In recent years, it has seemed as if Portland has had the best weather and the least number of catastrophes of anyplace in the world. Although we have recently been near a fire catastrophe in the Columbia Gorge, it seems not to have done nearly as much damage there as was at first feared, and the main inconvenience to Portland was a closed I-84 and very smoky air.
But, we now have good reason to know that someday we are going to get whammed bigtime – by a plate boundary earthquake that can only be compared to the similar earthquake recently experienced in Japan, in which tsunamis swept away whole villages, and a nuclear power plant melted down.
Our experience, when that time comes, will be considerably different. As we gaze at Houston, monumentally and unprecedentedly inundated by over FIFTY INCHES of rain from the stalled Hurricane Harvey, with a substantial number of all the homes in this huge metropolitan area flooded and at least temporarily uninhabitable, we may wonder if our catastrophe will be as bad as that. Perhaps Hurricane Irma makes us wonder the same.
Alas, it will be worse. Much worse.
Twenty years ago, we didn’t even know we were subject to such an earthquake disaster. Scientists were puzzled by tree stumps way out from shore at locations on the coast – a suggestion that somehow the land was higher or the ocean lower in the recent past. When they began to explore the possibility of a large subsidence, they came across a record in Japan which not only confirmed a megathrust Cascadia Subduction Zone earthquake and tsunami, but put a date on it – January 26, 1700, at about 9 p.m.
You see, there had been an “orphan tsunami” – one not connected with any earthquake felt in Japan – which washed ashore and caused widespread destruction. It had traveled across the Pacific from the coast of Oregon and Washington, and the known speed of such tidal waves allowed the fixing of the time and date of the massive temblor here which caused it.
The magnitude estimate for the earthquake is around 9; the rupture it caused in the seafloor off the Northwest was 600 miles long; and the amount of displacement in that rupture over 60 feet. The violent shaking felt far inland would have lasted perhaps five minutes. Five minutes can be an eternity.
Further excavation found evidence that this earthquake was just one of a long series that extends back well over two thousand years at least. They have occurred every 300 to 900 years – notice that it has been over 300 years since the last one! – and the average interval has been around 575 years. So the next Big One may not occur in our lifetime – or in the lifetimes of our great great great grandchildren – but it also really could happen later today!
We confess that we are not looking forward to covering this huge news event in THE BEE, but when it happens, THE BEE will – we hope – cover it well for Southeast Portland.
Because the timing in uncertain is no reason not to at least start making preparations, because – as we said – the aftermath of this disaster here would make Houston’s misfortune from Hurricane Harvey look like a walk in the park.
Just to start with: All utilities will be out, and every underground pipe system will be broken in many places. That does not simply mean no electricity or Internet or phone service for quite a long time, but it also means no natural gas service, no water service, and no sewer service – perhaps for many months. Homes will in many cases be too dangerous to enter, and may have collapsed enough to make any resources kept inside totally inaccessible.
No food, no gasoline available, and resupply will be a long time coming.
But…surely there will be a massive relief effort arriving soon afterward, as happened in Houston?
No, not likely.
It will arrive in bits and pieces at intervals, despite the very best intentions. That’s because all the interstate highways in our region will be impassible, due to the collapse of many overpasses and bridges. The airports will no doubt be impassible to airplanes because of damage to the runways. Helicopters could get in, but mass provisioning for a million and a half people just in the Portland metro is not likely via helicopters, and the streets leading to where the helicopters are may be impassible – and local vehicles may not have any fuel to get there.
In fact, there is only one bridge in the whole State of Oregon expressly built to survive such an earthquake and remain in service. Guess which one. Yes, the new Sellwood Bridge. Anyone on one side of the Willamette River trying to get to the other side will either have to take a boat, or the Sellwood Bridge. That will pose special challenges for the people who live here in particular!
Meantime, at least one, and probably both of the Interstate Bridges carrying Interstate Five cross the Columbia River will have collapsed into the river, carrying the many vehicles on them at the time down to their doom. Too bad we didn’t replace those with quakeproof bridges a few years ago when we had the chance. We will be very lucky indeed if the I-205 bridge is usable; most likely it won’t be. We will be cut off.
Our next Megathrust earthquake almost certainly will be the worst catastrophe in the history of the United States so far, and recovery will take a very long time. Are you prepared to live in your back yard for months, in hot or cold or wet weather, with no utilities, no bathroom, and no fresh food?
Maybe now you are starting to get the idea of why you have been hearing so much lately about preparing for this earthquake. Maybe you should look into joining the NET (Neighborhood Emergency Team) in your own neighborhood, and getting some of the training from Portland Fire and Rescue about how to be effective in helping your family and neighbors in case something like this happens in our lifetime. It would be useful knowledge to have in the case of any sort of disaster.
You don’t have to prepare all at once.
But you should, at the very least, think hard about it – and get started with at least some preparation steps while you still have the luxury of time to do it!