Kyodo: M10 quake possible, says study — An hour of shaking — Tsunami lasting for several days

Published: December 15th, 2012 at 12:50 pm ET


Title: Magnitude 10 temblor could happen: study
Source: Kyodo
Date: Dec. 15, 2012
h/t Pu239

It is theoretically possible that the world could see a quake with a magnitude of around 10, a researcher at Tohoku University told the government’s Coordinating Committee for Earthquake Prediction, Japan. […]

“The estimate does not mean that a magnitude 10 quake will inevitably happen,” said Toru Matsuzawa, a professor at [Tohoku] university’s Research Center for Prediction of Earthquakes and Volcanic Eruptions. “If it happens, it would take place around once every 10,000 years.” […]

A magnitude 10 quake would likely cause ground motions for up to an hour, with tsunami hitting while the shaking was still going on, according to the research. Tsunami would continue for several days, causing damage to several Pacific Rim nations.

See also: [intlink id=”asahi-japan-should-be-prepared-for-possibility-of-m10-quake-days-of-tsunamis-only-1-magnitude-below-asteroid-strike-video” type=”post”]{{empty}}[/intlink]

Published: December 15th, 2012 at 12:50 pm ET


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21 comments to Kyodo: M10 quake possible, says study — An hour of shaking — Tsunami lasting for several days

  • weeman

    Anything is possible 10 on the richter scale is a extinction level event, but every 10000 years is stretching it, their would be more geological evidence.

    • Sickputer

      Bingo weeman. +311

      And there is a monster asteroid somewhere headed for earth. Don't know when or where…but sometime in the next 50 million years. *;-)

    • guezilla

      Minor point as it may be, I think it's probably worth realizing that the Richter scale hasn't actually been in use (except for a few holdouts) for decades. The article in question is clearly talking about Moment Magnitude Scale, hence the "Magnitude", the modern measurement.

      The ol Richter scale and the modern Moment Magnitude scale are usually in agreement to few tenths of units so in common speech there's very little difference. In this case there is an amusing aside, though – the Richter scale was so devised that the most powerful earthquake thought possible would measure 10 Richters. As always in science it's nice to have independent verification, but "The most powerful earthquake could be 10 Richters" is no news, hence neither is magnitude 10 either.

      The most powerful earthquake in modern times so it could be accurtely measured was Valdivia earthquake in Chile 1960 and was pegged at 9.5 magnitude. Other earthquakes to top 9 were Prince William Sound, Alaska 1964 and Sumatra, Indonesia 2004. In view of the evidence I would sumbmit that the view of magnitue 10 "if it happens" happening every 10.000 years is actually optimistic, even though 10M is still 3 times as big as 9.5M.

      • Radio VicFromOregon

        guezilla, good catch. And here along the Oregon coast there is evidence of mega quakes and tsunami's that occur regularly every 3000 years. We are just now at that mark give or take a decade. Tree rings and salt water inundation cinched it for the few researchers that most people thought were crazy with their notions. Many indigenous populations also talk about repeated quakes and tsunami's. Given the location of a major offshore fault, there is about a 1 to 10 minute delay from mega quake to tsunami. One deadly tsunami here clearly originated in Japan about 1000 years ago. And, far inland, Portland, itself, sits atop several large faults with liquefaction plains scattered everywhere. The Willamette River that runs through town empties into the Columbia, a major river that travels to the sea. There is evidence of salt water inundation from the coast up the Columbia and into the Willamette within recent geological time. Portland is over 75 miles over a mountain range from the coast, yet, salt water was able to travel that far back up the rivers from quakes off the coast.

        • moonshellblue moonshellblue

          I just read about a huge odd shaped underwater volcano that is capable of vast destruction.

        • guezilla

          By the way, as mentioned before, I'm too lazy to watch videos which may have one or two soundbites of interest etc. but I'm going to hazard a guess that what the study is talking about is M10 quake off Japan, in which case the 10.000 year figure might be closer too. As has been pointed out the 311 Tohoku earthquake was a different fault from the "big one" being expected from an active fault in Japan.

          It's worth noting that Richter scale was invented only in 1935, and seismometer first developed and installed on around 40 instruments in 1892. We thus have only around 100 years of seismic records of any usable quality. Any farther than that, and one has to study local legends and signs of ancient damage and try to guess from that.

          Talking of earthquake sizes is precarious at best, of course. The Richter scale attempts to measure amplitude of the shaking (100km from epicenter) on a logarithmic scale, so that an earthquake 1 Richter stronger has 10 times as large shaking amplitude associated with it. From this follows that 0.5 Richters more has 3.16 times higher amplitude (3.16 * 3.16 = 10).

          However, the ENERGY needed to create one Richter higher amplitude is generally about 31.6 times higher (5.62 times for half a magnitude). Moment Magnitude Scale attempts to close match to Richter scale, but attempts to measure the total energy released (mechanical work) via size of the earthquake rather than just amplitude of shaking at arbitrary point.

      • HoTaters HoTaters

        guezilla, can you please explain how a 0.5 difference in intensity would mean the earthquake is three times as strong? The Mercalli scale is linear, but am not clear on how it works at higher magnitudes. Thanks.

      • weeman

        No minor point, that is why I said richter scale, they never say what scale they are using and any good scientist or news article needs to state what scale they are referring to.
        The earthquakes you mention in Chile etc, are they not reported in the richter scale, I believe so?
        Vic you live in one of the most active geologic zones on earth, you are surrounded by mounts Rainier, Adams, Hood, Shasta,St. Helen's and the biggest Yellowstone a hot spots, I would be more concerned about the giant mud flows these mountains produce but there is no argument you are prone to tsunami, big ones.
        That's why I like the Canadian shield very stable, not that that would help if Yellowstone becomes active.

        • guezilla

          Moment Magnitue Scale has replace Richter scale since 1970's, and especially so for largest earthquakes. Because Richter scale measures amplitude, and any larger erthquakes have an amplitude that won't fit on any seismograph in existence, and because back-tracking the amplitude to what it would be 100km from the epicenter depends on direction and isn't anywhere exact. Thus largesr earthquakes are almost exclusively measured in Moment Magnitude Scale.

          The Moment Magnitude is propotional to (ie. multiplication of) the area that moves, the size of the movement and elasticity of the adjacent earth. Constants in the equation are chosen so that the numbers closely match Richter scale, with emhasis on medium size earthquakes. You could think of it as the length of the fault that slips times the distance it slips. There is no factor for duration of the earthquake, it may be fairly constant to the other factors but on the other hand in recent EQ's there's been some confusion as to whether they were one or several earthquakes.

          I actually rea the article, and it seems they're suggesting a magnitude 10 earthquake would result from several faults slipping at once. From the Moment Magnitude Scale this makes immediate sense, though it's worth nothing that on logarithmic scale doubling of an earthquake will increase its magnitude by 0.3.

          Quick index to base-10 logarithmic increases
          +0.3: *2
          +0.5: *3
          +0.6: *4
          +0.7: *5
          +0.8: *6
          +0.9: *8

          • weeman

            Thanks guezilla for taking the time to reply and your patience with me, I completely agree with you the magnitude scale is far superior to gauge large earthquakes and is far more accurate.
            I always thought the earthquakes in chile and Alaska were reported in the richter scale, I stand corrected. Be well.

  • AGreenRoad AGreenRoad

    Low Dose Radiation Dangers/Symptoms For Children And Adults

    Earthquakes generally cause spikes in radiation downwind..

    Why All Nuclear Power Plants Must Be Shut Down

  • dosdos dosdos

    Whatever happened to "bye bye California"? The "big one" will eventually happen. Only question is when.

  • stopnp stopnp

    Yeah. Things can happen in the future. They probably will too.

  • odylan

    Super earthquakes may be more common than we think.

    I reckon, for example, that Malta has seen a couple of great earthquakes of at least strength 10.0 on the Richter within the last circa 40,000 years. The island is lopsided having been heaved up on the south side, that is the side facing Africa, on at least two occasions. You can readily appreciate the enormous power that caused this uplift by standing on the edge of the island's famous Dingli Cliffs and considering how and why an ancient track approaching the cliffs at right angles suddenly appears to vanish into thin air at the cliff's edge but in fact continues in the same direction as before from a point on the sea bed directly below. This evidence can be easily seen in the clear Mediterranean waters.

    Clues of this nature are all around us.