How long does it usualy take for lava to reach the surface of the Earth?
Matt and Steven
Hi Matt and Steven,
I'm not sure anyone knows this one for sure. It depends on what volcanoes
you're thinking about. For example, in 1980 at Mt. St. Helens, the first
indication that magma (we call molten rock "magma" before it reaches the
surface and "lava" after) was moving into the volcano came in early April, and
the eruption took place in mid-May. Certainly the magma was moving up from
within the upper mantle of the Earth prior to early April, but exactly how far
it had to come and how long it took to get there we don't know.
On the other hand, there are volcanoes like Kilauea which has been pretty much
been erupting constantly since 1983. There must be an almost
continuously-open pathway from the source of the magma in the upper mantle to
the volcano, but again, I don't think anyone has a very good idea of how fast
the magma is traveling through this pathway.
Sorry I don't have a good answer for you, but perhaps you will some day
discover it.
Sincerely,
Scott Rowland, University of Hawaii
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