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Niwa observes underwater volcano changes
New
Zealand scientists investigating an active undersea volcano that
erupted three months ago have discovered significant changes to the
seafloor.
27
October, 2012
Niwa
research ship Tangaroa has mapped the Kermadec volcano that erupted
800km northeast of Tauranga on July 19, producing a pumice raft the
size of Canterbury.
The
eruption was strong enough to breach the ocean surface from a depth
of 1100 metres. It was captured by a Nasa satellite, and a Royal New
Zealand Air Force Orion patrol spotted the pumice on their way back
home from Samoa.
Niwa's
volcanologist Dr Richard Wysoczanski, who is leading the 23-day
expedition, said there had been volcanic activity every year for the
past decade, but this was the largest by far.
"It
is a substantial eruption. Had it occurred on land in New Zealand, it
would have been a bit of a disaster."
The
volcanic caldera, which is like Lake Taupo, known to produce large
and violent eruptions, spewed up to 10,000 more material than the Mt
Tongariro eruption on August 6, he said.
It
was mapped in 2002, showing a 1km-high undersea mountain with a 5km
wide, 800-metre deep central crater.
This
week, scientists found a new volcanic cone which has formed on the
edge of the volcano, towering 240 metres above the crater rim.
They
also found one side of the caldera wall is bulging in towards the
volcano's centre, indicating where an eruption may occur in the
future or it may lead to an undersea avalanche.
Several
cubic kilometres of new material has also been added to the volcano,
with large volumes of freshly erupted pumice accumulating on the
caldera floor, raising it by up to 10 metres.
"We
couldn't find any biology on the floor and the immediate vicinity has
been completely wiped out," Wysoczanski said.
Fresh
volcanic rocks, up to beach ball size, will be brought back to Niwa
for analysis.
Tangaroa
embarked on the expedition to study the volcanic chain that stretches
for 1000km north from Bay of Plenty. It is due back in Wellington on
November 1.
Increase in seismicity around Salton Sea region linked to rifting of California
16
October, 2012
Earthquake
swarms and a region-wide rotten egg smell recently reminded Southern
California residents they live next to an active volcano field, tiny
though it may be.
At
the time, scientists said the phenomena did not reflect changes in
the magma chamber below the Salton Sea. But now, researchers may need
to revise estimates of the potential hazard posed by the Salton
Buttes — five volcanoes at the lake’s southern tip.
The
buttes last erupted between 940 and 0 B.C., not 30,000 years ago, as
previously thought, a new study detailed online Oct. 15 in the
journal Geology reports.
The new age — which makes these some of California’s youngest
volcanoes — pushes the volcanic quintuplets into active status. The
California Volcano Observatory, launched in February by the U.S.
Geological Survey (USGS), already lists the area as a high threat for
future blasts.
“The
USGS is starting to monitor all potentially active volcanoes in
California, which includes the Salton Buttes,” said study author
Axel Schmitt, a geochronologist at the University of California, Los
Angeles. “With our results, I think this will further enhance the
need to look into the system,” Schmitt told OurAmazingPlanet.
The
buttes exist because California is tearing apart, forming new oceanic
crust as magma wells up from below.
The
sinking Salton Trough is the landward extension of the Gulf of
California, and marks the boundary between the Pacific and North
America tectonic plates.
In
August, an earthquake swarm shook the nearby town of Brawley. The
USGS attributed the temblors to faults in the Brawley Seismic Zone.
In September, a sulfurous stench emanated from the Salton Sea and
wafted across the Inland Empire. The odor was tentatively linked to a
fish die-off, but could also have been caused by volcanic gases,
Stock said.
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