Posted on 03/13/2019 9:37:20 AM PDT by Sarcasm Factory
Americans have long dreaded the “Big One,” a magnitude 8.0 earthquake along California’s San Andreas Fault that could one day kill thousands of people and cause billions of dollars in damage. The Big One, though, is a mere mini-me compared with the cataclysm forming beneath the Pacific Northwest.
Roughly 100 miles off the West Coast, running from Mendocino, California, to Canada’s Vancouver Island, lurks the Cascadia Subduction Zone, where the Juan de Fuca Plate is sliding beneath the North American Plate, creating the conditions for a megathrust quake 30 times stronger than the worst-case scenario along the notorious San Andreas, and 1,000 times stronger than the earthquake that killed 100,000 Haitians in 2010. Shockwaves will unleash more destructive force against the United States and Canada than anything short of nuclear war, a giant asteroid strike, or a civilization-threatening super-volcano.
We didn’t even know a megaquake was coming until recently. When I was a kid, growing up in the mid-Willamette Valley in Oregon, earthquakes were California’s problem. Everyone, including scientists, thought us immune. Seismic hazard maps shaded California red and Oregon green. Geologists knew about the Cascadia Subduction Zone, but they thought that the Pacific and Juan de Fuca Plates weren’t locked—that the subduction was smooth, as if the continent were greased with lubricant. University of Washington geologist Brian Atwater proved them wrong in the late 1980s. Oregon had recorded no earthquakes since American pioneers colonized the territory in the nineteenth century, and the native population had no written records, but the earth itself keeps copious records of geologic events, once one knows where to look. Atwater’s first clue was the “ghost forests” along the Oregon and Washington coasts, drowned by seawater, covered by sand and landslide debris, and then exposed by beach erosion. According to tree-ring dating, every one of those forests was buried in 1700. Something extraordinary happened that year. Sea levels can’t rise six or more feet in a year. The coastline itself must have plunged into the ocean. Later, beach erosion exposed yet another ghost forest, in the small town of Neskowin; this one was 2,000 years old.
Atwater then collaborated with Japanese seismologist Kenji Satake, who dug up long-forgotten reports in his own country of an “orphan tsunami”—a violent tidal inundation not preceded by a local earthquake—that also occurred in 1700. Scientists scrambled for core samples of the ocean floor just off the American coast and found turbidites—layers of tsunami debris—that date back millennia and, most recently, again, to 1700, revealing a cycle that repeats itself every 300 to 600 years. The Cascadia Subduction Zone is not quiet, after all: it triggers catastrophic megathrust quakes, on schedule. “A fault that ruptures with this big of an earthquake every few hundred years is ragingly active,” says Yumei Wang, a geotechnical engineer at the Oregon Department of Geology and Mineral Industries (DOGAMI).
A 9.0 megathrust quake is too powerful even to be measured on the now-dated Richter scale. Megathrust quakes are measured instead on the Moment scale. Like its predecessor, the scale is logarithmic. Every whole-number increase represents an energy release 32 times greater than the whole number before it. An 8.0 earthquake is therefore 32 times more powerful than a 7.0, and a 9.0 roughly 1,000 times more powerful.
Of the three West Coast states, Oregon is the most vulnerable. “We’re less prepared here,” says geologic-hazard analyst John Bauer, also at DOGAMI. “Washington has had more earthquakes recently, so they’re better prepared, and California, too, of course. We didn’t adopt a culture of preparation until the mid-1990s.” Portland is also closer to the subduction zone than Seattle or Vancouver, so it will experience more violent ground shaking. And the Oregon coast is considerably more populated than anywhere else in the tsunami’s path. “We’re not overdue,” Bauer says. “But we’re due.”
Geologists knew about the Cascadia Subduction Zone, but they thought that the Pacific and Juan de Fuca Plates weren’t locked -- that the subduction was smooth, as if the continent were greased with lubricant. University of Washington geologist Brian Atwater proved them wrong in the late 1980s. Oregon had recorded no earthquakes since American pioneers colonized the territory in the nineteenth century, and the native population had no written records, but the earth itself keeps copious records of geologic events, once one knows where to look. Atwater’s first clue was the “ghost forests” along the Oregon and Washington coasts, drowned by seawater, covered by sand and landslide debris, and then exposed by beach erosion. According to tree-ring dating, every one of those forests was buried in 1700. Something extraordinary happened that year. Sea levels can’t rise six or more feet in a year. The coastline itself must have plunged into the ocean. Later, beach erosion exposed yet another ghost forest, in the small town of Neskowin; this one was 2,000 years old. Atwater then collaborated with Japanese seismologist Kenji Satake, who dug up long-forgotten reports in his own country of an “orphan tsunami” -- a violent tidal inundation not preceded by a local earthquake -- that also occurred in 1700.
Thanks Sarcasm Factory.
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I have a nephew and his wife still in NoCal, and I worry about them. She wants out, but he has the Family Stubbornness, which, in some males, borders on Family Stupidity.
If this article is on FR-FB, I will ping her to it.
I’ve been to several talks that Atwater has given over the years. It is pretty interesting the various disciplines that become involved. While not as precise or scientific, even native Indian lore makes sense taking into account the earthquakes, tsunamis and volcanic eruptions.
In Alaska there are native stories about the Ice God chasing a maiden that had been taken by the village men. And so the men had to flee. (It was really a glacier that had advanced and filled the valley that the original village was in, and the natives established another village on the south side of the bay away from the glacier!)
I was just talking to my daughter today. Sshe was age 3 when the Nisqually Quake happened. She remembers grabbing the leg of a table as I had taught her - and she comforted a girl that was crying. I looked it up this morning - it lasted for about 40 seconds.
I was below my desk at home in the basement - feeling the concrete slab feeling like the waves beneath a floating air mattress! And really hoping that it was fairly close by or their was going to be a LOT of damage.
The reason I brought up the earthquake with my daughter, and looking up the length of time (”Really!? It was only 40 seconds - I still remember that it seemed like forever!”) - I had just brewed a large pot of coffee.
The Cascadia quake could last up to 5 minutes long - and obviously with much more violent shaking. 5 minutes is about how long it takes to brew a pot of coffee. I almost always think of that every morning now.
“In Washington, that’s ONLY if Seattle, Tacoma, and Olympia are destroyed ...”
That very well could happen. Maybe not “destroyed”, but electrical out for 6 months, sewer and water out for a year. Before we learned of the Cascadia fault the emergency response was for Vancouver, B.C. to help Seattle and vice-versa, Seattle and Olympia and Portland, etc.
Now they have shifted the response to come from east of the mountains. So Spokane to Seattle, etc.
Airplanes with supplies will land at the big Boeing testing facility in Moses Lake. Then trucked to Snoqualmie Pass. I-90 at the pass has numerous bridges and elevated structures that will probably be compromised or destroyed.
Then helicoptered from the east side of Snoqualmie Pass and into Seattle and the Suburbs. Almost all of Seattle is only accessible over a bridge - so that should be interesting.
I know one guy that lives out in a small town on the Pennissula. He said the City Manager worked for awhile to develop evacuation plans, etc. After learning more and what they were up against, he quit his good job and moved to Spokane!
A lot of those places they won’t be able to evacuate everyone. The school kids probably if they keep all the buses near the school.
The elderly in the nursing home? They won’t even bother as they won’t have enough time.
Some of those towns will have only about 15 minutes from the time the earthquake starts to when the tsunami will hit. (And 5 of those minutes you are still hunkered under your desk.) Tsunami wave height could be from 20 to 60 feet on the coast. Seattle itself won’t see much of a tsunami.
However - if/when the Seattle fault goes (runs east-west below the stadiums in south Seattle, but not associated with the Cascadia fault) - then we very well could see major wave action and flooding in Lake Washington, Lake Union, etc.
An aside. They wanted to name the state “Columbia” after the great river. Nope - that would be too confusing with the “District of Columbia” which was the common name at the time for the nation’s capitol!
Were all gonna die!
On the other hand, the Bigg’un will solve America’s left coast leftist problem
The big Cat bulldozers won’t be the for clearing roads.
In our day the well-heeled, rich, connected, etc. all want to live on the coasts. The lesser folk live farther away and the insignificant live inland in the hills.
That geographic stratification suggests that the rich will die and the poor will survive.
“The big Cat bulldozers won’t be the for clearing roads.”
That doesn’t necessarily help anyone clear their front porch or yard of unsuccessful looters.
The Green New Deal will also prevent earthquakes. Just ask AOC.
Post-Modern Deconstructionism Architecture
Both may be used.
Don’t think so ... the gangs will be ‘foragiing’ Eastward for survival.
Post-Modern Deconstructionism Architecture
The cars falling out of the parking garage was really something. Kudos to the screen writer for thinking of it.
This would be inconvenient to my chosen life style, namely, living.
Therefore, it can not happen.
I know my constitutional rights to pursuit of happiness and being dead ain’t being happy.
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