An undersea
volcano situated 300 miles (480 km) off the coast of Oregon is thought
to be erupting after signs of magma were spotted near its deep sea vent.
Geologists predicted the volcano, called Axial Seamount, would erupt this year during a public lecture in September.
And
for more than a week the region has experienced thousands of tiny
earthquakes - a sign that magma is moving towards the surface.
Geologists predicted the volcano,
called Axial Seamount (pictured), would erupt this year during a public
lecture in September. And for more than a week the region has
experienced thousands of tiny earthquakes (activity pictured) - a sign
that magma is moving toward the surface
The
seafloor has also reportedly dropped by almost 8ft (2.4 metres),
additionally said to be a sign of magma being withdrawn from a reservoir
beneath the summit.
It is dubbed Axial Seamount due its location along the axis of an underwater mountain ridge.
The
earthquakes were first recorded by William Wilcock from the University
of Washington using instrumentation from the NSF-funded Ocean
Observatories Initiative.
And the forecast was made by geologists Bill Chadwick of
Oregon State University and Scott Nooner of the University of North
Carolina Wilmington during a lecture last year, followed by a blog post.
They
based their forecast on some of their previous research, funded by the
National Science Foundation (NSF) and the National Oceanic and
Atmospheric Administration (NOAA), which showed how the volcano inflates
and deflates like a balloon in a repeatable pattern as it responds to
magma being fed into the seamount.
'It
isn't clear yet whether the earthquakes and deflation at Axial are
related to a full-blown eruption, or if it is only a large intrusion of
magma that hasn't quite reached the surface,' said Professor Chadwick,
who works out of OSU's Hatfield Marine Science Center in Newport and is
affiliated with NOAA's Pacific Marine Environmental Laboratory.
Researchers know of two previous eruptions by the volcano, but those 1998 and 2011 eruptions
were detected months or years afterward.
Last year, researchers connected monitoring equipment to an
undersea cable that, for the first time, allowed them to gather
live data on the volcano, whose peak is about 4,900 feet (1,500
meters) below the ocean surface.
This cable has led to the volcano being dubbed 'wired'.
'The cable allows us to have more sensors and monitoring
instruments than ever before, and it's happening in real time,'
said Professor Chadwick.
In the past, researchers left battery-operated monitoring
stations in place for several years, but were able to analyse
the data only by retrieving those devices.
Pressure sensors detected that an eruption was underway on
April 23.
After monitoring hundreds then thousands of small
earthquakes each day near Axial Seamount, they detected more
than 8,000 tiny quakes over a 24-hour span on this day.
As midnight approached, pressure sensors detected the
seafloor dropping - a sign that magma was erupting - and the
swollen volcano was 'deflating like an emptying balloon'.
The earthquakes were recorded by
William Wilcock from the University of Washington and the forecast was
made by geologists Bill Chadwick of Oregon State University and Scott
Nooner of the University of North Carolina Wilmington last year. The
seafloor has also dropped by 8ft (2.4 metres) (Axial Seamount pictured)
Last year,
researchers connected monitoring equipment to an undersea cable that
allowed them to gather live data on the volcano (location marked), whose
peak is about 4,900 feet (1,500meters) below the ocean surface
In
total, the seafloor has dropped 8 feet (2.4 meters) in the past
week.
Though the eruption has slowed, the volcano still seemed to
be expelling magma as of last Friday, Professor Chadwick said, leaving his team wondering where the lava was going.
'We know it didn't erupt in the caldera, or crater, because
that's where most of our sensors are, and they all survived,' he said.
Temperature fluctuations and seismic readings are consistent
with an eruption north of the volcano's crater.
'But we
probably won't know until this summer, when we get out there
with a ship and are able to look around.'
The Juan de Fuca Ridge (pictured) is
part of an ocean ridge system situated 300 miles (480km) off the coast
of Oregon. Axial Seamount rises almost a 0.6 miles (one km) above this
ridge.
In any case, the researchers say, such an eruption is not a threat to coastal residents.
The earthquakes at Axial Seamount are small and the seafloor movements gradual and thus cannot cause a tsunami.
Axial
Seamount provides scientists with an ideal laboratory, not only because
of its close proximity to the Northwest coast, but for its unique
structure.
'Because
Axial is on very thin ocean crust, its 'plumbing system' is simpler
than at most volcanoes on land that are often complicated by other
factors related to having a thicker crust,' continued Professor
Chadwick.
'Thus Axial can give us insights into how volcano magma systems work - and how eruptions might be predicted.'
Geologists
are scheduled to go back to Axial in August to gather more data, but it
may be possible for other researchers to visit the seamount on an
expedition as early as May.
They hope to confirm the eruption and, if so, measure the volume of lava involved
No comments:
Post a Comment