(dramatic music)
- [Narrator] Supervolcanoes
are the most violent
and complex class of volcanoes.
But despite their
destructive capabilities,
they can also make way for life renewed.
Around 20 supervolcanoes are
scattered across the planet.
They're usually characterized
as large depressions in the
ground, called calderas,
located above multiple
openings in the Earth's crust.
In terms of eruptions,
supervolcanoes explode
at a magnitude of eight,
the highest and most
violent classification
on the Volcanic Explosivity Index.
Supervolcanoes undergo a life
cycle of three major stages:
a surge of trapped magma, a
supereruption, and a resurgence.
The first stage of a
supervolcano's life cycle
involves a pocket of magma
trapped under the Earth's crust.
Called a hotspot, this magma
reservoir is fed by a pipeline
deep into Earth's molten interior.
It grows and builds pressure underground,
eventually causing the crust
above to be pushed upward.
The supervolcano Campi Flegrei
on the west coast of Italy
has pushed the ground up
several times over the past few decades.
At one point, within a
matter of only two years,
enough magma accumulated
to cause the ground
to swell up to six and a half feet.
The next stage of a
supervolcano's life cycle
is a supereruption.
At this point, the buildup of pressure
in a magma reservoir hits a
critical mass and then explodes,
sending over 1,000 cubic
kilometers of tephra,
or ash and rocky material, into the sky.
The most recent supereruption
occurred in New Zealand
approximately 26,000 years ago.
The supervolcano Taupo ejected
about 1,100 cubic kilometers
of tephra into the air,
enough material to constitute
nearly half a million
Great Pyramids of Giza.
After a supereruption,
a supervolcano undergoes
a stage called resurgence.
Having dispelled its contents,
a supervolcano's magma reservoir collapses
and forms a caldera.
The Yellowstone Caldera
in the United States
is currently in resurgence,
after a supereruption occurred
about 640,000 years ago.
In the time since,
freshwater collected in
the caldera to form a lake,
plants and wildlife returned
to reclaim the space,
and some of the world's largest
geothermal features emerged.
Supervolcanoes have created
unparalleled natural beauty,
all in the wake of some of the world's
most cataclysmic events.
