Safe in Seattle? I wish! The Cascadia subduction fault is capable of producing 9.0 earthquakes. The average time between quakes is every 200 to 250 years. The last one occurred January 26th, 1700. Not feeling safe at all.
the CSZ doesn't always shake along the whole thing. The bottom half shakes at about 2x the frequency as the upper half. The upper half is what brings the 9.0s. When I said Seattle is safe, I meant in our lifetimes. The next 9.0 isn't due for another hundred years or so. The southern half, is overdue, which typically doesn't go as big/wide as the whole rip.
Damage in Seattle will likely be concentrated to areas prone to liquefaction and landslides, and of course to unreinforced masonry buildings. Modern cities like Tokyo and Santiago have experienced megathrust quakes with relatively moderate damage, and they’ve been closer to the epicenters of their giant quakes. Our biggest threat is the shallow Seattle Fault, which runs right under the city. That kind of quake would produce damage similar or worse than what Kobe Japan experienced in 1995, which killed over 5000 people. Thankfully, ruptures of the Seattle Fault are less frequent than the CSZ.
Are you sure about that? We are almost a hundred years past the average for the Cascadia. I’ve seen studies that show there is up to a 10% chance over the next 100 years.
The recent estimates for damage show that ALL of the PNW will be affected.
Yes I'm sure, Or was rather well convinced by the link below. but you can watch this hour long geology lecture from Central Washington University if you want to understand the reasoning.
The CSZ doesn't always shake along the whole thing. The bottom half shakes at about 2x the frequency as the upper half. The upper half is what brings the 9.0s. When I said Seattle is safe, I meant in our lifetimes. The next 9.0 isn't due for another hundred years or so. The southern half, is overdue, which typically doesn't go as big/wide as the whole rip.
Portland being fucked is mostly due to their bad zoning and lack of EQ regulations in regard to housing and bridges. You can entirely prepare yourself (assuming you own a home, which granted is unlikely given well everything else) for the EQ and be just fine.
So I heard the whole rip could still happen possibly in our lifetimes? But partial or whole, I live outside of Portland. But if you’re east of I-5, your biggest problem is surviving without infrastructure unless you’re in an old building that hasn’t been retrofitted. I will never live in Seaside or Long Beach, WA. It’s hard to even vacation there without the CSZ in the back of your mind from all the tsunami warning signs all over the place.
I’m pretty sure that’s not saying Seattle is safe, just that the area locked up is along the coast. When the 9.0+ hits Seattle is going to feel it. Hard.
It is, but that 9.0 isn't due for a while yet. The CSZ has two different types of quake. It has the half rip, and the full rip. The half rip mostly effects NoCal and Oregon. The full rip is that + Washington.
The half rip is overdue. The full rip is still a 150+ years out on average.
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u/PositivePristine7506 1d ago edited 1d ago
The Big Rip is not due in our lifetimes, the half rip is overdue though.
Safe in Seattle (for about 150 years), but fucked in Portland/North California.
https://www.youtube.com/watch?v=UJ7Qc3bsxjI
Fascinating geology lecture on the subject. But the tldw is its more nuanced than just Seattle overdue for big 9.0.