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Earth Science

Cape Verde Boulders Indicate Massive Tsunami 73,000 Years Ago 54

Posted by timothy from the or-the-egyptians dept.
TaleSlinger writes: Researchers from University of Bristol, UK found that boulders strewn 200m above sea level on Cape Verde, off the west coast of Africa, were ripped from cliffs below and washed up there by a tsunami between 170m and 270m (550-850ft). Researchers at Columbia University's Lamont-Doherty Earth Observatory dated the tsunami at 73,000 years ago. It's interesting that this is about the same time as the Mt. Toba Eruption and about the same time humans nearly became extinct.
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Cape Verde Boulders Indicate Massive Tsunami 73,000 Years Ago More

Cape Verde Boulders Indicate Massive Tsunami 73,000 Years Ago

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  • Say what? (Score:3)

    by djupedal ( 584558 ) on Saturday October 03, 2015 @01:47PM (#50652069)
    >and about the same time humans nearly became extinct.

    Can't be - there's at least one living right across the street.

  • Ignore the "humans almost went extinct" bit (Score:5, Informative)

    by 93 Escort Wagon ( 326346 ) on Saturday October 03, 2015 @02:12PM (#50652209)

    That's not from the Nature letter; apparently that's some off-the-wall addition from the submitter.

    Since the submitter hasn't figured this out... This was a localized mega-tsunami. An enormous volcanic-induced landslide caused a huge wave to hit a nearby island. Just like other mega-tsunamis that are known to have occurred in Hawaii and Alaska. The scientists aren't talking about some global catastrophe - it would've sucked to be on that other nearby island, though.

    • Re:Ignore the "humans almost went extinct" bit (Score:5, Informative)

      by Anonymous Coward on Saturday October 03, 2015 @02:22PM (#50652255)

      The potential for extinction obviously wasn't due solely to a tsunami. What is being referred to is this [ox.ac.uk]:

      Toba had erupted a number of times previously (one of these, about 840,000 years ago, was itself a super-eruption). What was significant about the event 74,000 years ago was the coincidence that an important period in human evolution was occurring at the same time. The Earth was already inhabited by a number of species closely related to us, such as Homo neanderthalensis (the Neanderthals) in Europe, and Homo erectus and Homo floresiensis (sometimes called the ‘hobbits’) in southeast Asia. All of these survived Toba, but some archaeologists have claimed that almost all the anatomically modern humans (our direct ancestors) were killed by the environmental effects the volcano caused, with the remaining people surviving in refuges in Africa. This scenario is based on data from genetics, and because it suggests that people were narrowed down from many to very few numbers, it is known as a genetic ‘bottleneck’.

    • Re: (Score:2)

      by PPH ( 736903 )

      This was a localized mega-tsunami. An enormous volcanic-induced landslide caused a huge wave to hit a nearby island.

      Volcano in Indonesia (Indian Ocean) causes a tsunami in West Africa (Atlantic Ocean). I'd call that a bit more than localized.

      Most homo-whatever species were living in Africa and many lived near the coastlines. The combination of an immediate wipe-out plus an ensuing volcanic winter probably did put a major stress on our ancestors.

      • Re: (Score:2)

        by Rei ( 128717 )

        From the article:

        Such tsunamis may not have the same long-distance range as those that originate from underwater earthquakes, such as the 2004 tsunami in southeast Asia that travelled thousands of kilometres from where the seafloor ruptured.

        The article does not say that a volcano in Indonesia caused a tsunami in West Africa. Please read it.

    • I guess your post is a troll, but I will provide some context anyway

      The magnitude 9.0 earthquake off Japan in 2011, the biggest to hit the nation in recorded history, generated a tsunami that was up to 40 m high in a few restricted areas along the coast of Japan itself, but less than 3 m everywhere else the waves reached. A tsunami wave from Toba, North Sumatra would need to travel across the Indian Ocean, around South Africa and up almost the entire South Atlantic ocean into the North Atlantic to hit Cape

    • That's not from the Nature letter; apparently that's some off-the-wall addition from the submitter.

      There is a coincidence of timing. However, given that previous estimates for this particular sector collapse (see my comment elsewhere for the dozens of other "recent, geologically" Atlantic sector collapses) were between 50 and 150 thousand years ago, it is little more than coincidence.

      If there were a tight human population bottleneck (as opposed to a more drawn out but less severe one, with comparable cumu

  • Imagine living near a beach and seeing an 800 ft. wave coming at you. The fear would have been awful for a few seconds before you were slammed down under tons of water.

    • ! 800 foot wave? You don't need to be near the beach to get hit by that. For instance, that would pretty much wipe out Holland.

  • When I was taking a volcanology holiday a couple of years ago on the Canary Islands, the count of recognised deposits from mega-landslips around the island group was 23. Many more were unrecognised, probably, due to having been overlaid by more recent landslips. The period during which these were deposited was probably only 10 million years, for an event every half million or so years, and each would probably have had significant effects between Brazil, Newfoundland, Britain and Morocco.

    The Cape Verde isla

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