Hey, everyone!
It's Justin here, and welcome to today's episode of... [drumroll]
"Catastrophic Natural Disasters." [siren blares]
[siren continues blaring] That's right! Devastating volcanoes! Cataclysmic earthquakes!
[siren ceases] We'll also be taking a brief look at the Earth's layers and plate tectonics, but mostly we're talking about...
[siren blares] catastrophic
[siren blares] natural
[siren blares] disasters!
[siren ceases] So, get your hard hats and your seismometers because this riot could get a little bumpy.
Imagine, for a moment, that it's the year 79 A.D., and you're in the ancient Roman city
of Misenum because your uncle is a military officer stationed there.
You're out on the terrace eating your breakfast, enjoying the magnificent view of the Bay of
Naples, Mount Vesuvius, the bustling resort city of Pompeii.
You are living your best life right now, and you're about to shove this beautiful wheat
pancake into your mouth... when you're suddenly interrupted by a booming rumble. [rumbling]
The Earth beneath you begins to shake. Roof tiles begin to crack and fall all around you,
when all of a sudden, to your horror, in the distance, molten rock begins to spew
from the top of Mount Vesuvius, along with a huge dark cloud, swallowing the city of Pompeii
with it.
[chaotic crowd] You hear screams, confusion, and then darkness as humongous plumes of ash blot out the sun.
That is the exact scene witnessed and described by young Roman scholar Pliny the Younger,
whose uncle, Roman philosopher Pliny the Elder, died in what is perhaps the most infamous
volcanic eruption in recorded history, the one that buried four Roman cities and killed
2,000 people.
Hold on, what was that?
How did this happen?
Good question.
Volcanoes form when molten rock or magma breaks through the Earth's crust.
(The Earth's crust being the top layer of the Earth covering the mantle.)
(The mantle being the mineral layer covering the core.)
When magma with high-pressurized gases breaks through to the surface, it erupts with enormous
force, spewing rock, ash, and lava for miles.
That is exactly what happened to Mount Vesuvius in 79 A.D. and the reason why Pompeii was
buried underneath 30 feet of ash and remained buried underneath 30 feet of ash until 1748,
when explorers digging there made an amazing discovery.
Underneath all that ash, Pompeii was perfectly preserved, exactly as it was almost 1,700 years ago.
The people of Pompeii, and even the pets, like this guard dog here, were perfectly captured
in the exact moment of what they were doing when that ash cloud swallowed them.
Another infamous volcanic eruption was when Krakatoa in Indonesia erupted in 1883, throwing
five cubic miles of earth 50 miles into the air, causing temperatures to drop worldwide
and creating a pressure wave that circled the globe three and a half times.
The eruption was so violent that sounds of it could be heard on the island of Rodriguez,
near Mauritius, over 3,000 miles away.
That's further than the distance between Los Angeles and New York.
Imagine for a second if something happened in Los Angeles, and you heard it happen in New York.
That's how powerful the Krakatoa eruption was.
In terms of quantifiable energy, the force resulting from the eruption was equivalent
to 200 megatons of TNT.
That's 13,000 times the yield from the atomic bomb that devastated Hiroshima, Japan, and
four times greater than the explosive yield of the largest nuclear device ever tested.
We are talking about massive forces within the Earth, capable of doing things like creating
islands where there weren't islands before. Islands like... Iceland in the North Atlantic,
one of the most volcanically active places in the world.
Iceland is home to 130 volcanoes, and the country has a population of only 357,000.
So, that means one volcano for every 2,746 people.
Tired of your hometown not having its own volcano?
Consider relocating to Iceland.
One of Iceland's volcanoes, named...
...
Uh, how do you say that?
[voice off screen] "Ay-uh-fyaat-laa-yokt"
[Justin] Oh, right, of course, obviously.
Um.
So, this volcano that starts with the letter E is a stratovolcano completely covered
by an ice cap with a– Hold on.
What?
What's a stratovolcano, you ask?
A stratovolcano is a volcano with thick, gummy lava that doesn't flow very far from where
it erupted, meaning that the stratovolcano is taller and more conical, as opposed to
a shield volcano, which is broader and many times wider than it is tall because its lava
isn't as thick and gummy, and therefore, it can flow further from the point of eruption.
Anyway, this stratovolcano named...
...
[whispers] Okay, one more time.
[voice off screen] "Ay-uh-fyaat-laa-yokt"
[Justin] Ay-uh-fyaat-laa-yokt
[ding-ding-ding!] [fireworks]
Nailed it!
...erupted in April 2010, darkening the skies with ash and causing massive disruptions to
air travel all over Europe.
So, about now, you're probably thinking, "Why on Earth would anyone want to live near a
volcano?"
Excellent question.
One good reason to live near a volcano is to harness geothermal energy, which is the
heat from within the Earth.
Iceland makes great use of geothermal energy.
As a matter of fact, 90 percent of Icelandic homes are heated with geothermal water, which
is cooled and pumped straight from deep within the ground directly into taps.
Another great reason to live near a volcano is for the rich quality of volcanic soil.
Mauna Loa in Hawaii, which is the largest active volcano in the world and a superb example
of a nice, broad shield volcano, has been erupting on and off and depositing mineral-rich
volcanic debris on the ground for the last 700,000 years.
This volcanic debris gets weathered, or broken down, by rain and erosion over time.
The result? Hawaii and other volcanically active areas, like Antigua, Guatemala, have
rich volcanic soil that can be used to grow a wide variety of plants.
Plants like... [drumroll]
coffee.
That's right, folks!
If you want to grow world-class coffee in the shadow of not one but three stratovolcanoes,
consider relocating to Antigua, Guatemala, where the coffee is three times as volcanically delicious!
Now, I bet you're thinking at this point, "Isn't living near an active volcano kind of dangerous?"
You bet it is.
Look at what happened to Pompeii.
That's why, nowadays, geologists use technology like seismometers to record little earthquakes
in the areas around volcanoes.
These earthquakes can be used to predict whether or not a full eruption can occur.
So, if you choose to relocate to an active volcano to grow your coffee, maybe consider
sharing some of that coffee with your local geologists because they're the ones keeping
an eye on that volcano and going to be telling you whether you should stay.... [rumbling] or run.
Now, I just mentioned earthquakes, which is another potentially catastrophic natural disaster
that comes from the Earth.
So, how do earthquakes work?
Glad you asked.
The solid outer layer of the Earth, called the lithosphere, consists of the crust and
the upper mantle.
It's split into 15 to 20 huge slabs of rock called tectonic plates.
Heat from within the Earth causes these tectonic plates to move, and their edges stick together
along points of friction.
If a tectonic plate's motion overcomes this friction along a fracture zone, or a fault,
that causes the shaking that we know as an earthquake, and if the same process happens
underwater, that resulting earthquake could create a huge ocean wave called a tsunami!
In 1500 B.C., a massive earthquake struck near Knossos, Crete, in conjunction with a massive
volcanic eruption that happened on the local Greek island of Thera, now called Santorini.
The earthquake, the volcanic eruption, and the resulting tsunami are credited with wiping
out the entire Minoan civilization, a Bronze Age civilization that's renowned for its great
cities, its writing, and its works of art.
Port Royal in Jamaica in the 17th century was a haven to all sorts of nefarious characters
in the Golden Age of Piracy.
It too was also wiped out by an earthquake and resulting tsunami on June 7th, 1692, at 11:43 in the morning.
How do we know that?
Because a pocket watch stopped at 11:43 was recovered some 270 years later on the ocean
floor near the earthquake site!
[in a pirate voice] Personally speaking, I thinks it was the kraken that caused all the shakin', but
that be only me opinion.
Yarrrg!
In 1994, a powerful earthquake struck the United States in Northridge, California.
The quake collapsed freeways and buildings, but overall destruction was kept to a minimum
because of the widespread use of
earthquake-resistant construction.
We've talked a bit about why you might want to live near a volcano, but it's kind of hard
to find a reason why you'd want to live near an earthquake fault, unless you really needed to.
California is located in an area bordering the Pacific Ocean called the Ring of Fire,
where a number of tectonic plates move and collide, creating subduction zones where eruptions
and earthquakes frequently occur.
Many people in California work in Los Angeles, the world's capital for entertainment.
Many more Californians work in Silicon Valley, the world's capital for computer technology.
A lot of people need to be in these areas to do the work they do, and it's not always
possible to work remote, although that is becoming more common.
So, what do Californians do?
They adapt.
The state of California, as well as a lot of local municipalities, have adopted building
codes meant to make construction more earthquake-resistant.
Plus, a lot of builders will implement special designs and materials like flexible foundations,
pendulums, dampeners, memory alloys to protect their buildings from earthquake shock.
Powerful forces within the Earth have been creating land masses and destroying cities,
even entire civilizations, for thousands of years. From Pompeii to Northridge,
people living near volcanoes and earthquake faults have adapted, like by using seismometers
to detect earthquake activity, for example, or by harnessing the heat from the Earth in
the form of geothermal power.
As we move forward in your study of geography, I want you to keep in mind the natural forces
that shape where you live and how people there adapt to survive and thrive.
Until next time, keep exploring!