Episode 18: Underwater Volcanoes and Crystals

Dr. Universe and a group of junior scientists from Palouse Prairie Charter School learn about underwater volcanoes and crystals. Students from the fourth-grade class in Moscow, Idaho help Dr. Universe answer earth science questions.

Another big thank you to Northwest Public Broadcasting for help with recording! You can find sources for information about underwater volcanoes and crystals in the transcript.

As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.

Dr. Universe

Hey, cool cats. I'm Dr. Universe, and if you're anything like me, you have lots of big questions about our world. You know, I get a lot of questions from young scientists, and the other day I got a phone call from Palouse Prairie Charter School.

Renee Hill

Hi, Dr. Universe? It's Renee Hill. Our fourth grade crew was wondering if you could use any help answering some of your science questions.

Dr. Universe

Answering all these questions is a big job for one cat. That would be amazing. Let's do it. I'll send you some geology questions soon. Thanks so much.

Renee Hill

Bye, Dr. Universe.

Dr. Universe

On this episode, you'll hear from our fourth grade scientists as they help us investigate some cool science questions from kids. Up next, we're exploring underwater volcanoes. This question comes from Fatima, age nine, in Nigeria. Can a volcano be underwater? Matilda, what did you and your group find out?

Matilda

There are underwater volcanoes. Underwater volcanoes are called submarine volcanoes. Those that rise at least 1,000 meters -- about 3280 feet above the sea floor -- are called sea mounts. About 75% of all volcanic activity on Earth happens under the ocean, and many unique deep sea creatures including tubeworms and even trip with eyes on their backs can live in underwater volcanoes. If you become a scientist, someday you might even get to explore one. Here's Lena with more about how underwater volcanoes form.

Lena

Underwater volcanoes can form in three ways. When tectonic plates diverge, when tectonic plates converge, or over a hotspot. Underwater volcanoes usually form between two tectonic plates of oceanic crust. Which is just a different way to say the ground that's underwater. At convergent plate boundaries, a process called subduction occurs where one tectonic plate sinks under another one. As the sinking plate goes deeper into the Earth's mantle, it melts into magma. Every time the volcano erupts, the lava cools, forming basalt rock that hardens on a small mound and makes the volcano bigger and bigger.

Dr. Universe

Some tectonic plates converge, but others diverge right?

Lena

Yes, an underwater volcano can also form when two tectonic plates separate or diverge. When this happens, the magma below the tectonic plates rises up through the space between the two plates. As the lava flows out, it cools down and forms the mid-ocean ridge that becomes new oceanic crust. Mid-ocean ridges can form some of the highest mountains and deepest canyons on Earth, but we don't usually see them because they're underwater. Submarine volcanoes can also form in the middle of a tectonic plate at what are called hotspots. Hotspots are places where the Earth's mantle, or layer of rock between the crust and the core, is hotter than usual. So rock melts, and magma rises to the surface. The Hawaiian Islands is a chain of underwater volcanoes that formed from a hotspot in the middle of a Pacific Plate. Did you know that Mauna Kea on the Big Island of Hawaii is the tallest mountain in the world? Its peak is only about 13,796 feet above sea level, but more than half is hidden under the ocean surface. So it is actually about 33,500 feet tall. Mount Everest, which many people think is the tallest mountain, is only about 29,029 feet tall. Now you know how underwater volcanoes formed, but what happens when they erupt?

Mo

I can tell you more about that.

Dr. Universe

Thanks Mo.

Mo

Some submarine volcanoes are explosive and blast steam, rock, and other debris above the surface. The ocean currents and the wind can carry the debris all over the world. Other submarine volcanoes are deep under the ocean, and the runny lava slowly moves along the sea floor. We can sometimes see submarine volcanoes that blast out of the ocean, but we can't easily see the deeper ones that aren't very explosive. Scientists study submarine volcanoes and seamounts to help us learn about our planet and how it was formed. They explore in submarines, send remote control robots, and study images taken from satellites. We have learned a lot about all the volcanic activity under the oceans, but the eruptions are very hard to observe while they are happening. We often know about them because of the impacts they have. When an underwater volcano erupts, debris like ash, chunks of rock, and dead fish -- yeah, dead fish; gross, I know -- come out and float to the surface of the water. Eruptions can also cause tsunamis, which is a large wave or series of waves that can cause flooding and damage to animals, plants, humans, and buildings. Okay, so now you know how they arrived and how they form, but you might be wondering, what are some actual underwater volcanoes?

Student

Mo, I can tell you all about that. Most of the active volcanoes on Earth are underwater in the Ring of Fire. The Ring of Fire follows the boundaries of several tectonic plates, making a U shape around the Pacific Ocean. The Ring of Fire includes 75% of Earth's volcanoes, and 90% of Earth's earthquakes occur on this path. We know a lot about volcanoes on land in the Ring of Fire, but we still have a lot to learn about submarine volcanoes. However, there are many well-known submarine volcanoes. Kavachi is a shallow volcano located in the Solomon Islands. It is one of the most active volcanoes in the Southwest Pacific. Its first recorded eruption was in 1939, and it has erupted more than 30 times since then. Kavachi has risen above the surface of the ocean before eroding back down multiple times since 1950. Axial seamount is the most active submarine volcano in the Northeast Pacific. It is located on the Juan de Fuca Ridge off the coast of Oregon. The last time Axial erupted was in 2015. Axial has erupted four times since 1976, but there is evidence that it has been erupting since the year 410. One of the most recent big submarine explosions was on January 15, 2022. A giant underwater volcano in the Pacific Ocean called Hunga Tonga-Hunga Ha'apai erupted. The cloud of ash and dust was so big that it was seen from space. This set off tsunami warnings and caused rising water levels all across the Pacific Ocean. Here's Matilda with their final part of the show -- plus a joke.

Matilda

So, the answer to the question "Can a volcano be underwater?" is yes. Not only do underwater volcanoes exist, most volcanoes on our cool planet are in fact underwater. Hey, Paige, what did the hot sea volcano say to the cold sea volcano?

Paige

Um, I don't know. What?

Matilda

You're too cold to be a submarine volcano.

Dr. Universe

Now we turn from volcanoes to another fascinating area in the world of earth sciences. Alya, age 9, in Washington state asked, "How do crystals form?"

Gunnar

Hi, I'm Gunnar. You might be surprised to know that diamonds and snowflakes have a lot in common. They are both a type of crystal. Crystals are any solid material in which the atoms are arranged in repeating patterns. Did you know that the graphite in your pencil, the salt in your food, and even the screen of your laptop are crystals, too? Also did you know that some crystals are almost as old as the Earth? Here's Mateo with more on how crystals form.
The process of crystals forming is called crystallization. Crystals form in two basic ways: cloning and evaporation. The most common way that crystals form is when magma deep within the Earth's crust cools and hardens and mineral-rich fluid separates out. Crystals can also form from water evaporating. For example, salt crystals form when salt water evaporates. The reason these all result in crystals forming is because they all form three-dimensional repeating patterns. Kiana, can you tell us more about the patterns?

Kiana

Crystals are beautiful and amazing formations that hold many mysteries inside them, but what actually causes them to form? Most people already know that crystals are formed from liquids cooling and hardening, but atoms are actually a very important part of it. In the process of crystallization, atoms link together and form repeating patterns. As more atoms link together, the crystal gets bigger. Different types of atoms will form different patterns and unique shapes. There are seven basic shapes that crystal form: cubic, trigonal, triclinic, orthorhombic, hexagonal, tetragonal, and monoclinic. Every crystal has a distinct pattern of atoms. For example, salt crystals form a cube shape, and snowflakes are six-pointed star-like crystals. Every crystal's size, shape, and structure depend on the atoms present and other conditions, including the amount of heat and pressure present and how deep inside the crust the crystal is forming. Atoms are a key part in crystal formation even though they might not always get the credit.

Student

You're right, Kiana. Those atoms do deserve more credit. The crystals they form can be used in so many different ways. One way is through a crystal oscillator that is found in circuit boards. The crystal oscillator uses the electric charge in the crystal to create an electric signal. These crystal oscillators are what make many of our technological devices work -- like televisions, computer screens, cell phones, and radios. Radios made in the 1890s had quartz crystal in them that helped the radio frequencies reach the listeners. Crystals are also used in wristwatches to keep track of time and compasses because some crystals are magnetic. Crystals are very cool because they are used in a lot of different things and look different in each use. But don't go hunting for crystals in your TV because that will break it. Also you won't actually find any crystals in there because TV screens are made with liquid crystals that technically aren't crystals because they're liquid. Well, in summary, here's Gunnar.

Gunnar

In summary, crystals are any solid or semi-solid that has atoms that are arranged in repeating patterns. The main ways crystals are formed is when magma cools and hardens or when water evaporates. Atoms form repeating patterns that make every type of crystal unique. Crystals have many important uses in our world and have played an important role in the development of technology that most of us use every day.

Dr. Universe

That's a wrap on this episode, friends. Thanks so much for joining us on this special edition of the Ask Doctor Universe podcast featuring fourth grade scientists at Palouse Prairie Charter School.

Student

And a big thanks to Northwest Public Broadcasting for helping us record. And to Dr. Julie Menard at Washington State University for fact checking the science. We are grateful for the helpful and informative resources from NASA, USGS, NOAA, the Smithsonian, and universities all around the world. You can find a list of our resources in the transcript.

Dr. Universe

As always, kids can submit science questions at askdruniverse.wsu.edu. That's a-s-k d-r u-n-i-v-e-r-s-e dot w-s-u. dot e-d-u. Who knows where your questions will take us next.

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Sources

Volcanoes:

NASA