California Tsunami Advisory today

[Galaxie Girl]

Yes, we're capable of getting tsunamis here, just like we're capable of getting tornadoes. Doesn't mean it's the most imminent threat, though. Tsunamis are worst in areas where: 1) there is a subduction zone fault near the coast (like Japan and Chile), 2) there is a harbor that basically funnels the tsunami energy into it (like Crescent City), or 3) both.

CA does not have a subduction zone fault. We are on the Ring of Fire, on the edge where 2 tectonic plates meet up and are creating quakes. The Ring of Fire has different types of faults on it. We have the San Andreas, which is a strike-slip fault. It's simply not capable of creating as big of a quake as a subduction zone fault. Also, since the San Andreas is inland, and not just off the coast, it won't create the immediate tsunami (striking the local shore just minutes after the quake) like what happened in Japan. The fault becomes a subduction zone fault up north, around Oregon I think..., and up into Alaska, which is why they were able to have the 9.2 back in 1964.

Yes, if we get a big quake in Alaska again like that, our harbors will have some damage, and we'll see some waves, but it won't be like the videos we all saw of Japan. We just don't get that here.

[expatCA]

Originally Posted by Charles

Supposedly the tsunami will only be two feet in southern California, probably wouldn't even notice it.
.

A 2 ft Tsunami could be devastating. It is only 2 ft high and miles long. The big "Tidal waves" are not what is the problem, it is the total mass of water behind that "little" wave.

If a genuine 2 ft tsunami hit, the damage would be huge. Watch so9me videos of Japan or the Indonesia one and the wave coming in was just a couple of feet in height.

[TheDragonslayer]

Originally Posted by Galaxie Girl

Yes, we're capable of getting tsunamis here, just like we're capable of getting tornadoes. Doesn't mean it's the most imminent threat, though. Tsunamis are worst in areas where: 1) there is a subduction zone fault near the coast (like Japan and Chile), 2) there is a harbor that basically funnels the tsunami energy into it (like Crescent City), or 3) both.

CA does not have a subduction zone fault. We are on the Ring of Fire, on the edge where 2 tectonic plates meet up and are creating quakes. The Ring of Fire has different types of faults on it. We have the San Andreas, which is a strike-slip fault. It's simply not capable of creating as big of a quake as a subduction zone fault. Also, since the San Andreas is inland, and not just off the coast, it won't create the immediate tsunami (striking the local shore just minutes after the quake) like what happened in Japan. The fault becomes a subduction zone fault up north, around Oregon I think..., and up into Alaska, which is why they were able to have the 9.2 back in 1964.

Yes, if we get a big quake in Alaska again like that, our harbors will have some damage, and we'll see some waves, but it won't be like the videos we all saw of Japan. We just don't get that here.

California does too have a subduction zone, I live on part of it. It starts at Cape Mendocino at a place called Shelter Cove and is part of the Cascadia Subduction zone and is capable of 9.0 rips of which the last one was January 26th of 1700 which is believed to have ripped from Cape Mendocino to its northern end, more than 700 miles. A subsequent tsunami inundated much of the California north coast, Oregon coast and the Washington coast. In March of 1992 we had a 7.2 megathrust earthquake that created a five foot tsunami, but the coast was also elevated by more than 4 feet in that earthquake. The cascadia subduction zone is also why we have volcanoes from northern California all the way to Canada.

[TheDragonslayer]

Here in northern California we have tsunami warning signs in all the low areas. There are areas inland nearly five miles with tsunami sand deposits. A mega thrust earthquake like the one that hit Sumatra in 2004 is not just a possibility, it is likely in the future and when it does, a tsunami would not just affect the northwest coast, but most of the Pacific rim countries. Tsunami heights can reach, depending on length of earthquake and distance from the coast, heights well over 30 feet and possibly up to 50 feet that would swamp cities like Eureka, Crescenct city and Brookings Oregon, and many coastal communities from the San Francisco bay area all the way to British Columbia, many of us here on the coast would barely have 15 to 20 minutes after the intense shaking before the first waves would hit us. These mega thrust earthquakes along the cascadia subduction zone hit about every 300 to 500 years and may also be cluster quakes where one very large quakes causes a domino affect triggering others along the rip zone to go off. The damage would be extreme with close to 10,000 killed from California to Washington and sections of land raised by upheaval and others dropped because of crustal rebound. It would be total chaos and has and will happen again.

[Galaxie Girl]

Originally Posted by TheDragonslayer

California does too have a subduction zone, I live on part of it.

You are right, it does technically start in way northern CA, I was thinking it started in Oregon, as I mentioned in my first post, I could not remember exactly off hand. My comments were generally regarding the effects on SoCal and San Onofre, which people have been discussing. San Onofre is not in the same danger that Fukushima was, nor are our ports. Of course they are shutting down San Onofre, so that is moot.

[TheDragonslayer]

The San Andreas fault terminates at Shelter cove in Humboldt count at the Gorda plate where the subduction zone starts. In March of 92 we had just moved up here and experienced our first small mega thrust earthquake, it shook for almost a minute and a half and did major distruction to the town of Ferndale. The coast line from Humboldt bay south to Shelter cove was raised nearly 4 feet in that 7.2 quake of which we were less than 2 miles from its epicenter. The land inland along the Eel river lowered by nearly the same four feet, much like tipping one edge of a teeter totter and the other end goes down while one goes up. Many people think that the San Andreas fault is the biggest risk in California, but the mega thrust earthquake potential is greater. If we here in far northern California get hit my 30 to 60 foot waves, then I believe a good part of coastal California would suffer extreme damage, at least as far down as San Francisco or Monterey. A 9.0 earthquake up here would surely be felt in Central California and cause a lot of damage across most of California, Nevada, Utah, Oregon and Washington, it would be the worse natural disaster to hit the US. I have studied earthquakes and siesmology for years.