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7 December, 2001
Weather report: We are "hut-bound" today. Woke up to 30 knot winds and
temperatures of 30 deegrees below zero. I had to plow my way out of my
tent in the morning. Visibility is very low (sometimes less than 10
meters).
I had intended to begin a series of journal entries that explained how
this team is going about understanding the mysteries of a volcano, when I
was interrupted yesterday by a first-time trip to the summit. I would
like to begin this first facet of inquiry by considering the idea of
simply (and not so simply) LOOKING at something. It is important to
remember that any sense employed to understand a new thing is useful
largely by its comparison to things already known. So, to a person who has
never studied geology, let alone vulcanology, the first sight of Mt. Erebus
might indeed inspire a bit of fear--if the only thing that the viewer has
to relate to this vision is the death and destruction brought about by
volcanoes of lore, and some recent ones as well. To a vulcanologist,
perhaps the first clue to the nature of a volcano is its shape. This can
obviously be determined whether it is active or not. The shape, in turn,
is largely determined by the type of material that is being expelled by
the volcano. I'll leave it to the reader, if interested, to investigate
the classification of volcanoes by these parameters.
It helps immensely to look at a volcano with the help of a trained eye.
Much as a physician sees things in a patient that even a parent might not
see, a geologist can explain what a person sees and shed real light on the
origins of the scenery. Mt. Erebus has a "caldera" (big) area of former
activity, and a relatively small crater. I emphasize the word
"relatively" because at first sight the crater is huge. Calderas, on the
other hand, can be many kilometers in diameter. Mt. Erebus has erupted in
a major way several times in goelogic history. It has erupted dangerously
(but not on a gargantuan scale) twice in recorded human history--most
recently in 1984. In that year the "Upper Erebus Hut" was abandoned, and
the "Lower Erebus Hut" (LEH) site selected.
Another readily visible thing to see is the rock that surrounds the
volcano. It makes such an impression on the observer both in its content
and physical properties. I will describe this briefly, as the minerology
of Erebus' rock as it sits on the ground is not part of this study. Mt.
Erebus is unique in that it is the only volcano in the world currently
producing lava that is phonolitic in nature. The name of the rock (when
it hardens) is anorthoclase phonolite. The phonolite portion is brittle
and weathers quickly. The anorthoclase feldspar within it is more hardy,
and crystalizes out of the magma to present itself as inclusions in the
rock. Because the crystals are more durable than the phonolite, we walk
across fields of these crystals freed from the degraded bombs that were
hurled >from Mt. Erebus. Another feature of the rock is its glassy
composition. This can be seen through the microscope when viewing the
ash, "Peles Hair" (see entry of 12/2), and the interior of the bombs that
lie on the slopes. I will dissect one of these bombs at my next
opportunity and photograph the interior.
One of the main research tools employed during this field season to
increase our ability to see the volcano is the repair, improvement, and
maintenance of a constant, real-time camera that looks into the crater at
the currently convecting lava lake. It is powered by a windmill located
on the slope about 200 feet below the crater. We can sit in the hut and
look up at a monitor to see if there is any interesting activity. If
there is an eruption (we're constantly waiting for this) the time on the
videotape can be correlated with the other senses being employed by the
team. For example, what did the seismologists and the GPS scientists FEEL
when this visible eruption occurred? What did the scientist studying the
acoustical properties of the volcano HEAR? And what did the people
analyzing the chemical composition of the gases SMELL with their
complicated equipment? Looking is an important tool. If you would like to
see clips of movies that have captured small eruptions, please visit the
Mt. Erebus Volcano Observatory Homepage (easy to find).
A side note: We had visitors today. A team from the "Exploratorium, which
is a cool museum in San Francisco, came to the LEH to have a live
broadcast (a telephone conversation, acutally) with students visiting the
museum at 11:00 this morning. They had sent video and pictures ahead, and
students were able to ask questions directly to members of the team. I
hope to do the same thing soon. Stay posted....
This is the camera perched at the rim of Mt. Erebus. It is fully functional, and we hope to have real-time video available on the web, on the Mt. Erebus Volcano Observatory Homepage. This will take some effort due to financial and bandwidth issues. See archived clips at the website.
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