When Seattle's next tsunami hits the city, its steep hills may be its salvation. But you had better head for them fast.
NOAA Scientists just beginning to map where a big wave would hit needed to look no farther than the vulnerable shorelines around Elliott Bay: West Point, Interbay, lower Queen Anne, downtown, Harbor Island and West Seattle.
If a magnitude-7.3 earthquake rumbles out of the recently discovered Seattle Fault, Harbor Island would tilt toward the bay and the Duwamish River estuary would drain. But within two minutes the water would ricochet off the north shore of the bay and wash back eastward, flooding three square miles of low-lying areas.
Maps that scientists have drawn up show that a tsunami generated by an earthquake in the Seattle Fault could send up to 16 feet of water roaring ashore, swamping two marinas, inundating the Seattle Aquarium, Ivar's Acres of Clams, Myrtle Edwards Park and the state ferry dock in what used to be tidelands downtown.
Scientists also calculate that a tsunami could move from the west side of the bay to the city waterfront in as little as two minutes, possibly closing port docks and washing fuel and other hazardous material into the water. If a tsunami occurs, "it's going to be an environmental disaster for Elliott Bay," said Steve Martin, operations manager for the city's emergency-management unit. Also, with a shutdown of the port "it's going to be an economic disaster for the city and it would be an economic disaster for the state."
The Puget Sound area hasn't had a tsunami, an earthquake-generated wave, from the Seattle Fault in more than 1,000 years. But scientists say it will happen. As the December tsunami ravaged Southern Asia, scientists had already begun to predict and map where a big wave would hit here. And Seattle and other cities are considering expanding their emergency-warning systems to include more tsunami alerts, though there is some question about how effective the systems will be.
More updated advice for the old "drop, cover and hold" earthquake procedure might be: When the earthquake's over, get out of the way of the wave.
"It has happened in the past, and we expect it to happen in the future," said geologist Timothy Walsh of the state Department of Natural Resources.
Walsh and four scientists from the National Oceanic and Atmospheric Administration in Seattle completed a state- and federally funded study in 2003 on the effects of local tsunamis after about a year's work.
Officials said more detailed, block-by-block analysis is needed to determine which neighborhoods need to be evacuated. With current maps, "what we're getting now is best guesses," Martin said.
And the maps will likely need to be redrawn. Evidence from Indonesia suggests wave heights of 80 feet -- far higher than thought. That means that assumptions in the maps in Washington, including 30-foot wave heights on the coast, may not reflect the worst-case scenario. The waves could be higher, the water faster and deeper and the damage more devastating.
Martin said there's a low likelihood of a tsunami hitting Seattle. Walsh said a magnitude-7.3 quake would occur, on average, about once in every 2,500 years.
But the research, recently facing cutbacks, is now accelerating on the heels of the December tsunami.
And later this year, emergency service officials in Seattle and Bellingham will meet with Walsh and other experts to discuss exactly where tsunami waters would land. Scientists have found evidence that another tsunami hit Whidbey Island about 300 years ago. "It has happened in the past, and we expect it to happen in the future," Walsh said. An earthquake on the east-west Seattle Fault could push up the floor of Elliott Bay, sending a wall of water as high as 16 feet crashing into docks, businesses and maybe waterfront condominiums.
The wall of water could sweep away cars, buses and trains. Thousands of gallons of gasoline and diesel stored in tanks on Harbor Island could create an environmental nightmare if they ruptured and the wave mixed their contents with bay water. Some water could enter the West Point sewage-treatment plant through a driveway.
The city has an alert system linked to the National Weather Service and state emergency officials by radio, phone and teletype. This spring, the city will add seismographs to three environmental monitoring stations to be added at Myrtle Edwards Park, the Pier 30 Cruise Terminal and a fire station on Alaskan Way, each with speakers that can sound an alarm and broadcast an evacuation message. The city already has a "reverse-911" system that sends phone alerts to businesses and residents in areas where a flood might hit.
The additions will be part of a $278,000, federally financed system designed to also detect bioterrorist attacks and track the spread of radiation from a terrorist's "dirty bomb," Martin, of the city's emergency management unit, said. Limited funding will confine the improvements to the central waterfront, leaving to the future alarms for other vulnerable shorelines in Interbay, Magnolia or West Seattle.
Martin thinks Seattleites may have half an hour to get out of tsunami's way. But if the wave moves across the bay within two minutes it will be harder to respond to and Walsh, the state geologist, says more elaborate, satellite-based warning systems are pointless. Ground levels in Seattle and other Sound cities rise above of the water quickly. Martin and Walsh say the best protection for people outdoors is to head for higher ground when an earthquake comes.
The tsunami question adds another dimension to the debate about replacing the city's Alaskan Way Viaduct. Critics of a proposed tunnel are seizing on the new tsunami information.
"We believe that building the tunnel on the Seattle fault could put hundreds of citizens in danger if an earthquake ruptures the lining and floods the tunnel," wrote Gene Hoglund of Citizens for an Elevated Solution to state House Speaker Frank Chopp. The most recent map shows flooding "would cover most of the waterfront." Hoglund has written a similar letter of concern to Seattle officials, who recently endorsed the tunnel idea.
Dave Dye, urban corridors administrator for the state Transportation Department, said both a tunnel and a new elevated viaduct will be designed to withstand the Seattle Fault earthquake that would create the giant waves, but a tunnel would hold up better than an elevated structure by being more completely anchored to the ground. Unless hit by a huge projectile the wave pushes forward, "I would suspect it would survive," he said.
TSUNAMI HAZARD ZONES
This map estimates the extent of flooding from a tsunami produced by a 7.3-magnitude earthquake on the Seattle Fault, based on computer modeling. Scientists think an earthquake of that strength would flood parts of Seattle's waterfront as much as 16 feet, inundating waterfront buildings, restaurants and docks and swamping marinas. More recent information suggests the waves could be higher. Seattle and other cities plan to expand the telephone and alarm-based warning systems but experts say it is more important to know where the wave might hit.
NOAA Scientists just beginning to map where a big wave would hit needed to look no farther than the vulnerable shorelines around Elliott Bay: West Point, Interbay, lower Queen Anne, downtown, Harbor Island and West Seattle.
If a magnitude-7.3 earthquake rumbles out of the recently discovered Seattle Fault, Harbor Island would tilt toward the bay and the Duwamish River estuary would drain. But within two minutes the water would ricochet off the north shore of the bay and wash back eastward, flooding three square miles of low-lying areas.
Maps that scientists have drawn up show that a tsunami generated by an earthquake in the Seattle Fault could send up to 16 feet of water roaring ashore, swamping two marinas, inundating the Seattle Aquarium, Ivar's Acres of Clams, Myrtle Edwards Park and the state ferry dock in what used to be tidelands downtown.
Scientists also calculate that a tsunami could move from the west side of the bay to the city waterfront in as little as two minutes, possibly closing port docks and washing fuel and other hazardous material into the water. If a tsunami occurs, "it's going to be an environmental disaster for Elliott Bay," said Steve Martin, operations manager for the city's emergency-management unit. Also, with a shutdown of the port "it's going to be an economic disaster for the city and it would be an economic disaster for the state."
The Puget Sound area hasn't had a tsunami, an earthquake-generated wave, from the Seattle Fault in more than 1,000 years. But scientists say it will happen. As the December tsunami ravaged Southern Asia, scientists had already begun to predict and map where a big wave would hit here. And Seattle and other cities are considering expanding their emergency-warning systems to include more tsunami alerts, though there is some question about how effective the systems will be.
More updated advice for the old "drop, cover and hold" earthquake procedure might be: When the earthquake's over, get out of the way of the wave.
"It has happened in the past, and we expect it to happen in the future," said geologist Timothy Walsh of the state Department of Natural Resources.
Walsh and four scientists from the National Oceanic and Atmospheric Administration in Seattle completed a state- and federally funded study in 2003 on the effects of local tsunamis after about a year's work.
Officials said more detailed, block-by-block analysis is needed to determine which neighborhoods need to be evacuated. With current maps, "what we're getting now is best guesses," Martin said.
And the maps will likely need to be redrawn. Evidence from Indonesia suggests wave heights of 80 feet -- far higher than thought. That means that assumptions in the maps in Washington, including 30-foot wave heights on the coast, may not reflect the worst-case scenario. The waves could be higher, the water faster and deeper and the damage more devastating.
Martin said there's a low likelihood of a tsunami hitting Seattle. Walsh said a magnitude-7.3 quake would occur, on average, about once in every 2,500 years.
But the research, recently facing cutbacks, is now accelerating on the heels of the December tsunami.
And later this year, emergency service officials in Seattle and Bellingham will meet with Walsh and other experts to discuss exactly where tsunami waters would land. Scientists have found evidence that another tsunami hit Whidbey Island about 300 years ago. "It has happened in the past, and we expect it to happen in the future," Walsh said. An earthquake on the east-west Seattle Fault could push up the floor of Elliott Bay, sending a wall of water as high as 16 feet crashing into docks, businesses and maybe waterfront condominiums.
The wall of water could sweep away cars, buses and trains. Thousands of gallons of gasoline and diesel stored in tanks on Harbor Island could create an environmental nightmare if they ruptured and the wave mixed their contents with bay water. Some water could enter the West Point sewage-treatment plant through a driveway.
The city has an alert system linked to the National Weather Service and state emergency officials by radio, phone and teletype. This spring, the city will add seismographs to three environmental monitoring stations to be added at Myrtle Edwards Park, the Pier 30 Cruise Terminal and a fire station on Alaskan Way, each with speakers that can sound an alarm and broadcast an evacuation message. The city already has a "reverse-911" system that sends phone alerts to businesses and residents in areas where a flood might hit.
The additions will be part of a $278,000, federally financed system designed to also detect bioterrorist attacks and track the spread of radiation from a terrorist's "dirty bomb," Martin, of the city's emergency management unit, said. Limited funding will confine the improvements to the central waterfront, leaving to the future alarms for other vulnerable shorelines in Interbay, Magnolia or West Seattle.
Martin thinks Seattleites may have half an hour to get out of tsunami's way. But if the wave moves across the bay within two minutes it will be harder to respond to and Walsh, the state geologist, says more elaborate, satellite-based warning systems are pointless. Ground levels in Seattle and other Sound cities rise above of the water quickly. Martin and Walsh say the best protection for people outdoors is to head for higher ground when an earthquake comes.
The tsunami question adds another dimension to the debate about replacing the city's Alaskan Way Viaduct. Critics of a proposed tunnel are seizing on the new tsunami information.
"We believe that building the tunnel on the Seattle fault could put hundreds of citizens in danger if an earthquake ruptures the lining and floods the tunnel," wrote Gene Hoglund of Citizens for an Elevated Solution to state House Speaker Frank Chopp. The most recent map shows flooding "would cover most of the waterfront." Hoglund has written a similar letter of concern to Seattle officials, who recently endorsed the tunnel idea.
Dave Dye, urban corridors administrator for the state Transportation Department, said both a tunnel and a new elevated viaduct will be designed to withstand the Seattle Fault earthquake that would create the giant waves, but a tunnel would hold up better than an elevated structure by being more completely anchored to the ground. Unless hit by a huge projectile the wave pushes forward, "I would suspect it would survive," he said.
TSUNAMI HAZARD ZONES
This map estimates the extent of flooding from a tsunami produced by a 7.3-magnitude earthquake on the Seattle Fault, based on computer modeling. Scientists think an earthquake of that strength would flood parts of Seattle's waterfront as much as 16 feet, inundating waterfront buildings, restaurants and docks and swamping marinas. More recent information suggests the waves could be higher. Seattle and other cities plan to expand the telephone and alarm-based warning systems but experts say it is more important to know where the wave might hit.
