We always knew what it should look like underground. The tube idea
made little sense while a nice fat reservoir pretty well sets it up.
Now we are locating them.
Yet they are quite properly little more that natural curiosities that
give us pleasure as a reminder of natures real power.
It is all good
Old Faithful's
underground cavern discovered
Tourists watch the
'Old Faithful' geyser which erupts on average every 90 minutes in the
Yellowstone National Park, Wyoming on June 1, 2011.
By Becky
Oskin, OurAmazingPlanet
Old Faithful's
underground plumbing looks more like a bagpipe than a flute, a new
study of the Yellowstone National Park geyser finds.
A big chamber sits
about 50 feet underground, located southwest of Old Faithful,
researchers report in a study published online March 30 in the
journal Geophysical Research Letters. The exact size can't be
determined, but they estimate the egg-shaped void is at least 50 feet
tall and 60 feet wide. The cavern connects to a pipe angled about 24
degrees that feeds Old Faithful's maw.
Tiny tremors extracted
from seismic records collected in the 1990s revealed the shape of the
cavern and geyser conduit. Popping gas bubbles create the tremors.
Not only do the tremors map the shape of underground spaces, they can
also track water. For the first time, scientists have a clear view of
how Old Faithful works underground.
"We're able to
locate with one- to two-meter precision the place where the
boiling occurs," said Jean Vandemeulebrouck, a geophysicist
at the University of Savoie in France. "We can see the water
rising in the conduit."
Old Faithful earned
its name for its regular eruptions, which average every 92 minutes.
Just after an
eruption, there's a 15-minute recharge period with low water levels.
Then for about 50 minutes, water levels rise and seismic
activity increases. The chamber never empties, but as steam bubbles
fill the chamber, they can oscillate water in the conduit, eventually
leading to a violent steam explosion. The bubble trap is what helps
Old Faithful splash with smaller eruptions before fully blowing its
top.
The research is
another nail in the coffin for the long-standing idea that big
geysers erupt from long, narrow tubes. Earlier this year, researchers
working in Kamchatka's Valley of the Geysers showed the Russian
geysers also erupted from conduits fed by caverns. As with Old
Faithful, the geysers explode because of underground bubble traps.
Geysers are rare
features — only about 1,000 exist around the world. To form a
geyser, there must be abundant groundwater, a volcanic heat source
to warm the water, open spaces so the water can escape and a way to
trap bubbles.
Vandemeulebrouck is
now collaborating with the U.S. Geological Survey to study another
Yellowstone National Park geyser, called Lone Star. Their preliminary
results are similar to Old Faithful, he said.
"I think this
oscillating system is quite common in geysers," Vandemeulebrouck
told OurAmazingPlanet.
No comments:
Post a Comment