High School Wednesday evening to listen to Roddy talk about the mega earthquake and massive tsunami that are expected to hit the Oregon Coast.
“I’ve been called Chicken Little,” Roddy told the audience. “I prefer The Prophet of Doom, and you’ll see why.”
About 50 to 60 miles off of the Oregon Coast lies the 600-mile long Cascadia Subduction Zone, which stretches from northern California to British Columbia.
The world is comprised of several plates. The Cascadia Subduction Zone is the point where the North American Plate meets the Juan de Fuca Plate. The two plates bump up to each other, causing the Juan de Fuca Plate to dive, or subduct, beneath the North American Plate.
The subduction of the Juan de Fuca Plate causes the North American Plate to bulge upward as pressure builds beneath it. Eventually, Roddy said, the pressure will cause the plates to rupture, which will result in a magnitude 9 or greater earthquake. The rupture will also cause a massive tsunami that will send six miles of water to the coast.
“A tsunami is not a wave,” Roddy said. “It is a river of water.”
In the last 10,000 years, researchers have found evidence of 20 great earthquakes along the Cascadia Subduction Zone, the most recent was at about 9 p.m. Jan. 26, 1700, Roddy said. Geologists examine soil patterns for tsunami sands that serve as proof that tsunamis have crashed into coastal communities.
American Indian tribes along the coast have for centuries known about the massive quakes and tsunamis, Roddy said. Indians developed oral histories, myths and stories about the events in order to teach their children how to respond when the water begins to rise.
“They created this culture of awareness that they passed on for thousands of years,” Roddy said.
That awareness saved lives during major disasters, and Roddy said he wants to see people in the Northwest develop that same kind of awareness.
Not many people were killed when the Sumatran tsunami struck the Adaman Islands — located near the subduction line where the tsunami originated — because the people there had oral histories similar to those of the American Indians, Roddy said, that taught them how to stay safe. When the tsunami reached the unprepared villages in Thailand, though, tens of thousands of people were killed.
“There was no reason for that many people to die in that tsunami,” Roddy said.
The subduction zone where the massive Sumatran earthquake and tsunami originated is of similar size to that of the Cascadia Subduction Zone, he said.
“The Sumatran earthquake woke up a lot of people in the Pacific Northwest because we didn’t know how big one of these could be,” Roddy said.
Roseburg resident Debbie Cooley said she became more aware of tsunami possibilities after the 2004 event in the Indian Ocean but thought Roddy’s presentation made the likelihood seem more real.
“It was a real huge eye opener to what could happen,” Cooley said.
Kathy Glockner said she missed most of the presentation Wednesday, but said as a member of a citizen emergency response team in Roseburg she thought the presentation was valuable for people in the community to attend.
“It’s not a matter of if,” she said, “it’s a matter of when.”
And when the magnitude 9 earthquake and following tsunami do strike the Oregon Coast, Roddy said people can survive — even those in coastal cities — as long as they prepare in advance and head to high ground when the water begins to rise.
“Earthquakes and tsunamis of themselves are not catastrophes,” he said. “We make them that way.”
• You can reach reporter Marissa Harshman at 957-4202 or by e-mail at mharshman@nrtoday.com.
Farther inland — like in Roseburg — long, rolling earthquake waves will sweep through communities, destroying streets and fragmenting Interstate 5.
After several minutes of rumbling, all will be still. But the calm will be short-lived. About 15 minutes after the shaking ceases, the coast line that spans Oregon, Washington and British Columbia will be slammed by a wall of water.
Tsunami waves stretching more than 100 miles long and 30 to 70 feet tall will crash into the coast. The river of displaced water will flood buildings and destroy whatever lies in its path, before drawing back into the ocean to gain strength and returning to cause more destruction; the process will continue for 10 to 12 hours.
“It’s going to be a horrific, scary, terrible event,” said James Roddy of the Oregon Department of Geology and Mineral Industries.
The event will be comparable to the Sumatran earthquake and tsunami that originated in the Indian Ocean, devastating multiple communities and claiming hundreds of thousands of lives Dec. 26, 2004, Roddy said.
About 150 people filled the Rose Theater at Roseburg High School Wednesday evening to listen to Roddy talk about the mega earthquake and massive tsunami that are expected to hit the Oregon Coast.
“I’ve been called Chicken Little,” Roddy told the audience. “I prefer The Prophet of Doom, and you’ll see why.”
About 50 to 60 miles off of the Oregon Coast lies the 600-mile long Cascadia Subduction Zone, which stretches from northern California to British Columbia.
The world is comprised of several plates. The Cascadia Subduction Zone is the point where the North American Plate meets the Juan de Fuca Plate. The two plates bump up to each other, causing the Juan de Fuca Plate to dive, or subduct, beneath the North American Plate.
The subduction of the Juan de Fuca Plate causes the North American Plate to bulge upward as pressure builds beneath it. Eventually, Roddy said, the pressure will cause the plates to rupture, which will result in a magnitude 9 or greater earthquake. The rupture will also cause a massive tsunami that will send six miles of water to the coast.
“A tsunami is not a wave,” Roddy said. “It is a river of water.”
In the last 10,000 years, researchers have found evidence of 20 great earthquakes along the Cascadia Subduction Zone, the most recent was at about 9 p.m. Jan. 26, 1700, Roddy said. Geologists examine soil patterns for tsunami sands that serve as proof that tsunamis have crashed into coastal communities.
American Indian tribes along the coast have for centuries known about the massive quakes and tsunamis, Roddy said. Indians developed oral histories, myths and stories about the events in order to teach their children how to respond when the water begins to rise.
“They created this culture of awareness that they passed on for thousands of years,” Roddy said.
That awareness saved lives during major disasters, and Roddy said he wants to see people in the Northwest develop that same kind of awareness.
Not many people were killed when the Sumatran tsunami struck the Adaman Islands — located near the subduction line where the tsunami originated — because the people there had oral histories similar to those of the American Indians, Roddy said, that taught them how to stay safe. When the tsunami reached the unprepared villages in Thailand, though, tens of thousands of people were killed.
“There was no reason for that many people to die in that tsunami,” Roddy said.
The subduction zone where the massive Sumatran earthquake and tsunami originated is of similar size to that of the Cascadia Subduction Zone, he said.
“The Sumatran earthquake woke up a lot of people in the Pacific Northwest because we didn’t know how big one of these could be,” Roddy said.
Roseburg resident Debbie Cooley said she became more aware of tsunami possibilities after the 2004 event in the Indian Ocean but thought Roddy’s presentation made the likelihood seem more real.
“It was a real huge eye opener to what could happen,” Cooley said.
Kathy Glockner said she missed most of the presentation Wednesday, but said as a member of a citizen emergency response team in Roseburg she thought the presentation was valuable for people in the community to attend.
“It’s not a matter of if,” she said, “it’s a matter of when.”
And when the magnitude 9 earthquake and following tsunami do strike the Oregon Coast, Roddy said people can survive — even those in coastal cities — as long as they prepare in advance and head to high ground when the water begins to rise.
“Earthquakes and tsunamis of themselves are not catastrophes,” he said. “We make them that way.”
• You can reach reporter Marissa Harshman at 957-4202 or by e-mail at mharshman@nrtoday.com.
