picture of the day
The Tharsis volcanoes superimposed on a
map of the United States. Credit: NASA The Red Planet # 10
Oct 24, 2007
The Tharsis Montes Volcanoes
Volcanoes on Mars should not be found in chains
similar to those on Earth since no crustal plate movement
exists there. Could electricity be a factor?
Scientists from the
University of Arizona and the Goddard Space Flight Institute
recently announced that the volcanoes located in the
Tharsis Montes region on Mars might not be extinct after
all. Because the four gigantic craters are near one another
and three of them run in a chain, scientists thought that
they must have been created in the same way that standard
theories explain crater chains.
According to the
lead author of a paper appearing in Geophysical Research,
Jacob Bleacher, that might not be how it happens on Mars.
Pavonis Mons and
Arsia Mons could have a moving column of magma beneath
Earth form when the plates that make up the Earth's crust
move over upwelling magma plumes, according to standard
theories. Rising magma naturally seeks out the weakest
fractures that allow it to erupt onto the surface, or under
the ocean. Island chains may appear if enough lava deposits
build up and create steep-sided mountains whose tops break
however, there is no evidence that the crust moves. No plate
boundaries exist so there should be no line of volcanoes
similar to the Hawaiian Islands, for instance. In order to
explain the Tharsis anomaly, Bleacher and his colleagues
have postulated that the plume of magma is what moved rather
than the crust.
"We thought we
could take what we learned about lava flow features on
Hawaiian volcanoes and apply it to Martian volcanoes to
reveal their history. The problem was that until recently,
there were no photos with sufficient detail over large
surface areas to reveal these features on Martian volcanoes.
We finally have pictures with enough detail from the latest
missions to Mars, including NASA's Mars Odyssey and Mars
Global Surveyor, and the European Space Agency's Mars
Thunderbolts Picture of the Day articles about the
Martian volcanoes, Olympus Mons in particular, we
theorized that the shape of the escarpments and the
surrounding topography indicates that they could have been
made by enormous
plasma discharges that impacted the planet. The force of
the electric current raised the giant mounds and carved out
their distinctive calderas.
Wal Thornhill points out:
25 kilometres high, is NOT the highest volcano in the Solar
System. It is a giant raised electrical blister with
characteristic superimposed circular craters at the summit.
It is the kind of blister seen on metal lightning arrestor
caps after a strike."
currents of such magnitude influenced the geography of Mars,
could they have done something similar on Earth? Is it the
theory of plate tectonics and its relationship to volcanism
on our planet that should be reconsidered, rather than
inventing a new theory because new observations do not
support the old one?
Stephen Smith from an idea
submitted by Michael Goodspeed
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