If Lava is over 1000c and it burns everything in its path why
doesn't it burn the volcano as well
Carole
Hi Carole,
We've answered this one before but perhaps not very clearly.
For the first part, lava doesn't burn everything in its path. Trees often
remain standing after lava flows have flowed around them. What happens is
that a semi-solid skin forms wherever lava is exposed to something cooler
than the lava (such as the air, the ground, or a tree). Even though
actual hot molten lava may contact the tree for an instant, the skin forms
in only a few seconds and starts to thicken. This skin helps to insulate
the tree from the high-temperature molten lava and lets it keep standing
(although it will probably die soon). Try dipping a chopstick into melted
wax and you will see that a layer of wax quickly forms against the
chopstick. This is analogous to the layer of lava against the tree.
As for the second part of your question, the answer is that lava is just
not hot enough to melt the solid version of itself. A basalt lava
flow will probably be flowing down a volcano made up of basalt. For a
basalt flow to easily melt solid basalt it has to be super-heated, and as
far as we have observed, lava flows are not super-heated. Instead they
have lost some of their initial heat along the way from the magma source
to the surface.
The only place where melting seems to occur is within lava tubes that flow
for long periods of time. When geologists regularly visit the same
skylight into an active lava tube (to collect samples of measure
temperatures) the often notice that the surface of the flowing lava gets
lower and lower as the weeks and months go on. If the eruption isn't
slowing down then one explanaiton for the surface dropping is that the
lava is eroding the bottom of the tube. Since lava is opaque and it is
really hard to determine the depth of flowing lava this downward erosion
has not been confirmed.
I hope this helps to answer your question.
Sincerely,
Scott Rowland
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