Tuesday, March 15, 2011

1700 Cascadia earthquake

Most of you more erudite among us know about the 1700 Cascadia quake. The Indians were still talking about it in the 1850’s when the white man first showed up. Some of the old Indian legends say that Humboldt bay was a grassy field before 1700, and great redwood forests sunk into the ocean. The quake was estimated as between 8.7 to 9.2. Some of the Indian stories passed down through the generations said “When the sky growls seek low ground, when the ground growls seek high mountains”. The legend referred to lightning and earthquakes. The Indian people knew about tidal waves. They also saw Humboldt field turn into Humboldt Bay. In our own lifetimes we have seen the beach along Petrolia lift 4 feet out of the sea, and Kings Peak grow 16 inches taller. We know that it can happen.

The Cascadia Subduction zone extends from Vancouver Island in Canada to the triple junction off Petrolia. When the 1700 quake happened it moved 66 feet, for over a 620 mile stretch. Just for reference, The Japanese quake that just happened, the island moved 8 feet. I'm not sure how long the rupture zone was. What just happened in Japan might have been a small payback for the 1700 tidal wave that we sent their way. I can’t find how large the wave that hit Japan was, but it was very large, and was recorded in their history.

The cascadia subduction zone creates an earthquake every 4 to 5 hundred years. So, we still have a couple of hundred years before another one hits. We should know a lot more about earthquakes by then, maybe everything will be alright, right?

However, earthquakes and volcanoes have a tendency to go in swarms around the ring of fire that surrounds the Pacific Ocean. So, lets take a survey. Chili had an earthquake recently, New Zealand had an earthquake, and Japan had an earthquake. Who does that leave, oh yeah, US! Somewhere between Mexico and Alaska is over-ripe for an earthquake. They say before an earthquake the animals and fish act strangely. One of the things that happened before the Loma Prieta Earthquake that small fish choked the harbors and died off. They are doing that exact thing as we speak. What do they know that we don’t. Should So Cal be alarmed?

Getting back to the Cascadia quake of 1700, whole forests of trees sunk into the ocean. The broken off trees can STILL be seen at very low tides when the sand washes away and exposes the old trees that are normally buried. They say that this not only can, but WILL happen again. I don’t think that I would sleep very well living next to the ocean after this, knowing what we know can happen. But, human nature being what it is, will probably force people to run to the beach and take photos of the 90 foot wave that is expected to hit the coast in the next Cascadia Subduction Zone fracture.

1700 Cascadia earthquake



Anonymous said...

The Cascadia quake generated a tsunami that headed west and hit Japan and was documented there in 1700. Don't know how severe the wave was but they did document it.

Rose said...

That big storm we had a few years back uncovered one of those petrified forests under Trinidad Beach. It was quite amazing to stand there. It's all covered back up now.

imagine if they really have found Atlantis, too - which they suspect was covered up by a tsunami as well.

"We have found a geological formation not typically found in nature," Freund told Efe.
The structure and layout of the boulders discovered indicate human intervention, and they could be the remains of the ancient island, Freund said.
The team's findings are outlined in a special to air Tuesday in the United States on the National Geographic Channel and that will be broadcast in Spain this June.

Ernie Branscomb said...

I was watching TV tonight and guess what, they had this exact post on Nat Geo. The only difference is they said that cascadia earthquakes are only 200 years apart and we are 100 years overdue. I guess that we don't have as much time as we think

Ernie Branscomb said...

They also talked about the Mew Madrid earthquake that changed the course of the Mississippi River. WOW

Ben said...

At the Yurok Center of the World, on the Klamath, the place where Earthquake built his house is still visible, or it was when Waterman did his Yurok Geography. The Klamath was said to run upriver all the way to Wetchipek in 1700.
I lived on Scenic Drive south of Trinidad in the 80s. The cliff down to the road exposed layer after layer of river rock and a layer of clayish stuff near the top. Geology classes from HSU would come to look at it and I learned that each layer was an uplift from an earthquake and that the stuff near the top was the floor of an old lagoon. This had to be 200 feet above sea level, with an earthquake about every five feet.
The old timers used to tell me this country is trying to become a beach, by which they meant erosion in soft rock. Looking at that cliff, I realized that earthquakes are winning that battle.

ButterflyDice said...

I took that class at HSU & CR! It was an awesome class.