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Tsunami alert for the Western coast of North America.

Comments

  • Registered Users Posts: 1,695 ✭✭✭ hawkwing


    TSUNAMI MESSAGE NUMBER 2
    NWS PACIFIC TSUNAMI WARNING CENTER EWA BEACH HI
    1220 AM HST TUE JAN 23 2018

    TO - EMERGENCY MANAGEMENT IN THE STATE OF HAWAII

    SUBJECT - TSUNAMI WATCH SUPPLEMENT

    A TSUNAMI WATCH CONTINUES IN EFFECT FOR THE STATE OF HAWAII.

    AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

    ORIGIN TIME - 1132 PM HST 22 JAN 2018
    COORDINATES - 56.0 NORTH 149.2 WEST
    LOCATION - GULF OF ALASKA
    MAGNITUDE - 8.2 MOMENT

    EVALUATION

    BASED ON ALL AVAILABLE DATA A TSUNAMI MAY HAVE BEEN GENERATED BY
    THIS EARTHQUAKE THAT COULD BE DESTRUCTIVE ON COASTAL AREAS EVEN
    FAR FROM THE EPICENTER. AN INVESTIGATION IS UNDERWAY TO DETERMINE
    IF THERE IS A TSUNAMI THREAT TO HAWAII.

    IF TSUNAMI WAVES IMPACT HAWAII THE ESTIMATED EARLIEST ARRIVAL OF
    THE FIRST TSUNAMI WAVE IS

    0423 AM HST TUE 23 JAN 2018


  • Registered Users Posts: 28,289 ✭✭✭✭ vicwatson


    Thinks that's been revised to 7.9 magnitude


  • Moderators, Recreation & Hobbies Moderators, Sports Moderators Posts: 15,430 Mod ✭✭✭✭ Tabnabs


    DUOEX5SWsAAl0Hr.jpg


  • Registered Users Posts: 8,675 ✭✭✭ Say my name


    It seems that there might be no tsunamis after all.
    Warnings are still in place but the time has passed now that any effects would have shown up in Kodiak.
    Kodiak is near to the epicentre of the earthquake.


  • Registered Users Posts: 8,675 ✭✭✭ Say my name


    A scary warning to wake up to in the middle of the night none the less

    According to Twitter a lot of people slept through the warnings.


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  • Registered Users Posts: 13,185 ✭✭✭✭ M.T. Cranium


    News reports here state that most people heeded the tsunami warning sirens and went to higher ground (this would be mostly in outer coastal areas of Vancouver Island and further north), but after they arrived the tsunami alert was cancelled and nothing happened, so all good.


  • Registered Users Posts: 1,785 ✭✭✭ piuswal


    News reports here state that most people heeded the tsunami warning sirens and went to higher ground (this would be mostly in outer coastal areas of Vancouver Island and further north), but after they arrived the tsunami alert was cancelled and nothing happened, so all good.

    Any idea as to how many alerts have been issued since the system went into operation and how many were eventually validated?


  • Registered Users Posts: 13,185 ✭✭✭✭ M.T. Cranium


    No idea, will try to find out. I don't think they sound these sirens (in B.C.) very often, seems that it was automatic on receipt of earthquake in given location and magnitude, then later it was realized by earthquake analysts that it was of the wrong sort to create a tsunami but the cancellation was about the same time that the wave was supposed to arrive.

    We haven't had many large quakes that distant in recent years, the only test cases have been almost immediate local warnings that have generally been on such a short time cycle that people just ran for higher ground when they felt the shaking but those turned out to be too small in magnitude to create big tsunamis even where the quake was felt.

    There has not been anything very actionable here since a large tsunami with the March 1964 earthquake (believe that was 9.2) near Valdez AK, and that one did considerable damage on west coast of Vancouver Island with some drownings, hence the warning system.

    I think people out on the "outer" coast are very aware of these warning systems, but if one ever went off in the more sheltered inner coasts near bigger cities, I doubt that people would necessarily respond, in fact I don't even know what parts of the inner coast have that system in place. A quake in just the right spot in Puget Sound or the Strait of Juan de Fuca might cause a tsunami further inland but it has never happened in the two centuries of our recorded history, some archaeological indications that a big quake in Japan in 1700 sent a devastating tidal wave across the Pacific and did enormous damage to coastal native settlements.

    Generally speaking this whole region (BC, WA) is living in the expectation that we are long overdue for something large-scale, Mount Rainier going volcanic being the most significant worry, then a damaging earthquake off the west coast or in Puget Sound. We had a rather minor one in Feb 2002 that still did quite a bit of damage in Seattle, and they get 5-6 on Richter scale tremors all the time near the coast. I've felt two myself in the 22 years we lived there. But it's "tick tock" on the Big One.


  • Registered Users Posts: 25,881 ✭✭✭✭ Wanderer78


    Astonishing amount of aftershocks in the region, plate is very active


  • Registered Users Posts: 2,821 ✭✭✭ Pa ElGrande


    Something Shocking Happened in Florida After the Alaska Earthquake: Well Water Levels Changed
    https://weather.com/news/news/2018-01-24-alaska-earthquake-florida-wells-shaking
    Tuesday's 7.9 magnitude earthquake in the Gulf of Alaska sent vibrations through the earth that caused water to rise and fall in wells in Florida, thousands of miles away.

    Sensors near Fort Lauderdale and Madison, near the Georgia border, showed a minor change in water levels after the earthquake, according to the United States Geological Survey (USGS).

    A water level rise from 41.59 feet to 41.77 feet was recorded at the well near Madison before it returned to normal. At the well near Fort Lauderdale, the water level fell from 1.42 feet to 1.31 feet.

    Why did water levels in these wells some 3,800 miles away from the earthquake's epicenter change?

    Vibrations that move through the earth called seismic waves are the culprit. Seismic waves are depicted by the upward and downward lines on seismographs used to detect earthquakes around the world.

    "Water levels in wells respond to the seismic-wave induced expansion and contraction of the aquifer tapped by the well, in turn causing step or oscillatory fluid-pressure changes," the USGS says.

    source


    What Are Seismic Waves? - -> http://www.geo.mtu.edu/UPSeis/waves.html

    The response of well-aquifer systems to seismic waves - -> http://onlinelibrary.wiley.com/doi/10.1029/JZ070i016p03915/abstract

    Here is an example from a well in Virginia, note the spike on Jan 23


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