Volcanoes are unremarkably divided into two sort , those that produce rivers of fervour that threaten only thegeneral vicinityand the ones whose volatile bang can dip the worldinto darknessand unleashenormous tsunami . However , a new study suggests the truth is more complex , and we should n’t get too comfortable about the first character .
The style of a vent ’s volcanic eruption is set by the composition of its magma . Basaltic magmas grow the lava rivers of Hawaii , while more silica - plenteous lava creates a Vesuvius or Krakatoa . Volcanologists ' assumption has been these magmas are fairly constant over time .
However , Dr Michael Stockof Trinity College Dublin led a team to inquire two of the volcano that formed two of the Galápagos islands , Wolf and Fernandina , both known for their basaltic lava flows .
Stock and co - authors report inNature Communicationsfinding a wide variety of chemical writing . Some lava , tephra , and nodule samples from these volcanoes look like they would be much more at home at Mount St Helens , Washington , site of a renowned volatile irruption in 1980 , than the shield volcanoes of the islands on which they were found .
As in the more famous Hawaiian example , the Galápagos island lie over aplumeof hot magma that has pierce the pelagic gall , and push mountains above the water line . The plate is moving over the plume , so old island make up the sites that were once directly above it .
Stock think liquids with higher silica contents get trap in chambers around a kilometer beneath the surface . Near a plumage ’s center basaltic magma rises so fast materials with other paper are launder out to the point we scarce discover them .
However , once they ’re only at the bound of a hot spot , the pace at which magma rushes up from below declines and may no longer deluge the contents of these chamber , making explosive eruptions potential .
“ This was really unexpected , ” Stock said in astatement . “ We start the discipline wanting to roll in the hay why these volcano were so dull and what process cause the erupt lava compositions to stay constant over foresighted timescales . Instead we found that they are n’t bore at all , they just obliterate these secret magmas under the ground . "
Wolf and Fernandina represent no threat , at least on human timescales – they still have plenteous amount of basaltic fabric reload them . The situation is different further from the plumage ’s meat in the Eastern Galápagos , however , where the volcano have much lower flux rates . There is a much greater danger that after 1000 of eld of basaltic lava production , these volcanoes will one day switch to something far more dangerous , and the same could apply to other volcanoes worldwide we presently see dependable .
