So let's put the river of lava here.
And over here, it hits some water.
Okay.
And sends up tons of steam.
Nice.
There you go.
Oh, hi!
Sam and I have been learning about volcanoes, so now we're drawing a model of one erupting.
Our model is turning out to be very dramatic, but we still haven't decided what kind of volcano we're making.
What kind?
It's a volcano.
That means it's a big, pointy, tall mountain that suddenly goes kaboom!
And everyone runs away going, ah!
Ah!
Save us from the hot lava!
There's more than one kind of volcano.
Are there even bigger and scarier and more explodey ones?
Oh, yeah.
Volcanoes come in all shapes and sizes.
Sometimes volcanoes aren't mountains at all.
Some are the tall mountains like what we're drawing, but others are small hills.
Some volcanoes erupt many times, and some erupt only once.
There are tall and pointy volcanoes, flat and wide volcanoes, and even volcanoes underwater.
Underwater volcanoes?
Going kaboom and scaring all the fishes?
Well, volcanoes aren't just big, scary monster mountains.
The Earth is always changing, building new pieces of itself.
And volcanoes are part of that system.
Okay, but do the volcanoes at least all go kaboom?
Some of them do.
The thing all volcanoes have in common is a vent, an opening in the Earth's crust.
The crust is the top part of the Earth, the part we're standing on right now.
Vents open into the lower parts.
Sometimes a volcano is just a vent, a fissure, or crack in the ground.
Or it might be a crater called a caldera that formed when an eruption... Went kaboom!
Yes, went kaboom!
And then the ground collapsed to create a big pit.
But some volcanoes are giant mountains.
Every volcano is unique, but some volcano shapes might look a bit more familiar to us.
There are stratovolcanoes, also called composite volcanoes, like Mount Fuji in Japan.
They're shaped like cones with a narrow top and a wide bottom.
That's the kind I was thinking of.
When a volcano erupts, hot gases and melted rock from inside the Earth burst out onto the surface.
The hot melted rock is called magma.
When it's under the ground and after it escapes a vent, it becomes lava.
Lava is red hot.
It ranges from 700 to 1200 degrees Celsius.
And then when it cools, it hardens and becomes a layer of rock.
And over hundreds of thousands of years, layers of lava hardened to build up a stratovolcano.
Then there are shield volcanoes, which are giant but with wide dome-shaped slopes, kind of like a superhero's shield, if you look at it from above.
Shield volcanoes also get built up by many eruptions over time.
Mauna Loa in Hawaii is a shield volcano, and it's the biggest active volcano on Earth.
Does that mean that it does lots of activities like soccer and ballroom dancing?
Great question, Sam.
And not quite.
Volcanoes that are active have erupted recently, and scientists think they might erupt again soon.
Dormant volcanoes haven't erupted for a long time, but they might erupt again.
And extinct volcanoes are probably not going to erupt again.
That's too bad.
Not to worry.
We won't run out of active volcanoes.
Right now, there are over 1,500 active volcanoes on Earth, and they have all kinds of eruptions.
Check out the lava that was spewing out of this two-mile-long fissure in Grindavik, Iceland.
And when Kilauea in Hawaii erupts, sometimes fissures release hot lava that slowly moves across the island.
But Kilauea has also erupted into a 300-meter lava fountain.
Holy flying foxes.
Right?
And Kilauea may have slow-moving lava, but some volcanoes have erupted very quickly.
Almost 2000 years ago, Mount Vesuvius erupted in Italy, and it shot volcanic material 33 kilometers into the air at a rate of 15 million tons per second.
Sweet, merciful guano.
That's a lot.
Yup.
And then there was an avalanche.
The nearby towns of Pompeii and Herculaneum were buried so quickly that they were frozen in time, with everything preserved for us to find later, which actually helped archaeologists learn a lot about life in ancient times.
Not so great for them, but pretty neat for us.
Volcanoes can also release ash, a dusty mix of particles from inside the Earth that can be carried long distances by the wind and cause all sorts of trouble.
Eyjafjallajokull is a volcano in Iceland that had a super explosive eruption in the spring of 2010.
Eyjafjallajokull?
That's right, Eyjafjallajokull.
It released a column of ash 10 kilometers tall.
The ash cloud traveled across the Atlantic and over Europe and stopped international flights for a week.
Oh no, imagine not being able to fly.
I know, right?
But Eyjafjallajokull wasn't even the most explosive eruption we know of.
Do scientists have a measurement for how explosive an eruption is?
They sure do.
It's called the VEI, or Volcanic Explosivity Index, and it ranges from zero... Not very splody.
...to eight.
Biggest, boomiest kaboom.
Pretty much.
And Eyjafjallajokull was only a two out of eight.
Only two?
Bummer.
Have we ever had an eight?
The biggest eruption in recorded history was a 7 on the VEI scale.
Mount Tambora in Indonesia erupted in 1815.
The volcanic ash and gases it released into the atmosphere created a cloud the size of Australia.
And that cloud blocked the sun and brought down the Earth's temperature around the world.
The following year, 1816, was called the year without a summer.
Snow fell in the eastern U.S. in July.
Whoa.
All these kabooms are cool, but to be honest, hearing about them all, now I'm a little scared.
Can volcanoes just blow their top any time?
Is there any way to know when an eruption is gonna happen?
Yes, there is.
Most volcanoes give us a warning.
We can track changes in the Earth, like increases in earthquakes or heat, to study when volcanoes might erupt.
And even though they can be a little scary, volcanoes can be helpful sometimes, too.
Volcanic ash can give nutrients to the soil, which is helpful for plants to grow.
And when lava hardens it creates new land and mountains and islands and interesting new places to live, like the lava cooling and the water in our model.
Exactly, Sam.
The Earth is always changing and building new versions of itself, sometimes slowly, sometimes all at once.
And volcanoes are part of that.
Thanks for learning with us today.
If you want to have fun with me, Sam Squeaks and all of our friends, be sure to subscribe and we'll see you next time here at the fort.
Bye.
