An extensive article published by Outside Magazine looks at what would happen if an earthquake similar to the megaquake in Japan happened off the Washington and Oregon coasts in the Cascadia Subduction Zone.
As you might imagine, the scenario is not a good one.
The feature not only looks at the physical aspects of a megaquake in the CSZ – the quake itself, the tsunami and the damage – but how people might likely react to it, including those that may not believe a tsunami is on the way.
Here are excerpts from a timeline published in the article:
The CSZ sends out a so-called P-wave, traveling at 13,000 miles per hour. First it hits the coast, then hits Portland and Seattle.
After a short lull, the S-waves arrive. Think of what a garden hose does when you whip it. These waves are the same, and they last much longer than the P-waves. I this scenario, they will last for more than four minutes.
Buildings begin to shake apart. Bricks fall onto side¬¬¬walks. Hot water heaters topple, exposing natural gas pipes and starting fires. Piers along the Seattle waterfront begin collapsing.
The northern Pacific coastline suddenly sinks five feet in a matter of minutes. Glass and steel office buildings in Seattle start to buckle. Even with their earthquake-resistant design, they weren’t built for this kind of earthquake.
The worst is over for Seattle and Portland. But for people on the coast, it’s just the beginning. A tsunami that could flood as much as six miles inland is now about 35 miles offshore.
Lifeguards try to get people to leave the area, but some people aren’t convinced. Either tsunami warning sirens have not gone off, and even if they have, some people ignore them.
The first wave is about 25 miles offshore. Boat owners along the coast remember that tsunamis usually just pass under vessels in the open ocean without incident, so they try to get as far out into the sea as possible.
Those who have jumped into their cars are driving away from the coast, but the quake has chopped up the roads. Only SUVs and four-wheel-drive trucks can get through. Some good Samaritans help those who are stranded, but others leave them behind.
The leading edge of the tsunami hits at flash flood speed. You would have to be able to run a mile in 5:30 in order to outrun it. Those who didn’t heed the warnings to leave grab onto anything they can as the wave takes their feet out from under them.
Those in Seattle and Portland who actually have power or who can use their smartphones watch live reports of the tsunami. Most likely, the wave won’t reach them.
Secondary tsunami pulses batter the coast. They’ll continue for eight to ten hours.
In the end, the expected death toll is in the thousands, whether it was from falling buildings, the tsunami or a medical condition triggered by the event.
Read the entire article at outsideonline.com
Thanks to seattlepi.com for spotting this story.