Earthquake in East County: Its not a matter of if, but when
Oregon easily could see a shaker on the same scale as 2011 quake in Japan
If you have ever wondered - perhaps out of curiosity, morbid fantasy or paranoia - what might happen if a major earthquake were to hit East Multnomah County and the Portland area, one place to look for an example would be Japan.
East County residents probably remember the news headlines on March 11, 2011, after a 9.0 magnitude earthquake, originating off the coast of northeast Japan, struck and caused a major tsunami that devastated the country's coastal areas a few minutes later.
More than 15,000 people died and thousands more were injured or reported missing. Including the disasters that followed - which included landslides, fires and the shutdown and failures of nuclear power plants - Japan reported around $230 billion in damage. Oregon coast residents may remember the strong currents and waves caused by the tsunami.
The earthquake and tsunami occurred because of movement of the underwater tectonic plates in the Pacific Ocean near Japan. Oregon's tectonic plates are a mirror of the plates near Japan, according to the Oregon Department of Geology and Mineral Industries. Off the Oregon coast, the Juan de Fuca Plate, which stretches more than 600 miles between northern California and British Columbia, Canada, is slipping below the North American Plate.
It's known as the Cascadia subduction zone. When enough energy is built up, earthquakes occur, the Department of Geology says. The last Cascadia subduction zone earthquake and tsunami was 312 years ago and caused widespread devastation on the Oregon coast.
That is just one of four types of earthquakes that could happen in Oregon, says James Roddey, director of communications for the American Red Cross' Oregon chapter.
'We live in one of the most dynamic places on earth' in terms of geologic forces, Roddey says about the Pacific Northwest. 'We have the potential for an earthquake larger than anything that will ever happen to California; an earthquake the equivalent of what happened to Japan last year.'
A former spokesman for the Oregon Department of Geology, Roddey describes himself as the prophet of doom when he talks about natural disasters for groups and media across the state and the country, with earthquakes being a major focus of his presentations.
Roddey spoke to the West Columbia Gorge Chamber of Commerce during a luncheon Wednesday, Feb. 22 - a day that just happened to be the one-year anniversary of the 6.3-magnitude earthquake in Christchurch, New Zealand.
Roddey brings up the Christchurch earthquake in his presentations as an example of how a major city was devastated by a 12-second earthquake on a Tuesday afternoon, with 181 deaths and widespread damage throughout its downtown and suburbs. The estimated costs to rebuild range from $20 billion to $30 billion, and thousands of homes and buildings need to be demolished.
Roddey cites a 2007 study by the American Red Cross with worrisome statistics: 54 percent of Americans don't prepare for disasters, and only one in 10 households have taken the steps to be prepared for a disaster.
One lesson to take away from his presentation: Don't expect the government to help you.
'2011 saw the most billion-dollar disasters in United States history, far exceeding any other year,' he says. 'As budgets get tighter and tighter, it's going to become more and more difficult to respond to billion-dollar disasters.'
East County's high-risk areas
Back in his American Red Cross office in North Portland, Roddey studies the Relative Earthquake Hazard Map, which covers the Portland-metro area.
Created by Metro Regional Government and the Oregon Department of Geology, the map evaluates the region for landslides, soil liquefaction and other risks in the event of an earthquake. The Portland Hills, East Bank and Oatfield faults are marked out.
Most of East Portland and East Multnomah County are lower risk for hazards than other areas. The neighborhoods south of Powell Boulevard and going into Clackamas County, however, are at a risk of earthquake-induced landslides because of the steep slopes in some areas.
The highest-risk areas are mostly on the west side of the Willamette River in the West Hills and western suburbs, as well as along the Columbia and Willamette rivers.
Roddey says the soils along the Willamette and Columbia rivers could see liquefaction, when earthquake shaking causes the soil to loosen and behave like a liquid. Liquefaction happened in Christchurch, undermining many foundations and severely damaging 80 percent of the water and sewage system.
'If you've built your building on liquefiable soil, there's not a whole lot you can do to (prevent liquefaction) if we get an earthquake,' he says.
Don't expect Mount Hood to be a safe haven. A major earthquake could dislodge glaciers or cause a debris flow down the mountain and rivers, he says.
'Nobody knows because we've never seen it happen,' he says.
East County lacks the skyscrapers of downtown Portland, which would be a dangerous place because of the falling glass and rubble.
But East County also has many brick-and-mortar buildings and big-box stores, which are not designed to shake during earthquakes, he says. Wood-frame buildings tend to do well in earthquakes, he says. Brick chimneys have potential to cause damage.
The roads, bridges and highways would likely suffer damage, hampering quick rescue efforts.
'It doesn't take a lot of damage to close a bridge,' he says. 'If you have one pillar column that suffers damage, is that enough to shut the bridge down completely until it's inspected?'
After an earthquake, up to 40 percent of businesses in the area could fail, according to a study by the Insurance Information Institute.
Although design codes for seismic safety started changing in the 1970s, strong seismic codes weren't put in place until the mid-1990s, Roddey says.
'Basically our state building codes now match California,' he says, adding that the West Coast has the highest seismic design standards in the United States.
Based on historic evidence, scientists say offshore earthquakes happen once every 250 to 500 years.
Could the Cascadia subduction zone earthquake happen anytime soon? The last one was 312 years ago.
'A scientist will never say yes,' Roddey says. 'What they will say is, 'We are within the window for one of these earthquakes.' '
If a 9.0-magnitude earthquake and tsunami were to originate off the Oregon coast, in a worst-case scenario, Roddey estimates the ground would shake 4 to 5 minutes and cause damage across more than 80,000 square miles; people in Salt Lake City may feel the shaking.
Fifteen to 30 minutes later, the tsunami would hit the coast. Luckily, it would be easier for most coast residents to get to higher ground before a tsunami, he says, unlike in Japan where the coastal areas are mostly at sea level. There also would be aftershocks.
Roddey doubts the tsunami would reach East County; instead, East County would probably see significant tidal fluctuations and surges from the Columbia River.
The number of fatalities would probably depend on when it happens, Roddey says, noting that more people would be at the coast in the summer or on Mount Hood in the winter. Wet soil might lead to landslides.
Corbett-area residents would probably do the best in the earthquake as people in rural communities tend to be better prepared for natural disasters, Roddey says.
'People in rural areas are used to dealing with power outages, storms that cause roads, bridges to be closed,' Roddey says. 'People in big cities take everything for granted' such as Internet, phone service and the quick response of authorities.
When asked how long people might have to wait for help, Roddey brings up Hurricane Katrina.
'If you think things are going to get back to normal fast or that help's going to arrive quickly, look at what happened in New Orleans,' he says. 'If you think the federal government is going to do a better job here in the Pacific Northwest than they did five or six years ago… It's not something I would like to bet on.'
At the very least, people should be friendly with their neighbors, Roddey says, noting that 95 percent of earthquake victims were rescued by their neighbors, on average.
Being prepared for the disaster
In the event of an earthquake, Gresham's Office of Emergency Management would be in charge of coordinating efforts between fire, police and public works on rescue and damage assessment.
Todd Felix, Gresham's emergency management coordinator, says the department pushes the message that residents should be prepared to be on their own for a long time. Given the possibility of widespread earthquake damage and the limited resources that emergency departments have, it could be a few days or a few weeks before people are helped, Felix says.
'If you're prepared for an earthquake, that goes a long way in being prepared for other types of disasters,' Felix says.
East County cities use the Map Your Neighborhood program and Neighborhood Emergency Response Teams efforts. Gresham is transitioning to Neighborhood Ready, a program that provides free comprehensive training to residents, Felix says.
Despite the devastation that the March 2011 earthquake and tsunami caused in Japan, Roddey notes that Japan was prepared for it in many ways. Residents were alerted through radio, television and text messages thanks to real-time earthquake and tsunami warning systems.
Tokyo, a metro region of 36 million people, was roughly the same distance from the epicenter of the earthquake as Portland would be from an earthquake epicenter off of the Oregon coast. Yet Tokyo reported just seven deaths, he says.
Ninety-five percent of the deaths in Japan were caused by the tsunami, he says.
'The earthquake itself is not a killer,' he says. 'It's the things that happen after the earthquake that cause the fatalities.'
Earthquakes are not the only natural disaster facing Oregonians; home fires are the most common disaster in the state. Despite all the risks, Roddey finds that many people put them out of mind and don't prepare.
'The possibility of it happening in our lifetimes is hit or miss,' he says, 'and it's human nature. If I don't have to think about it, I've got more important things to worry about today.
'The more you understand about what could happen, the more you feel in control about being prepared for it,' he says. 'Understand your hazards. The more you understand, the more confidant you will feel in dealing with those hazards.'