The massive volcanic dome is one of the
largest ever discovered. It is higher than the tallest building on
Earth. If this magmatic reservoir ever erupts, it’s going to be
apocalyptic.
October 2016 – CENTRAL ANDES – An
enormous dome has been discovered growing in the Central Andes above
the world’s largest active magma store. Found in the Altiplano-Puna
Plateau – the second highest plateau on the planet – the dome stretches
more than a kilometer high (3,280 feet), making it 172 meters taller
than the world’s tallest building in Dubai. Researchers say this massive
structure is the result of an injection of magma from below. “The dome
is the Earth’s response to having this huge low-density magma chamber
pumped into the crust,’ says one of the team, Noah Finnegan from the
University of California, Santa Cruz.
How did we all miss a massive dome of
Earth rising a kilometer above the surface? It just so happens to be
hidden within the Altiplano-Puna Plateau – a high, dry region, littered
with volcanoes, that extends for some 2,000 km along the Central Andes,
with an average height of 4,000 meters. The Central Andes constitutes
an even larger plateau, encompassing southern Ecuador, northwestern
Bolivia, and most of Peru. Together, the Central Andes, Southern Andes,
and Patagonia make up the Andes, the longest continental mountain range
in the world. So it’s easy to see how something could elude us in the
middle of all that. Back in 2014, the researchers used seismic imaging –
a tool that bounces sound waves off underground rock structures – to
reveal the enormous size and extent of the Altiplano-Puna magma body.
They found that this massive zone of
melted rock is a whopping 11 kilometers thick and 200 kilometers in
diameter – much larger than previous estimates. They’ve since gone back
to take a closer look at the internal structure of the Altiplano-Puna
plateau, and have identified a kilometer-high topographical dome, with
the dormant Uturuncu Volcano sitting right in the center of it. “People
had known about the magma body, but it had not been quantified that
well,” says one of the researchers, Jonathan Perkins. “In the new study,
we were able to show a tight spatial coupling between that magma body
and this big, kilometer-high dome.”
The dome is located within the
Altiplano-Puna Volcanic Complex, which sits in the southern part of the
Altiplano-Puna Plateau. Roughly 10 million years ago, this was one of
the most volcanically active places on the planet, and was shaped by a
series of super-volcano eruptions over several thousand years. Since the
1990s, satellite surveys have been conducted in the area, and have
shown consistent uplifting of the surface – in some places at a
surprisingly rapid rate. The Uturuncu volcano at the heart of the newly
discovered dome has been rising by about 1 centimeter every year, and
the team took it upon themselves to figure out why.
“We think the ongoing uplift is from
the magma body,” says Perkins. “The jury is still out on exactly what’s
causing it, but we don’t think it’s related to a super-volcano.” The
researchers suspect that activity in two tectonic plates in the region –
the South American continental plate and the Nazca oceanic plate – has
allowed magma to seep into the crust and feed the volcanoes. Meanwhile,
water is also being released by this activity, which changes the melting
temperature of the mantle rock in the lower Nazca oceanic plate,
prompting it to melt and rise into the overlapping South American
continental plate.
So the same process that once created our continents has been fueling the growth of this enormous dome. “This
is giving us a glimpse into the factory where continents get made,”
says Perkins. “These big magmatic systems form during periods called
magmatic flare-ups when lots of melt gets injected into Earth’s crust.
It’s analogous to the process that created the Sierra Nevada 90 million
years ago, but we’re seeing it now in real time.” –Science Alert
Planet X System Incoming: Birth Pangs (September 2016)
