People across the Northwest are terrified of the “Big One,” a catastrophic earthquake along Oregon’s Cascadia fault that could occur at any time and is expected to kill thousands of people and cause significant economic damage.
Over the 4th of July weekend, three major earthquakes, with magnitudes from 5.4 to 7.1, rocked southern California. A week later, a 4.6-magnitude earthquake hit the Seattle region.
None of those earthquakes occurred on the Cascadia fault, where the Big One will take place, but according to the Pacific Northwest Seismic Network, there are small earthquakes happening daily across the Northwest, ranging in magnitude from 0.3 to 2.9.
These earthquakes do not mean that the Big One will happen tomorrow. “Prediction is so hard,” said Dr. Diego Melgar, an assistant professor who researches seismology at the University of Oregon. “We can tell you there’s the fault, it has definitely made earthquakes, it’s been a while since it made an earthquake, but when it will next make an earthquake is anybody’s guess.”
The Cascadia fault line lies off the coast and stretches from Northern Vancouver Island to Cape Mendocino, California, dividing the Juan de Fuca and North America plates.
Melgar said the Juan de Fuca plate is moving inland at a rate of four centimeters per year, or the speed at which your nails grow, and is slowly slipping beneath the North America plate edge. Major earthquakes occur on this fault line every 300 to 500 years, he said, and the last one is estimated to have occurred just over 300 years ago.
The Big One, when it comes, is expected to be at least a magnitude 8.0, and Oregon is not prepared for the disaster.
Melgar said the first line of defense against earthquakes are building codes, and “building codes mean knowing what level of shaking your building is going to be exposed to and building accordingly.” If building codes are up to par, there should be few collapsed buildings.
Scientists didn’t confirm the Cascadia fault line was an active subduction zone until the late nineties, Melgar said. “That means that any building built before that was built under the assumption that there are no earthquakes in the Pacific Northwest,” he said.
Melgar said in California, building codes going back to 1933 are acceptable, and it is illegal to build brick buildings. “Walk around Eugene and tell me how many brick buildings you see,” he said. “Or Portland, or Seattle.”
He said California has done things like provide tax breaks for individuals who choose to retrofit their homes.
Melgar said one of the most important things individuals can do is inform themselves. “We just need to coexist with earthquakes,” he said. “We just need to understand what they are.” People can also lobby their representatives in Congress to raise awareness that building codes need continued improvement, he said.
But when an earthquake hits, lifelines may get cut off and thousands of people may be in need at once. Earthquake kits are one way for people in Oregon to be prepared. Melgar said he recommends having enough supplies to survive for about two weeks. He recommended having canned goods, batteries and warm clothes pre-stocked in a kit somewhere easily accessible.
Amelia Holmes, who at the time of the interview was the Cascades region spokesperson for the Red Cross, said the Red Cross recommends having a “go kit” ready. “We know that we are at risk of experiencing a potentially very dangerous earthquake where we live, and we know that we won’t have a warning when it happens,” Holmes said.
She said everyone should have “a set of emergency supplies that is enough for not only you but everyone in your household.” This includes enough food and water for each person in the household for two weeks. In the event of a major earthquake, she said, that’s how long it could take for emergency responders to reach some people.
Red Cross also recommends keeping a first aid kit, gas shut-off tool, flashlight, screwdriver and extra clothes in the emergency kit. Holmes said it is also wise to have a kit at your place of work and in your car.
“The reality is a disaster like a major earthquake can happen at any time, and it can happen to anyone,” Holmes said.