Volcanologist Answers Volcano Questions From Twitter

I'm Volcanologist, Jenni Barclay.

This is Volcano Support.

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@SereneBRussell, not gonna lie,

the most jarring part about being in Italy

was casually being told what looked like a normal mountain,

super close to where we had been staying was Mount Vesuvius

and that it was still active?

Excuse me?

She's absolutely right.

It is still an active volcano and, in fact,

the last time Mount Vesuvius erupted was in 1944.

And like many volcanoes,

we tend to hear about them in the news

when there's lots of activity going on,

they have a huge impact,

but at any one time around the world,

we manage to live quite happily

with about 40 to 50 volcanoes

erupting anywhere on the Earth.

It is true that for Naples,

Mount Vesuvius having another eruption would be a big deal.

Sometimes it has a really large eruption

like it did famously burying Pompeii and Herculaneum.

Sometimes it has an eruption like it did in 1944

where it generated a relatively more quiet lava flow

and a few smaller explosions.

And Mount Vesuvius

is capable of generating both of those types of eruptions.

Okay, this question is from jzaceanna.

God just be making pointless [beep]

Why the [beep] do volcanoes exist?

Volcanoes do seem a bit destructive,

but, actually, over geological time,

volcanoes first formed

and what they did is they transported

a lot of really useful things like water and oxygen

from the interior of the Earth to the outside of the Earth.

So to be honest, without volcanoes on the Earth,

we wouldn't be here either.

@ellecapric says there's a volcano in Indonesia

that spews blue lava!

I mean, what sorcery is this?

Blue's not really a color

that you'd associate with volcanoes, it's red,

but the blue is a really special condition

for that particular volcano.

It's really full of sulfur.

And when that sulfur erupts as the lava's coming out,

it's not the lava itself that's blue,

but it's the gas that's associated with it

and it creates this ethereal blue flame

that really does look pretty spooky over the top of it.

So the next question's from @1ayarbrough18.

Why are Iceland volcanoes so active?

So Iceland is an island sticking out in the Atlantic Ocean,

and Iceland is there just like Hawaii

because of the huge amounts of volcanic activity over time.

And that volcanic activity has meant that that has built up

from really deep in the sea floor

and now sticks above the ground.

And unlike Hawaii, Iceland is also located on a rift.

So where the plates are moving apart like that.

So what that means is there's two different mechanisms

that help to generate that magma.

And every now and then that magma

has to make its way to the surface,

and that's why their volcanoes are so active.

So this question is from @moravaginelol.

What do volcanologists even really do

except sit around talking about how bad ass volcanoes are?

What else is there to be studied?

They're volcanoes.

Hmm, slightly rude.

What I spend a lot of my time doing

is I like to look at rocks.

They're the secret recorders of some of the things

that have happened to the magma before it erupted.

And it unlocks lots of clues

about how volcanoes are going to erupt.

This is basically frozen magma.

And by examining this,

we can understand what sorts of things were in the magma

that caused it to erupt.

Volcanic rocks are also erupted with crystals in them.

You can maybe just about see the crystals now

in this magma here.

And believe it or not,

crystals grow with very specific composition

that we can use to unravel the pressures, temperatures,

and the changes that happened

that caused that magma to go from being nice, gentle magma

sitting around quietly underneath the Earth's surface

to something that erupts and causes destructive mayhem

that we associate with volcanoes.

One of the really big challenges we've got as volcanologists

is the warnings for us are understanding when that magma

underneath the surface is on the move.

And these are my modern measuring devices, if you imagine.

And what we can do now is imagine in the subsurface

we've got these areas where magma might come through.

Now as the magma pushes up here,

you can see it's starting to push and go

where it otherwise wouldn't have been.

So it creates all sorts of tension

in the rocks around there,

which create little waves

that we can pick up with our splendid detecting devices

and we can tell how those waves have been generated

and what's going on with that.

And the other thing that happens

is as the magma starts to push up,

it actually makes our little volcano start to deform

and it will change its position,

which would mean that also what we can measure from,

well, here's my funky satellite here.

What we can measure by satellite

is changes in the surface of the Earth.

The next question is from Bruhbot747.

My question is, what's your favorite volcano?

Mine would be Mount Saint Helens.

My favorite volcanoes are all called Soufrière.

I've done huge amounts of field research

in the Eastern Caribbean.

The little islands there are a line of volcanoes.

Many of them have the named Soufrière in their title.

So I love Soufrière Saint Vincent on Saint Vincent,

and Soufrière Hills Volcano which is on Montserrat.

When these volcanoes erupt,

what they do is they produce spectacular explosions

and sometimes they erupt slowly and gently,

not the red hot lava flows that you might expect,

but buildup of dome material at the top of the volcano.

However, when those collapse back down,

they generate deadly pyroclastic density currents,

mixtures of red hot ash and gas,

and they come flying down the hillsides at speeds

that are much greater certainly than you can run from

and almost definitely that you could drive from.

And these are something that are lethal

for anyone who's in their way.

@Han_i17, how are people standing so relaxed

near four live volcanoes in Iceland?

Volcano tourism?

So unreal.

Volcano tourism isn't a new thing,

but if you remember the idea of the Grand Tour Of Europe,

and one of the things that many tourists

would do 200 years ago is they would go and visit

the amazing volcanoes of Italy,

including Stromboli and Etna,

which are frequently erupting.

And, of course, the amazing spectacle

of Vesuvius and Pompeii near Naples.

And one of the things that they can do

that's really frightening

is they can erupt explosively and suddenly,

and this can and does catch people unaware.

Make sure you follow really closely official advice

about that volcano.

@katy_nickleson1 is wondering where is the biggest volcano?

Define big.

So if by big you mean the tallest,

one of the tallest volcanoes are actually Mauna Loa

and Mauna Kea in Hawaii.

The remarkable thing about them is they've got

about four or 5,000 meters worth of heights below sea level.

They've had to build all that way up from the sea floor,

and then they've got another 4,000 meters on the top.

So once you count that level of building,

they're taller even than Mount Everest.

Technically, the tallest volcano

in terms of height above sea level,

they tend to be in the high Andes,

which is, of course, a very high mountain range,

and they're over six and a half thousand meters.

And the big tallest volcano in the world in that sense

is Nevado Ojos del Salado.

Another way of measuring how big a volcano is,

is how big the eruptions that it produces.

So, of course, there are the supervolcanoes,

none of which have erupted in living memory,

but historically, the largest volcanic eruption

was Mount Tambora in Indonesia, which erupted in 1815.

And that created noises that were heard in Australia.

@TaylorMacP says, Forgive me, he's forgiven,

but what makes a volcano a supervolcano?

Is it when multiple volcano eruptions combine,

like a perforated ulcer?

So strictly what makes a volcano a supervolcano

is when it has a supereruption.

And your imagery of a perforated ulcer is kind of

a little bit right in terms of all sorts of magma coalescing

and coming together to create a huge volume of material

that would be erupted out all at once.

And a supereruption is when you have

a thousand cubic kilometers of material erupted all at once

from the interior of the Earth outside.

And luckily that's something

that really doesn't happen very often.

@erinswonderlxnd is wondering

why do volcanoes have different shapes?

And what plate boundaries do you find at each?

Someone help.

Google ain't helping strata.

Stratovolcanoes tend to have much steeper slopes,

that kind of classic volcano shape that we think of.

Whereas, shield volcanoes

tend to have much lower angle slopes.

In different types of plate boundaries

there is a tendency for particular types of magma

to be generated.

So in the seduction zones

where we've got one plate going underneath the other

big explosive eruptions create lots of material.

And so they pile up quite quickly

creating what we think of as the classic volcano shape.

And in areas where you've got more gentle flows,

you'll have more shield volcanoes.

@abbe_smith_ wants to know

what has been the longest continuous eruption?

Stromboli, for example,

an island off the coast of Italy

has been erupting for thousands of years.

It has little explosions.

Even the Romans used to refer to Stromboli

as the lighthouse of the Mediterranean,

and it's had a few pauses

that mean it's not the one that's thought of as continuous,

but this volcano that we know

that's been going the most continuously

is Santiaguito Volcano in Guatemala,

which has been erupting continually since 1902.

@aWastedHour is wondering

what country has the most volcanoes, active and extinct?

The United States of America,

which has got many volcanoes in many different states

along the West Coast,

but in fact I would say the country

with the most active volcanoes, so where, for example,

there are seven volcanoes erupting right now is Indonesia,

and that's definitely the country

that's had the most volcanoes that have erupted since,

for example, 1950.

So, @bl_AAH wonders supervolcano overdue for an eruption?

Could wipe out the whole U.S.?

Bitch what?

I think what you're worrying about is perhaps

the supervolcano that you find in the U.S., Yellowstone.

Its supervolcanic eruptions are about 300,000 years apart.

And to be honest, supervolcanoes

don't always have supervolcanic eruptions.

And what Yellowstone most often does

is it has much smaller eruptions, supervolcanic eruptions.

So ones with those huge volumes of material happen

really, really infrequently.

We're talking many, many thousands of human lifetimes apart.

So @JediMasterRoman.

Trying to wrap my head around how volcanoes

can cause tsunamis is [beep] wild.

You're right.

In the case of volcanoes, when they erupt

a huge amount of material

that all comes back down into the sea at once,

that creates the displacement that can generate a tsunami,

but the other thing is that volcanoes

build themselves up chaotically,

and from time to time they can completely collapse.

So if a volcano collapses down into the sea,

then it can generate a tsunami as well.

So most recently there was an eruption of Anak Krakatoa

and it had a big eruption that generated a tsunami

and that inundated many of the villages nearby.

@RedErinn is wondering

what's the dark, glassy volcanic rock called?

It's called obsidian.

It's absolutely fantastic.

If anyone plays Minecraft, you might have seen this.

This is real obsidian,

and this is actually from the island of Lipari

off the coast of Italy.

And what this is, is this is volcanic rock that was magma

where the melt has quenched so quickly,

it hasn't made any crystals,

but actually turned itself into glass.

And if you took a tiny little shard off this,

you would almost be able to see through it.

It's also very, very sharp.

It was used by many cultures as a cutting implement.

So, for example, Native Americans in South America,

the Maori in New Zealand,

pretty much anywhere where they could access

this really special type of volcanic rock.

So, @ProBucks_ asks.

Weather dummy here.

How do volcanoes cause lightning?

So volcanoes cause lightning

separate to the kind of lightning phenomena

that we see in the atmosphere

because when we have an explosive eruption,

huge amounts of ash is thrown out into the atmosphere

and that's actually electrostatically charged.

And so the differences in charge

across the plume that's generated by that explosion,

create lightning.

@quietbatpeople is wondering

why do volcanoes become inactive?

And that's an easy answer.

Volcanoes become inactive when it runs out of magma

that can get up to the surface.

We either think of volcanoes as potentially active.

Active, which means in the process of erupting or extinct.

So dormant I think really means

when you think it could erupt again, but it might not.

And we tend to refer to those

as potentially active volcanoes.

And around the world on land

there are about 1,400 of these volcanoes.

@cacie has got a really interesting question.

Questions from five-year-olds.

What would happen if I fell into a volcano?

So if you fell into the crater of an active volcano

and say, for example, it had a hot lava flow in the crater,

that lava flows at about 1,200 degrees centigrade.

So super, super hot.

So certainly a temperature at which it would be

very difficult to survive for very long at all.

This is an interesting question from @McKenzieturman.

If volcanoes create new land,

how did the first volcano come about?

Almost philosophical.

Actually, magma was first.

Believe it or not, when the Earth was first formed,

it was a giant ball of magma.

And, actually, it was as that started to cool down slightly,

that land was able to be formed.

So the volcanoes were absolutely definitely first,

but the planet was one giant ball of magma.

And it wasn't until it created the land that the volcanoes

had to start pushing out through that land and forming.

@SLVRDreams, I just thought of something.

If sea levels can rise

and undersea volcanoes erupt to create new land masses,

does that mean Earth

is gradually becoming a bigger sphere over time?

Can you answer this?

Well, SLVRDreams, that's a really good thought.

So if we're thinking about things erupting

and moving apart like this,

then you would think that over time

the earth would be getting bigger,

but, actually, because of plate tectonics,

these plates are growing and moving like this,

creating new landmass,

but at the same time, at the other end,

there's plates that are going down underneath one another

and destroying them.

And both these areas are where volcanoes can be created,

but there what it means that over time

the Earth has remained the same size.

The next question is from @iracooke.

How does volcanic ash from South America

stop flights to Melbourne?

Pretty amazing stuff!

I'm hoping my flight makes it.

So perhaps you will all remember

when flights were stopped in 2010 from Eyjafjallajökull

and that was a really unfortunate circumstance

of atmospheric circulation

that was pushing ash towards Europe.

So they had to close European airspace.

And that's, of course, because there's all sorts of

different types of atmosphere circulating.

And once volcanic eruptions are sufficiently big

that they inject material up into the upper atmosphere,

or the stratosphere,

that ash and those particles get traveled all around.

And guess what?

Airplane engines do not like those particles.

They operate at temperatures

that will turn that volcanic ash back into, if you like,

magma and stick to the propellers,

which is really not a situation that you want

if you want them to keep going round.

So for that reason,

when there's volcanic ash in the atmosphere,

airplanes will avoid it.

So, @kolsenjd, do volcanoes communicate with one another?

So it's not like in the Disney film Lava

where the volcanoes sing nice little songs to one another

as they grow and fall back into the sea,

but it is possible

that when magmatic systems are close together,

so the volcanoes at the surface are close together,

their feeder systems,

as there's things moving around in one system,

the resonance and the pushes and the shoves in the ground

get transmitted to another.

So it's not that they'll erupt all one after another,

but it's possible that some of those stresses and strains

that we see in the subsurface

do travel from one system to another.

So, @jessphoenix2018 is wondering,

have you heard any of the volcanic infrasound recordings?

My colleague, Jeff Johnson at Boise State

records the sound volcanoes make

below the range of human hearing.

It's captivating.

Yes, I have heard those infrasound recordings

and they are captivating.

So when volcanoes erupt,

they cause all sorts of displacements and movements

in the atmosphere and in the rocks that surround them

as the magma is moving up.

And these generate waves

and the infrasound waves when you change their frequency

can be turned into sound waves that give an amazing record

of some of these processes that are taking place.

It's well worth checking out.

@Mathew_C_R has a question.

When it comes to geological terms, what is the Ring of Fire?

Where is it in terms of plate boundaries?

So here we go.

This is a map of the Earth,

and these white dots show the plate boundaries of the Earth.

And you can see marked really clearly

around the Pacific Ocean here

we have this big run of plate boundaries,

and they all happen to be the plate boundaries

where one plate is going down underneath another

that generates quite a lot of explosive volcanism,

hence the name Ring of Fire

because there's lots of volcanoes

all around this plate boundary and it surrounds the Pacific.

Okay, so @jhumphre.

Ever wonder why some volcanoes like Mount Saint Helens

erupt explosively,

while others, like Kilauea, ooze lava?

One of the things that's really amazing about volcanoes

around the world

is there's all sorts of different types of magma,

and these different types of magma

lose and grow gas within them in different ways.

So, for example, this is a magma that's a little bit more

like what you might see in Kilauea.

And you can see it's got these great big bubble holes,

and that's because the gas can move around

quite freely in the magma,

but other types of magma

are kind of quite resistant to that.

And they create lots and lots of tiny little bubbles,

which creates huge pressures

that mean when the volcano finally explodes,

there's a huge release of that pressure

generating very large explosive eruptions.

And those large explosive eruptions

generates something like this, which is pumice,

which is super light.

And the reason it's super light is because

it's absolutely full of holes,

which are a record of that gas

trying really hard to get out

being resisted by that type of magma.

And I'm gonna put this into the beaker

and it's gonna float.

And it's floating because it's super light,

because it's largely composed of bubbles

with just tiny little filaments of volcanic glass.

Okay, so @EBatterson is wondering,

where do volcanoes get the magma/lava?

Now, lots of people think there's a huge sea of magma

just below the crust.

That's not true.

There's not magma everywhere.

It's particular conditions that are created

to generate that magma.

And I'm gonna show you this for a subduction zone.

So here's one plate, it's diving down.

Here's another plate here crashing into it, okay?

Now what happens is as that plate goes down,

it gets heated up and squeezed and it gives off fluids.

And those fluids create the special conditions

where melt can be generated.

Now that melt has got liquid in it,

so liquid rock if you like,

but it's also got gas and it's hot.

And what that means is that melt has a tendency to rise,

and as it rises up towards the surface it will come out.

And then eventually what we have is our volcano.

I've been loving your questions from the internet.

This has been Volcano Support signing off.

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