Fear of Juan de Fuca megathrust earthquake


The north-west coast of the U.S. could be devastated by a huge movement of undersea plates known as a ‘megathrust’ earthquake, scientists say. A review of the dangers posed by the Juan de Fuca plate released in the wake of the Japanese quake has raised fears that the Pacific seaboard could be similarly ravaged.

The horrifying possibilities have been brought to light by data researched by the Active Tectonics and Seafloor Mapping Laboratory at Oregon State University. And the results are shown in a documentary, Megaquake: The Hour That Shook Japan, which is set to go out on the Discovery Channel in the UK this weekend.


The huge March 11 earthquake that sparked the tsunami off the coast of Japan may have been a ‘megathrust’ quake and now researchers fear the Cascadia fault line 50 miles off the U.S. coast could rupture and cause a quake and subsequent tsunami. The average time along that fault between massive quakes above magnitude 8 is 240 years, said The Times, and the last ‘megaquake’ was just over 300 years ago.

‘Megathrusts’ are the world’s largest earthquakes, and happen in a ‘subduction zone’, a region where one of the earth’s tectonic plates is thrust under another. The last one involving Cascadia was estimated at magnitude 9 on the Richter scale, according to Natural Resources Canada.

The Juan de Fuca plate is being forced under the North America plate along the Cascadia fault and, as large parts of the plates are locked together, stress is being built up until an eventual breakage causes a massive earthquake.


Professor Chris Goldfinger, director of the Laboratory at Oregon State University, told the newspaper that their information showed an increase in pressure at the plates: ‘It’s loading a spring for a future earthquake, there’s no doubt about that.’

And geologist Jeffrey Park, director of the Yale Institute for Biospheric Studies, said in a recent – separate – article: ‘History tells us that more megathrust earthquakes could occur in the next decade, but we have no evidence that the recent rate of nearly one megathrust per year will persist for longer than that.’

Cascadia, which stretches from Vancouver island to northern California, has been dormant for over 300 years but scientists now believe there is a 45 per cent probability of an earthquake of an 8.0 magnitude or higher in the next 50 years. They add there is a 15 per cent chance of magnitude 9 or more.

Such a quake could produce a massive tsunami and engulf the Pacific Northwest coast, affecting Oregon, Washington state and Vancouver Island, according to The Times, with a tsunami with waves of up to 30metres high and potentially reaching Japan.

The threat is all the more serious as several cities in the north-west of the U.S. are not adequately prepared for the type of devastation a ‘megathrust’ quake could wreak.

An upgrade programme is currently underway to protect the settlements most at risk.

Skyscrapers built in Seattle before 1994 – prior to more stringent building regulations – would be liable to collapse and countless small coastal communities could be swept away due to flooding. Some 1,000 schools in Oregon are reportedly judged to have poor resistance to eruptions, but the refurbishment is not set to be completed until 2032.

However, experts are unable to be specific about when a quake could hit.

‘We don’t know how to tell you, “Hey, next week, you know, get out of town there’s going to be a big earthquake”,’ Tom Jordan, director of the Southern California Earthquake Centre, told The Times.

John McCloskey, Professor of Geophysics at the University, added: ‘The problem with using a recurrence timeline is that earthquakes can be more like buses, coming two or three at a time rather than regularly.

‘We need a vision of what the biggest quake is likely to be in a region and then protect against that.’ (DailyMail)

Oregon Coastal Atlas

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  1. 3 years later and the closer we come to a Mega Quake on Cascadia. I don’t have any predictions as to when or how severe it will be. The Watchers are here good and bad. Will they inform someone who can come forward and warn in time? That would save many lives if they have that ability to know.
    Folks, not to get too far off subject but I’d like to give a conclusion I’ve arrived at. My opinion only. Our country America has an Elite that are 400 years advanced. Yes I could say more but most would just write me off. Can they control our weather, quakes, Volcanoes etc., not sure. I just Pray they are working to help Humanity in our Future.

  2. I think the percentage is not precise. My senses are telling me soon! I have no rational for this but as some things we know in life are true I’m betting on being safe. Logic kicks in when the ring-of-fire shows its hand. If cascadia goes the San Andreas could go as well along with several Volcano’s north and south. recent activity in desert area of CA and in the Pacific Ocean points directly at disaster. If all these scenarios occur then we could witness the predicted sinking of the west coast states into the ocean. Might not have to wait till 2012.
    There are so many new exciting discoveries science just wasn’t prepared for happening yearly. Ancient sites being unearth, exponential knowledge, new technologies that will break all aspiration and expectations, and paranormal activity that surrounds us everyday. Earth must be a beacon for those who wish us harm and those who wish us well. Belief in God has increased and that is a good thing in my opinion. I mean who else could have made the Universe certainly not the “Big-Bang,’ that is preposterous.

  3. JAN G C VAN DE LINDE commented on The Watchers:

    Living on the SW part of Vancouver Island, the situation is pretty important to my wife and me. Our house is up the slope of a hill, about 100 ft above the high water line. The soil is partly earth and rock. To the NW is French Beach which would be washed away by a tsunami, to the NE the land slopes up. I have earthquake insurance.
    We are interested in new research and articles about the situation.

  4. Shawnte commented on The Watchers:

    Yes, there is going to be a megathrust Earthquake along the “Juan de Fuca” plate. Its epicenter will be near the underwater volcano. According to what I heard from a pastor, this quake would occur shortly after a hurricane hits California. Since the Japan tsunamis, if no hurricane or tropical storms with a clearly defined eye has hit California then there’s still time to prepare and plan eva

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