A massive volcanic explosion sends
A massive volcanic explosion sends

rock, lava and ash everywhere.
rock, lava and ash everywhere.

Fire and destruction are all around you.
Fire and destruction are all around you.

If only there were a simple trick
If only there were a simple trick

to stop an eruption.
to stop an eruption.

Like maybe plugging up
Like maybe plugging up

those magma mountains with
those magma mountains with

good old concrete.
good old concrete.

Concrete is the most used
Concrete is the most used

material in the world.
material in the world.

With 18 billion metric tonnes (20 billion tons)
With 18 billion metric tonnes (20 billion tons)

used every year,
used every year,

you encounter it everywhere.
you encounter it everywhere.

Even the Colosseum was constructed using concrete.
Even the Colosseum was constructed using concrete.

That was nearly 2,000 years ago,
That was nearly 2,000 years ago,

and it’s still around today.
and it’s still around today.

This incredible, durable material
This incredible, durable material

is made of gravel, water and a bit of cement.
is made of gravel, water and a bit of cement.

And it only gets stronger with time.
And it only gets stronger with time.

The strongest of concretes
The strongest of concretes

can withstand the pressure of Challenger Deep,
can withstand the pressure of Challenger Deep,

the deepest part of our oceans.
the deepest part of our oceans.

But would it withstand an erupting volcano?
But would it withstand an erupting volcano?

Or would it be like extra deadly Mentos and Coca-Cola?
Or would it be like extra deadly Mentos and Coca-Cola?

Volcanic eruptions involve a lot of heat and pressure.
Volcanic eruptions involve a lot of heat and pressure.

If we poured concrete into a hot volcanic mouth,
If we poured concrete into a hot volcanic mouth,

surely it would just melt, right?
surely it would just melt, right?

Well, not exactly.
Well, not exactly.

Concrete has a melting point of about 1,500 °C (2,700 °F).
Concrete has a melting point of about 1,500 °C (2,700 °F).

Even the hottest orange lava
Even the hottest orange lava

only reaches 871°C (1,600 °F).
only reaches 871°C (1,600 °F).

But just because it wouldn’t melt
But just because it wouldn’t melt

doesn’t mean it could work.
doesn’t mean it could work.

Volcanoes erupt when the internal pressure from the magma
Volcanoes erupt when the internal pressure from the magma

reaches the point where the ground covering it breaks apart.
reaches the point where the ground covering it breaks apart.

Eventually, it collapses,
Eventually, it collapses,

and the magma runs free.
and the magma runs free.

The greater the pressure difference
The greater the pressure difference

between the surface and the magma,
between the surface and the magma,

the more explosive the volcanic eruption.
the more explosive the volcanic eruption.

So, putting a concrete plug on a volcano
So, putting a concrete plug on a volcano

would be a dangerous addition.
would be a dangerous addition.

We would be forcing the pressure
We would be forcing the pressure

to build up below the ground.
to build up below the ground.

Much higher than it usually would.
Much higher than it usually would.

This would make the inevitable explosion
This would make the inevitable explosion

even more energetic.
even more energetic.

If the magma were unable to penetrate the concrete,
If the magma were unable to penetrate the concrete,

it would explode out of the volcano sides.
it would explode out of the volcano sides.

This is a Vulcanian eruption.
This is a Vulcanian eruption.

This happened in 1980,
This happened in 1980,

when Mount St. Helens erupted.
when Mount St. Helens erupted.

The pressure build-up was so massive
The pressure build-up was so massive

that one of the sides was bulging out into a dome.
that one of the sides was bulging out into a dome.

The pressure became so great that the dome broke,
The pressure became so great that the dome broke,

and the volcano erupted sideways.
and the volcano erupted sideways.

This powerful explosion
This powerful explosion

ejected material at a velocity of 350 m/s (1,150 ft/s).
ejected material at a velocity of 350 m/s (1,150 ft/s).

Dozens of people died.
Dozens of people died.

Our concrete strategy
Our concrete strategy

wouldn't only end up with a Vulcanian eruption.
wouldn't only end up with a Vulcanian eruption.

The concrete plug would burst out too.
The concrete plug would burst out too.

The dust from the concrete
The dust from the concrete

would lead to fatal lung diseases and cancer.
would lead to fatal lung diseases and cancer.

The lava flow from a natural eruption
The lava flow from a natural eruption

is usually slow and predictable.
is usually slow and predictable.

So maybe a better plan would be
So maybe a better plan would be

to use the concrete to divert the flow
to use the concrete to divert the flow

away from cities and towns.
away from cities and towns.

Like in 1983, when Mount Etna erupted in Italy.
Like in 1983, when Mount Etna erupted in Italy.

The lava flow threatened three towns.
The lava flow threatened three towns.

Barriers of rock and ash were created to divert it.
Barriers of rock and ash were created to divert it.

The first barrier stood at 18 m (59 ft),
The first barrier stood at 18 m (59 ft),

and it was quickly overrun.
and it was quickly overrun.

The second barrier kept the lava from traveling further west.
The second barrier kept the lava from traveling further west.

So we could use concrete to form barriers or walls
So we could use concrete to form barriers or walls

to protect towns and cities.
to protect towns and cities.

But you probably shouldn't throw a ton of concrete bricks
But you probably shouldn't throw a ton of concrete bricks

into the flow to see what happens.
into the flow to see what happens.

You might be better off trying something colder.
You might be better off trying something colder.

Like an iceberg.
Like an iceberg.

But that’s a story
But that’s a story

for another WHAT IF.
for another WHAT IF.