A massive volcanic explosion sends
rock, lava and ash everywhere.
Fire and destruction are all around you.
If only there were a simple trick
to stop an eruption.
Like maybe plugging up
those magma mountains with
good old concrete.
Concrete is the most used
material in the world.
With 18 billion metric tonnes (20 billion tons)
used every year,
you encounter it everywhere.
Even the Colosseum was constructed using concrete.
That was nearly 2,000 years ago,
and it’s still around today.
This incredible, durable material
is made of gravel, water and a bit of cement.
And it only gets stronger with time.
The strongest of concretes
can withstand the pressure of Challenger Deep,
the deepest part of our oceans.
But would it withstand an erupting volcano?
Or would it be like extra deadly Mentos and Coca-Cola?
Volcanic eruptions involve a lot of heat and pressure.
If we poured concrete into a hot volcanic mouth,
surely it would just melt, right?
Well, not exactly.
Concrete has a melting point of about 1,500 °C (2,700 °F).
Even the hottest orange lava
only reaches 871°C (1,600 °F).
But just because it wouldn’t melt
doesn’t mean it could work.
Volcanoes erupt when the internal pressure from the magma
reaches the point where the ground covering it breaks apart.
Eventually, it collapses,
and the magma runs free.
The greater the pressure difference
between the surface and the magma,
the more explosive the volcanic eruption.
So, putting a concrete plug on a volcano
would be a dangerous addition.
We would be forcing the pressure
to build up below the ground.
Much higher than it usually would.
This would make the inevitable explosion
even more energetic.
If the magma were unable to penetrate the concrete,
it would explode out of the volcano sides.
This is a Vulcanian eruption.
This happened in 1980,
when Mount St. Helens erupted.
The pressure build-up was so massive
that one of the sides was bulging out into a dome.
The pressure became so great that the dome broke,
and the volcano erupted sideways.
This powerful explosion
ejected material at a velocity of 350 m/s (1,150 ft/s).
Dozens of people died.
Our concrete strategy
wouldn't only end up with a Vulcanian eruption.
The concrete plug would burst out too.
The dust from the concrete
would lead to fatal lung diseases and cancer.
The lava flow from a natural eruption
is usually slow and predictable.
So maybe a better plan would be
to use the concrete to divert the flow
away from cities and towns.
Like in 1983, when Mount Etna erupted in Italy.
The lava flow threatened three towns.
Barriers of rock and ash were created to divert it.
The first barrier stood at 18 m (59 ft),
and it was quickly overrun.
The second barrier kept the lava from traveling further west.
So we could use concrete to form barriers or walls
to protect towns and cities.
But you probably shouldn't throw a ton of concrete bricks
into the flow to see what happens.
You might be better off trying something colder.
Like an iceberg.
But that’s a story
for another WHAT IF.