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TITLE: Submarine Volcanoes in Action


[Photo: Submarine Volcanoes]

Because spreading ridges are so deep and so remote, humans rarely witness volcanic eruptions along them. But the Juan de Fuca Ridge's proximity to oceanographic laboratories has enabled scientists to study its undersea volcanism in great detail. Since 1986, they have detected several eruptions.


 

  Photo: Pillow Lava  
  Cut Pillow Lava  
     
  Photo: Sea-Floor Basalt  
  Pillow Lava  

Magma that erupts on the sea floor is instantly enveloped by frigid ocean bottom water. The magma immediately adjacent the sea water freezes rapidly to glass, while interior portions cool more slowly to form glass studded with tiny crystals. Sea-floor eruptions commonly generate stacks of bulbous and tubular lava lobes that accumulate to look like a stack of pillows.


 


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Smithsonian National Museum of Natural History Department of Mineral Sciences website Credits