10 Interesting Facts About Volcanoes

Want some volcano facts? Here are 10 interesting facts about volcanoes. Some of these facts you’ll know, and others may surprise you. Whatever the case, volcanoes are amazing features of nature that demand our respect.

1. There are Three Major Kinds of Volcanoes:

Although volcanoes are all made from hot magma reaching the surface of the Earth and erupting, there are different kinds. Shield volcanoes have lava flows with low viscosity that flow dozens of kilometers; this makes them very wide with smoothly sloping flanks.

Stratovolcanoes are made up of different kinds of lava, and eruptions of ash and rock and grow to enormous heights. Cinder cone volcanoes are usually smaller, and come from short-lived eruptions that only make a cone about 400 meters high.

2. Volcanoes Erupt Because of Escaping Magma:

About 30 km beneath your feet is the Earth’s mantle. It’s a region of superhot rock that extends down to the Earth’s core. This region is so hot that molten rock can squeeze out and form giant bubbles of liquid rock called magma chambers. This magma is lighter than the surrounding rock, so it rises up, finding cracks and weakness in the Earth’s crust.

Lava fountain in Hawaii.
Lava fountain in Hawaii. Image Credit: Jim D. Griggs/HVO/USGS

When it finally reaches the surface, it erupts out of the ground as lava, ash, volcanic gasses and rock. It’s called magma when it’s under the ground, and lava when it erupts onto the surface.

3. Volcanoes can be Active, Dormant or Extinct:

An active volcano is one that has had an eruption in historical times (in the last few thousand years). A dormant volcano is one that has erupted in historical times and has the potential to erupt again, it just hasn’t erupted recently. An extinct volcano is one that scientists think probably won’t erupt again. Here’s more information on the active volcanoes in the world.

4. Volcanoes can Grow Quickly:

Although some volcanoes can take thousands of years to form, others can grow overnight. For example, the cinder cone volcano Paricutin appeared in a Mexican cornfield on February 20, 1943. Within a week it was 5 stories tall, and by the end of a year it had grown to more than 336 meters tall. It ended its grown in 1952, at a height of 424 meters. By geology standards, that’s pretty quick.

Detailed View of Ash Plume at Eyjafjallajökull Volcano
Detailed view from space of the ash plume caused by the Eyjafjallajökull volcano in 2010. Credit: NASA

5. There are 20 Volcanoes Erupting Right Now:

Somewhere, around the world, there are likely about 20 active volcanoes erupting as you’re reading this. Some are experiencing new activity, others are ongoing. Between 50-70 volcanoes erupted last year, and 160 were active in the last decade. Geologists estimate that 1,300 erupted in the last 10,000 years.

Three quarters of all eruptions happen underneath the ocean, and most are actively erupting and no geologist knows about it at all. One of the reasons is that volcanoes occur at the mid ocean ridges, where the ocean’s plates are spreading apart. If you add the underwater volcanoes, you get an estimate that there are a total of about 6,000 volcanoes that have erupted in the last 10,000 years.

6. Volcanoes are Dangerous:

But then you knew that. Some of the most deadly volcanoes include Krakatoa, which erupted in 1883, releasing a tsunami that killed 36,000 people. When Vesuvius exploded in AD 79, it buried the towns of Pompeii and Herculaneum, killing 16,000 people.

Image of Mt. Vesuvius, captured in 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Credit: NASA/EO
Image of Mt. Vesuvius, captured in 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. Credit: NASA/EO

Mount Pelee, on the island of Martinique destroyed a town with 30,000 people in 1902. The most dangerous aspect of volcanoes are the deadly pyroclastic flows that blast down the side of a volcano during an eruption. These contain ash, rock and water moving hundreds of kilometers an hour, and hotter than 1,000 degrees C.

7. Supervolcanoes are Really Dangerous:

Geologists measure volcano eruptions using the Volcano Explosivity Index, which measures the amount of material released. A “small” eruption like Mount St. Helens was a 5 out of 8, releasing a cubic kilometer of material. The largest explosion on record was Toba, thought to have erupted 73,000 years ago.

It released more than 1,000 cubic kilometers of material, and created a caldera 100 km long and 30 kilometers wide. The explosion plunged the world into a world wide ice age. Toba was considered an 8 on the VEI.

8. The Tallest Volcano in the Solar System isn’t on Earth:

That’s right, the tallest volcano in the Solar System isn’t on Earth at all, but on Mars. Olympus Mons, on Mars, is a giant shield volcano that rises to an elevation of 27 km, and it measures 550 km across. Scientists think that Olympus Mons was able to get so large because there aren’t any plate tectonics on Mars. A single hotspot was able to bubble away for billions of years, building the volcano up bigger and bigger.

Mauna Kea
Mauna Kea observed from space. Credit: NASA/EO

9. The Tallest and Biggest Volcanoes on Earth are side by side:

The tallest volcano on Earth is Hawaii’s Mauna Kea, with an elevation of 4,207 meters. It’s only a little bigger than the largest volcano on Earth, Mauna Loa with an elevation of only 4,169 meters. Both are shield volcanoes that rise up from the bottom of the ocean. If you could measure Mauna Kea from the base of the ocean to its peak, you’d get a true height of 10,203 meters (and that’s bigger than Mount Everest).

10. The Most Distant Point from the Center of the Earth is a Volcano:

You might think that the peak of Mount Everest is the most distant point from the center of the Earth, but that’s not true. Instead, it’s the volcano Chimborazo in Ecuador. That’s because the Earth is spinning in space and is flattened out. Points at the equator are further from the center of the Earth than the poles. And Chimborazo is very close to the Earth’s equator.

We have written many articles about volcanoes for Universe Today. Here’s an article that tackles about the 10 facts about earth’s core. You might also want to read on the 10 facts about earth. And here’s more: all about volcanoes.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

USGS Volcano Hazards Program

Yellowstone National Park Volcano

Yellowstone National Park is known for its geysers, but did you know that it is also the site of one of the world’s largest volcanoes? The same geologic activity that causes the multitude of geysers in the park is also responsible for the huge volcano located there. Scientists estimate that it is one of the largest volcanoes in the world, and so far it is the largest volcano in North America.

The volcano is 55 km by 72 km in size. Yellowstone’s volcano is in the class of super volcanoes due to its size. There is no exact definition for what qualifies as a super volcano; however, some scientists have defined it as a volcano with an eruption greater than 240 cubic miles.

Additionally, the Yellowstone Volcano does not look like the popular image of a volcano. Instead of being a conical mountain, it is a large depression in the ground like a cauldron. This type of volcanic feature is known as a caldera. It is very difficult to see the actual shape because it is covered with trees and has eroded over thousands of years.

Yellowstone National Park sits on top of a giant volcanic caldera, or an earthen cap that covers a huge reservoir of superhot liquid rock and poison gasses. Credit: IO9
Yellowstone National Park sits on top of a giant volcanic caldera, or an earthen cap that covers a huge reservoir of superhot liquid rock and poison gasses. Credit: IO9

The cause of the volcano is the hotspot on which Yellowstone is located. At a hotspot, molten mantle rock tends to rise toward the surface causing different geological activity. Volcanic eruptions from the hotspot also helped form the Snake River Plain.

Not only do volcanic eruptions occur around the Yellowstone region, but the area also experiences many earthquakes. The region experiences around 1000 to 2000 earthquakes each year, although most of them are usually quite small.

Despite the fact that the volcano has not erupted in hundreds of years, it is still active. This is a concern to scientists who have placed sensors around Yellowstone, so the volcano is continually monitored. The possible eruption of the Yellowstone Super volcano is of concern because of the enormous destruction it would cause. The last eruption was believed to be approximately 640,000 years ago.

Geologists estimate that 2 million years ago a cataclysmic series of volcanic eruptions in the Yellowsone Caldera was 2,500 times more powerful than the Mt. St. Helens eruption and perhaps was the largest, most violent volcanic eruption in the history of earth. Credit: Extreme Science
Geologists estimate that 2 million years ago a cataclysmic series of volcanic eruptions in the Yellowstone Caldera was perhaps the most violent volcanic eruption in the history of earth. Credit: Extreme Science

The eruption was on such a scale that it made the 1980 Mount St. Helen’s eruption look like nothing and result in damage and destruction many miles around. Scientists estimate that the other two eruptions from the Yellowstone Super volcano came over one and two million years ago. Since the volcano is still active, there is always a possibility it will once again erupt.

However, scientists do not anticipate that there will be another eruption in the near future, at least one on such a massive scale.

Universe Today has articles on Yellowstone eruption and Yellowstone Super Volcano.

For more information, try Yellowstone Volcano and Supervolcano.

Astronomy Cast has an episode on volcanoes hot and cold.