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Ice Volcanoes
Fri Mar 26, 2004
Listen in RealAudio 
Ice volcanoes can form during winter on the Great Lakes. They are not lava-spewing mountains
of ice, but water-spouting ice cones. Hi, I'm Bryan Yeaton for The Weather Notebook.
As winter ice begins to build along the shores of large lakes such as Lake Superior, it is
jostled, broken, and shifted by the winds and wave motions on the waters. When winds blow
onshore, they can build an ice shelf, a jumble of ice chunks that anchors on the shore but
extends some distance back into the water. Amongst the numerous ice blocks comprising a shelf,
many open tunnels lead back to the lake waters.
To build a good ice volcano cone, the surface air temperature must be several degrees below
freezing and lake waves should be several feet high and breaking onshore. As the waves strike
the edge of the ice shelf, pulses of wave energy flow beneath the ice. Upon reaching the open
end of a tunnel, the wave forces water to erupt out through the ice. If the hole has been
covered with snow, the eruption may spray snow outward like a volcanic gas cloud.
As the ejected water falls back onto the ice, it quickly freezes and begins the formation of
an ice cone, a process very similar to the building of a lava cone surrounding a geologic
volcanic vent. A study of ice volcanoes on Lake Superior's southern shore by students from
Michigan Tech measured ice cones ranging from three to 25 feet in height.
Like rock volcanoes, ice volcano vents can heal over and become dormant during periods of low
wave action. They lie in wait for a strong wave surge to awaken them back to explosive
activity.
Thanks to our contributing writer, Keith Heidorn. Thanks also to Subaru and the National
Science Foundation.
Today's Links
Ice Volcanoes of Lake Superior\'s South Shore
http://www.geo.mtu.edu/volcanoes/ice/
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