Everything Everywhere Daily: History, Science, Geography & More - All About Volcanoes

Episode Date: February 1, 2023

Volcanoes are some of the most fearsome things in nature.  They are responsible for the largest explosions ever known. They have created entire land masses. They have shaped the Earth’s climate and may have been responsible for mass extinction events during our planet’s history.  Today, as you are listening to this, somewhere on Earth, there are over 40 of them erupting right this second.  Learn more about volcanoes, how they work, and how they are different from each other on this episode of Everything Everywhere Daily. Subscribe to the podcast!  https://link.chtbl.com/EverythingEverywhere?sid=ShowNotes -------------------------------- Executive Producer: Charles Daniel Associate Producers: Peter Bennett & Thor Thomsen   Become a supporter on Patreon: https://www.patreon.com/everythingeverywhere Update your podcast app at newpodcastapps.com Discord Server: https://discord.gg/UkRUJFh Instagram: https://www.instagram.com/everythingeverywhere/ Facebook Page: https://www.facebook.com/EverythingEverywhere Facebook Group: https://www.facebook.com/groups/everythingeverywheredaily Twitter: https://twitter.com/everywheretrip Website: https://everything-everywhere.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices

Volcanoes are some of the most fearsome things in nature. They're responsible for the largest explosions ever known. They have created entire land masses. And they've shaped the Earth climate and may have been responsible for mass extinction events during our planet's history. Today, as you are listening to this, somewhere on Earth, there are over 40 of them erupting right this second. Learn more about volcanoes, how they work, and how they're different from each other,

on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the Thurline podcast from NPR. What a volcano is is actually pretty easy to define. A volcano is an opening in the earth's crust that allows for magma from below the earth's surface to come to the surface, expelling gas,

ash, and lava. The difference between magma and lava is that magma refers to molten or semi-multon rock below the surface of the earth, and lava refers to molten rock on the surface of the earth. Defining what a volcano is is much easier than understanding how they work. Every point on the surface of the earth has magma below it. Why don't we have volcanoes shooting up everywhere, or at least at random points all over the planet? The crust of the earth is made up of a lighter rock than the rock inside the mantle. The average density of continental crust is approximately 2.7 grams per cubic centimeter, and the crust on the ocean floor is approximately 3 grams per cubic centimeter. The magma from inside the earth is usually only going to be able

to break through the crust where there is some sort of event or condition that allows it to break through. Most volcanoes on Earth exist at the boundary of tectonic plates. Tectonic plates are the large pieces of the earth's crust that are put together like a jigsaw puzzle. Very slowly over time, these plates actually move, and how they move in relation to other plates depends on how volcanoes are formed. The type of tectonic boundary that creates the most volcanoes are subduction zones. When two plates collide with each other, one plate will usually dive under the other one, slowly pulling the entire plate down into the mantle like a conveyor belt. Due to density, subduction zones only really happen with oceanic crust. This is what is happening along the ring of

fire in the Pacific Ocean. The oceanic plates in the Pacific are moving under other tectonic plates. 70% of all the volcanoes in the world are located in the ring of fire, which is actually a giant horseshoe that extends from southern South America, up through Central America, the west coast of North America, the southern coast of Alaska, the Aleutian Islands, down Russia's Kamchaka Peninsula, Japan, the Philippines, Indonesia, Pocaupe, New Guinea, and then finally Tonga and other South Pacific Islands. Other subduction volcanoes include those in Italy, such as Mount Vesuvius and Mount Edna. The notable volcanoes in the Pacific, which are not part of the ring of fire, are those in Hawaii, which I will get to in a bit. The subduction zones are notable for their deep ocean

trenches where the subduction actually occurs, as well as the many earthquakes and tsunamis which result from the subduction of the plate. As the plate is pulled down, it brings with it an enormous amount of water and other lighter materials with it. The water reduces the melting point of the surrounding mantle, allowing for the formation of liquid magma, which slowly begins to rise as it is now a lower density than the surrounding solid mantle. When it comes up through the surface, the result is a volcano. So to summarize the process for subduction zone volcanoes,

which again make up most volcanoes, it's that one plate is pulled down under another one, the water and lighter materials that are pulled down with it change the chemistry of the rock in the upper mantle, causing liquefied magma to rise up and form volcanoes. Now, if there are subduction zones where a plate is moving underneath another one, that must cause a gap somewhere else. A subduction zone is a convergent plate boundary, where two plates come together. The area where plates move apart from each other is known as a divergent plate boundary.

The best-known divergent boundary is the Mid-Atlantic Ridge, This is a mostly undersea mountain range that extends down the middle of the Atlantic Ocean, snaking its way from Iceland until it reaches the Antarctic plate. In divergent tectonic boundaries such as these, the process is different from subduction zones. The plates are literally pulled apart, which allows for magma to come up to the surface where it's cooled quickly by deep ocean water. Divergent boundaries usually do not result in visible volcanoes. As magma comes up and cools, it stops until the plates spread a point.

part again. The boundary is usually just a long ridge. This is the process by which oceanic crusts, which is lost due to subduction, is recycled and new oceanic crust is created. The amount of magma that comes to the surface depends on how fast the plates are spreading apart. The mid-Atlantic ridge spreads about 25 millimeters per year, and the East Pacific rise spreads at a rate of about 145 millimeters per year. While most volcanoes are the result of plate tectonic activity, not all of them are. The other means by which volcanoes can be formed are geologic hotspots. A hot spot is when a plume from inside the earth's mantle comes right up through the crust. This is due to either an exceptionally hot mantle plume or perhaps a weakness in the crust at that

particular point. Examples of hotspot volcanoes include Hawaii, Yellowstone, the Canary Islands, and Iceland. In the case of Hawaii and the Canaries, there is a chain of volcanic islands. The Chain is created by the tectonic plate moving over the hot spot over the span of millions of years. And the best way to visualize this is if you had a conveyor belt, and as it was moving, you had something stationary below it which kept poking up. As the conveyor belt moved, it would create a series of indentations, even though the object below the belt didn't move at all. The Hawaiian island that's currently the most volcanically active is the Big Island of Hawaii, which is also the furthest east. And the current activity on the Big Island is all in the

eastern side of the island. The big island is the largest, highest, and youngest of all of the Hawaiian islands. As you move west, the islands get older, smaller, and shorter. Active volcanism has ceased on these islands, so there's no more land being created. As they're subject to erosion, the older the island, the more erosion it has experienced, and the smaller it gets. Iceland is a unique case because it is both a hotspot and it's located on the mid-Atlantic rift. Unlike Hawaii, where the plate is moving over the hotspot. In Iceland, the plates are pulling apart right where the hot spot is. The result is not a chain of islands like Hawaii, but just an island that keeps growing ever larger. In addition to volcanoes being formed in different ways, there are also several different

types of volcanoes. Volcanoes are classified into roughly three types. The first is a cinder cone. A cinder cone ejects rocks that are known as scoria and pyroclastics. These are volcanic rocks that are ejected and cooled in the air. The point of the point. Paracoutine volcano in Mexico that I covered in a previous episode is an example of a cinder cone. Cinder cones tend to only erupt once, even if that eruption may take decades to complete. They can often be found on the sides of larger volcanoes, and they're usually the smallest type of volcano. The next type of volcano is a stratovolcano, or a composite volcano.

These tend to be tall, symmetric volcanoes, and they get their names from the different layers or strata which make up the volcano. They can eject both lava as well as ash. Examples of this would include Mount Fuji in Japan, Mount Vesuvius in Italy, Mount Rainier in the United States, and Mount Kilimanjaro in Tanzania. Stratow volcanoes, because they can alternate between lava and ash, can be the most deadly and produce massive explosions. If gases get trapped beneath a magma cap, pressure can build up until it's released catastrophically. Mount St. Helens and Crackatoa are both examples of this phenomenon. The final type of volcano is a shield volcano.

These are the largest type of volcanoes, and they tend to eject only liquid lava. Unlike a stratovolcano which has very steep slopes, a shield volcano has very gentle slopes. It gets its name from the shape of a warrior's shield. Despite having gentle slopes, these are the largest volcanoes. The best example of this, and the world's largest volcano, is Monoloa on the island of Hawaii. They are created by the continual oozing of liquid lava that flows out. Shield volcanoes like Monoloa can certainly cause a great deal of damage if the lava happens to flow into a populated area, but they don't tend to be explosive like stratovolcanoes.

The largest shield volcano known isn't even on planet Earth. It's Olympus Mons on Mars. Olympus Mons is two and a half times the height of Mount Everest, and it has an area about the size of the state of Arizona. If you ever get a chance to visit the Big Island of Hawaii, you'll be able to identify the two main types of lava, can be found in lava fields. Ah-a and Pahoyhoi-A-A is a very sharp jagged type of lava. It tends to form with faster-moving lava that's also a bit cooler. Pahoi-hoi is a smoother type of lava that often looks like ropes in the ground. It's formed by slower-moving hotter lava. You can often find the two right next to each other as when the temperature and viscosity of the lava changes, it will change its form. And it's also easy to remember which is which. Just remember that, ah,

is the sound you would make if you walked over, uh-a, barefoot. According to the Smithsonian Institution's Global Volcanism Program, which is a catalog of all the volcanoes and volcanic eruptions in the world, there have been 9,901 confirmed eruptions from 859 volcanoes over the last 11,700 years. Volcanic activity is a rather confusing subject, because volcanoes work on geologic timescales, not human timescales. There is no scientific consensus as to what an active volcano is. An active volcano usually means that it's either currently erupting or there is subterranean activity going on, which means that it could erupt in the future. Strombole in Italy and Monolo in Hawaii are both very active volcanoes. A dormant volcano doesn't mean that it's seen

the last of its activity. Dormant just means that it isn't currently showing any signs of activity. However, there have been many volcanoes which were dormant for centuries or even thousands of years, which became active again. An extinct volcano is a volcano that is believed will never erupt again as it has exhausted or been cut off from its supply of magma. However, being declared extinct is not a guarantee of anything. There have been several major volcanic eruptions from volcanoes previously thought to have been extinct. The Sufara Hills volcano on the island of Montserrat and the Caribbean was inactive for all of requirements. history on the island. Then in 1995, it erupted, destroying the capital city of Plymouth and causing two-thirds of the population to have to relocate permanently. And it's been erupting

ever since. Montserrat doesn't get a lot of visitors, but if you ever get a chance, I recommend visiting. The Montserrat volcanic observatory is a great experience, and you can even see the rooftops of the ruined city of Plymouth from the sea. Another supposedly extinct volcano was Mount Pinatubo in the Philippines. It's eruption. in 1991 caused global temperatures to drop by half a degree Celsius or 0.9 degrees Fahrenheit for over two years. Historically, volcanoes have been one of the most powerful forces shaping the surface and climate of the Earth. Most of Japan, Indonesia, and other islands were all created through volcanism. Prior to the discovery of the Chixilob crater off the Yucatan Peninsula

in Mexico, it was thought that the Cretaceous tertiary extinction event, which killed the dinosaurs, was caused by a massive volcano known as the Deccan traps in India. Even if it wasn't solely responsible, the deck and traps probably still did have a huge contributing impact. Billions of years ago, the Earth may have been entirely covered in ice in an event known as Snowball Earth. The thing which caused the ice to melt would have been millions of years of volcanic activity. Volcanoes are a really deep subject. People can and do devote their entire lives to their study. Many of the volcanoes I've mentioned in this episode will be the subject of future episodes, and each of them has a unique history and story.

Volcanoes are impressive and powerful. They can shape the earth as well as destroy it. And if you ever get a chance to see an erupting volcano in person, they are truly an awesome sight to behold. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Thor Thompson and Peter Bennett. Today's review comes from listener BB Gun19 over at Apple Podcasts in the United States. They write,

Amazing and very intriguing podcast, My New Addiction. He does an amazing job of providing the right amount of details about everything and everywhere, as the title would tell you. Thanks, BB Gun. I understand that this show can be addictive. However, you do have to be careful. There is no known treatment for this particular addiction. However, you can see counseling over on the Facebook group, or you can commiserate with others who suffer from the same addiction. Remember, if you leave a review or send me a boostagram, you too can have it read on the show.