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Santorini eruption much larger than originally believed

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  • Robert M Whiting
    From Jack Sasson via the agade list: [Please note that this is a press release, not a news story or a scientific publication; treat its information
    Message 1 of 1 , Aug 31, 2006
      From Jack Sasson via the agade list:
      [Please note that this is a press release, not a news story or a
      scientific publication; treat its information accordingly.]

      >From <http://www.uri.edu/news/releases/?id=3654>:
      =========================================

      Department of Communications/News Bureau
      Division of University Advancement
      Alumni Center, 73 Upper College Road, Kingston, Rhode Island 02881
      Phone: 401-874-2116 / Fax: 401-874-7872

      Santorini eruption much larger than originally believed;

      Media Contact: Todd McLeish, 401-874-7892

      Santorini eruption much larger than originally believed;
      likely had significant impact on civilization

      URI, Greek scientists find hydrothermal vent system nearby

      KINGSTON, R.I. -- August 23, 2006 -- An international team of
      scientists has found that the second largest volcanic eruption in
      human history, the massive Bronze Age eruption of Thera in Greece,
      was much larger and more widespread than previously believed.

      During research expeditions in April and June, the scientists from
      the University of Rhode Island and the Hellenic Center for Marine
      Research found deposits of volcanic pumice and ash 10 to 80 meters
      thick extending out 20 to 30 kilometers in all directions from the
      Greek island of Santorini.

      "These deposits have changed our thinking about the total volume of
      erupted material from the Minoan eruption," said URI volcanologist
      Haraldur Sigurdsson.

      In 1991 Sigurdsson and his URI colleague Steven Carey had estimated
      that 39 cubic kilometers of magma and rock had erupted from the
      volcano around 1600 B.C., based on fallout they observed on land.
      The new evidence of the marine deposits resulted in an upward
      adjustment in their estimate to about 60 cubic kilometers. (The
      eruption of Mount Tambora in Indonesia in 1815 is the largest known
      volcanic eruption, with approximately 100 cubic kilometers of
      material ejected.)

      An eruption of this size likely had far-reaching impacts on the
      environment and civilizations in the region. The much-smaller
      Krakatau eruption of 1883 in Indonesia created a 100-foot-high
      tsunami that killed 36,000 people, as well as pyroclastic flows
      that traveled 40 kilometers across the surface of the seas killing
      1,000 people on nearby islands. The Thera eruption would likely
      have generated an even larger tsunami and pyroclastic flows that
      traveled much farther over the surface of the sea.

      "Given what we know about Krakatau, the effects of the Thera
      eruption would have been quite dramatic," said Carey, a co-leader
      of this year's expeditions. "The area affected would have been very
      widespread, with much greater impacts on the people living there
      than we had considered before.

      Thera has erupted numerous times over the last 400,000 years, four
      of which were of such magnitude that the island collapsed and
      craters were formed. Some scientists believe the massive eruption
      3,600 years ago was responsible for the disappearance of the Minoan
      culture on nearby Crete. Others link the eruption to the
      disappearance of the legendary island of Atlantis.

      While investigating the seafloor around Santorini, the scientists
      explored the submarine crater of the Kolumbo volcano, just 5
      kilometers from Thera and part of the same volcanic complex, and
      discovered an extensive field of previously unknown hydrothermal
      vents. Using remotely operated vehicles from the Institute for
      Exploration, the scientists recorded gases and fluids flowing from
      the vents at temperatures as high as 220 degrees Centigrade.

      "Most of the known vents around the world have been found on the
      mid-ocean ridges in very deep water and in areas where there are
      geologic plate separations," Sigurdsson explained. "The Kolumbo and
      Santorini volcanoes are in shallow water at plate convergences, the
      only place besides Japan where high-temperature vents have been
      found in these conditions."

      "The high temperature of the vents tells us that the volcano is
      alive and healthy and there is magma near the surface," added Carey.

      The scientists said that, in addition to fluids and gases, the
      vents are emitting large quantities of metals, including silver,
      which precipitate out to form chimneys on the crater floor up to 10
      feet tall and 2 to 4 feet wide. The floor of the crater is covered
      in a layer of red and orange mats of bacteria 2 to 3 inches thick
      that live on the nutrients in the vent fluids. Bacteria also cover
      the vent chimneys, and 4- to 5-inch long, hair-like bacterial
      filaments extend from the chimneys making them "look like hairy
      beasts, like woolly mammoths," according to Sigurdsson.

      The expedition was part of a longer research cruise led by National
      Geographic Explorer-in-Residence Robert Ballard, a URI oceanography
      professor and president of the Institute for Exploration, which
      included a search for Bronze Age shipwrecks in the Black Sea and a
      survey of the seafloor in the Sea of Crete. Additional details can
      be found at www.uri.edu/endeavor/thera or
      www.oceanexplorer.noaa.gov/explorations/06blacksea/.

      The research expeditions were funded in large part by the National
      Science Foundation, with additional support from the NOAA Office of
      Ocean Exploration, the Rhode Island Endeavor Program, the Institute
      for Exploration, and the National Geographic Society. The April
      expedition was conducted aboard the Greek research vessel Aegaeo,
      while the June cruise was aboard the URI vessel Endeavor.

      Live video of the June expedition was broadcast over the internet
      24 hours a day by Immersion Presents, which also broadcast four,
      30-minute live programs each day to museums, school districts,
      science centers and Boys and Girls Clubs featuring Sigurdsson,
      Carey and Ballard.
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