Hi friends, welcome back to the fort.
Squeaks is showing me some pictures from his vacation to Iceland.
He had a really good time.
Oh, where should you visit next?
Well, Iceland is pretty chilly.
Maybe someplace warmer?
Oh, but you wanted to try and visit another island.
Warm islands.
I've got it.
How about Hawaii?
Hawaii is one of America's 50 states and is found here in the Pacific Ocean.
It's nice and warm there all year long.
And Hawaii is made up of lots of smaller islands.
Yes, you're right, Squeaks.
There are volcanoes in Hawaii.
Well, yes, I can see why volcanoes can be scary.
Sometimes they can change pretty quickly and suddenly erupt.
But we have ways to keep people safe.
So safe that we can enjoy how amazing and interesting volcanoes can be.
There are 15 volcanoes on Hawaii's eight biggest islands.
Six of them are active.
Active means that they've erupted in the recent past and may erupt again.
A volcano erupts when a material like gas, rock or lava moves from inside the Earth into either the air that surrounds Earth or onto Earth's surface.
Four of Hawaii's active volcanoes are on Hawaii's biggest island.
They are Kilauea, Mauna Loa, Hualalai, and Mauna Kea.
Good observation, Squeaks.
That's a lot of active volcanoes in one area.
There are a lot of volcanoes and earthquakes in this area of Earth.
There's so many that scientists nicknamed it the Ring of Fire.
This map shows the Ring of Fire.
It shows where the land is and where there's ocean.
And this is the Ring of Fire.
It looks like part of a circle.
Why are there so many volcanoes?
Well, the Earth is made of layers.
We need to take a closer look at Earth's crust, its outermost layer.
It is made of large, odd-shaped pieces called plates.
These plates are always moving.
They make up the land we're standing on right now.
I know we can't feel the plates moving because they're moving super, super slowly.
They only move about 1.5 centimeters every year, about the speed a person's toenails grow.
Even this very slow movement of these plates is enough to cause big changes on Earth.
Earthquakes and volcanoes tend to occur along the edges of these plates.
But there's more happening in the Ring of Fire than just around its edges.
There's a long chain of islands that runs through the middle of the Ring of Fire.
We can see these islands on a map, too, and many of them make up Hawaii.
How did all of these islands get there?
All of the volcanoes in this long chain formed because of the Hawaiian hotspot.
A hotspot is a place in Earth's middle layer, the mantle, that is extremely hot.
Do you know how on a hot day an ice cube will melt into liquid water?
Rock can melt when it gets hot, too.
The heat from the hot spot rises, which melts the rock above it.
This melted rock is called magma.
The magma then continues to rise.
When some of it pushes its way to the surface, the magma comes out as lava, and that's a volcano.
Good observation, Squeaks!
Eruptions can be sudden, so how can an island form over a long time?
Many volcanoes are like Kīlauea, which has been erupting lava slowly and over a long period of time instead of all at once.
The lava from this eruption oozed out of Earth's crust over about 35 years.
Then the volcano did erupt more quickly, causing the very shape of the island to change.
This is one of the reasons volcanoes are so interesting.
Sometimes they can have big eruptions that change things really quickly in one fell swoop, and other times they make changes over a much longer period.
For example, one of Hawaii's six volcanoes, Kamaehua Kanaloa, is underwater.
It would be here on our map.
The top of this volcano is about 1,000 meters underwater.
This is a clue that it's not as old as Hawaii's other volcanoes.
How is it a clue?
Well, let's imagine what it would look like if an underwater volcano kept erupting.
What would happen to the lava?
It would get wet, but it would also cool off.
And when lava cools off, it hardens back into rock.
And as more and more lava flows out and gets cool, it starts to pile up.
What do you think would eventually happen?
Oh, that's right, Squeaks!
It would peek out of the surface of the ocean.
And that's how all of Hawaii formed.
The islands of Hawaii formed very slowly because of lava erupting, cooling and piling up until it reached the surface of the ocean over millions of years.
This is a great example of change taking place slowly over a long period of time.
Squeaks wants to know how we know it's safe to be near an active volcano.
If scientists think that the volcano might erupt, they let everyone who might be affected know and they will give people instructions on what to do depending on how the volcano is erupting.
That might include moving to higher ground, away from lava flow, or moving inside to stay safe from ash.
If you are in an area around a volcano, it's always a good idea to look for signs like these and to make a plan in case you have to leave the area.
But no need to worry, because scientists are always keeping an eye on volcanoes in lots of different ways.
For example, they use a tool called a seismograph. to detect how the ground is moving.
Earthquakes which are caused by the movements of those big plates often happen before a volcanic eruption.
So if the ground is moving, that could be a sign an eruption might happen soon.
Scientists also watch the ground to see if it shifts or bulges up at all.
This might mean magma is close to the surface, and the volcano might erupt.
They even measure the kinds and amounts of gases coming out of the volcano.
When they put all of these observations together, they can usually predict when a volcano will erupt and give people plenty of time to get to a safe place.
Squeaks says now that he knows how volcanoes work, he's really excited to visit Hawaii.
Thanks for joining us today.
If you want to keep learning and having fun with Squeaks me and all our other friends, be sure to hit the subscribe button and we'll see you next time on SciShow Kids.
