Yellowstone Caldera : The Biggest Volcanic Eruption Ever Awaits Mankind
Δημοσιεύτηκε στις 12 Ιαν 2014
Yellowstone National Park lies on top of a magma chamber that is 35-miles wide, waiting to erupt.
The
Yellowstone Caldera is the volcanic caldera and supervolcano located in
Yellowstone National Park in the United States, sometimes referred to
as the Yellowstone Supervolcano. The caldera is located in the northwest
corner of Wyoming, in which the vast majority of the park is contained.
The major features of the caldera measure about 34 by 45 miles (55 by
72 km). The caldera formed during the last of three supereruptions over
the past 2.1 million years. First came the Huckleberry Ridge eruption
2.1 million years ago, which created the Island Park Caldera and the
Huckleberry Ridge Tuff. Next came the Mesa Falls eruption 1.3 million
years ago, which created the Henry's Fork Caldera and the Mesa Falls
Tuff. Finally came the Lava Creek eruption 640,000 years ago, which
created the Yellowstone Caldera and the Lava Creek Tuff.
The last
full-scale eruption of the Yellowstone Supervolcano, the Lava Creek
eruption which happened nearly 640,000 years ago, ejected approximately
240 cubic miles (1,000 km3) of rock, dust and volcanic ash into the sky.
Geologists
are closely monitoring the rise and fall of the Yellowstone Plateau,
which measures on average 0.6 inches (1.5 cm) yearly, as an indication
of changes in magma chamber pressure.
The upward movement of the
Yellowstone caldera floor between 2004 and 2008 — almost 3 inches (7.6
cm) each year — was more than three times greater than ever observed
since such measurements began in 1923. From mid-summer 2004 through
mid-summer 2008, the land surface within the caldera moved upward as
much as 8 inches (20 cm) at the White Lake GPS station. By the end of
2009, the uplift had slowed significantly and appeared to have stopped.
In January 2010, the USGS stated that "uplift of the Yellowstone Caldera
has slowed significantly" and that uplift continues but at a slower
pace. The U.S. Geological Survey, University of Utah and National Park
Service scientists with the Yellowstone Volcano Observatory maintain
that they "see no evidence that another such cataclysmic eruption will
occur at Yellowstone in the foreseeable future. Recurrence intervals of
these events are neither regular nor predictable." This conclusion was
reiterated in December 2013 in the aftermath of the publication of a
study by University of Utah scientists finding that the "size of the
magma body beneath Yellowstone is significantly larger than had been
thought." The Yellowstone Volcano Observatory issued a statement on its
website stating,
" Although fascinating, the new findings do not
imply increased geologic hazards at Yellowstone, and certainly do not
increase the chances of a 'supereruption' in the near future. Contrary
to some media reports, Yellowstone is not 'overdue' for a supereruption.
"
Other media reports were more hyperbolic in their coverage.
A
study published in GSA Today identified three fault zones that future
eruptions are most likely to be centered on. Two of those areas are
associated with lava flows aged 174,000--70,000 years, and the third
area is a focus of present-day seismicity.
The
Yellowstone Caldera is the volcanic caldera and supervolcano located in
Yellowstone National Park in the United States, sometimes referred to
as the Yellowstone Supervolcano. The caldera is located in the northwest
corner of Wyoming, in which the vast majority of the park is contained.
The major features of the caldera measure about 34 by 45 miles (55 by
72 km). The caldera formed during the last of three supereruptions over
the past 2.1 million years. First came the Huckleberry Ridge eruption
2.1 million years ago, which created the Island Park Caldera and the
Huckleberry Ridge Tuff. Next came the Mesa Falls eruption 1.3 million
years ago, which created the Henry's Fork Caldera and the Mesa Falls
Tuff. Finally came the Lava Creek eruption 640,000 years ago, which
created the Yellowstone Caldera and the Lava Creek Tuff.
The last
full-scale eruption of the Yellowstone Supervolcano, the Lava Creek
eruption which happened nearly 640,000 years ago, ejected approximately
240 cubic miles (1,000 km3) of rock, dust and volcanic ash into the sky.
Geologists
are closely monitoring the rise and fall of the Yellowstone Plateau,
which measures on average 0.6 inches (1.5 cm) yearly, as an indication
of changes in magma chamber pressure.
The upward movement of the
Yellowstone caldera floor between 2004 and 2008 — almost 3 inches (7.6
cm) each year — was more than three times greater than ever observed
since such measurements began in 1923. From mid-summer 2004 through
mid-summer 2008, the land surface within the caldera moved upward as
much as 8 inches (20 cm) at the White Lake GPS station. By the end of
2009, the uplift had slowed significantly and appeared to have stopped.
In January 2010, the USGS stated that "uplift of the Yellowstone Caldera
has slowed significantly" and that uplift continues but at a slower
pace. The U.S. Geological Survey, University of Utah and National Park
Service scientists with the Yellowstone Volcano Observatory maintain
that they "see no evidence that another such cataclysmic eruption will
occur at Yellowstone in the foreseeable future. Recurrence intervals of
these events are neither regular nor predictable." This conclusion was
reiterated in December 2013 in the aftermath of the publication of a
study by University of Utah scientists finding that the "size of the
magma body beneath Yellowstone is significantly larger than had been
thought." The Yellowstone Volcano Observatory issued a statement on its
website stating,
" Although fascinating, the new findings do not
imply increased geologic hazards at Yellowstone, and certainly do not
increase the chances of a 'supereruption' in the near future. Contrary
to some media reports, Yellowstone is not 'overdue' for a supereruption.
"
Other media reports were more hyperbolic in their coverage.
A
study published in GSA Today identified three fault zones that future
eruptions are most likely to be centered on. Two of those areas are
associated with lava flows aged 174,000--70,000 years, and the third
area is a focus of present-day seismicity.
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