Science Facts

What Is Lava Tube? – Definition, Formation & Example

Lava Tube

My name is Scott, your geologist. We’re going to be talking about lava tubes and how they’re formed. Lava tubes are created by the channel of lava-like the Hawaiian Kilauea eruption. It was created like a river of lava and started to crust over.

What is lava tube?

Lava tubes are exciting volcanic features. When that lava moves down the slope, its outer portions will cool below it, above it, and create a hard layer of rock called basalt. It’s still hot and flowing on the inside, and that red-hot lava flows out of the hardened top, bottom and leaves a hollow space in the middle.

Lava tends to flow into the landscape’s low areas as it makes its way down the slope. The flowing lava is about 2,000 degrees Fahrenheit which is incredibly hot.

But when it’s here at the surface exposed to the open air, it cools and hardens from the outside reasonably quickly. The lava flow will start to create a channel, just like a river in the wintertime. The channel will begin to crust or freeze over from the outer edges towards the middle.

Once the channel is wholly crusted, the over-temperature loss is minimal over miles of travel. At this early stage in the formation, the tube is relatively wide shallow, and thin crust. Increasing lava coming through the tube could cause surface breakouts from the ceiling flowing over the tube system and thickening the crust.

The lava flowing through the tube will thermally erode the floor and cut just like a 2,000-degree river. With increased down-cutting, the tube will enlarge.

The lava flow will only be possibly midway, and above it will be a section of superheated gas and air. Also, The lava’s intense heat inside the tube will remelt the walls and the ceiling creating soda straw stalactites. And other unique formations are only found in lava tubes.

These delicate structures are only formed in a tube that has an active flow. After the eruption stops, the tube system will drain out reasonably quickly. Leaving us with a truly fantastic creation of nature that will soon develop, and it’s an ecosystem of its own. The geologic features inside a tube only form when there’s an active flow.

  • Lava comes in contact with the air, and it hardens into rock. Usually, within the river, where it’s being taken away but along the riverbank, you get a little accumulation of crossing over time. It can come together and form a roof over the river. Then lavas flowing underground, and that’s how the lava tubes are formed.

When this lava splashes into the cool ocean water, it solidifies rapidly, forming what is known as an extrusive igneous rock. The resulting rock will cool so quickly that crystals will not have the opportunity to form, and as such, the rock will have a glassy texture. Additionally, there will likely be trapped air bubbles or gas pockets, making it a vesicular texture.

Lava tubes are formed in the Coconino National Forest, and they’re composed of a rock called basalt. Basalt is a rock that has about fifty percent silica. Also, It’s very fluid lava, and it flows downhill readily. Most of the lava tube’s source is a volcanic eruption.

Example: If you go to Lanzarote, Hawaii, Iceland, Queensland, Australia, and Sicily, these are just some of the places where you can find these huge lava tubes.

You can get these things called inflator tubes, which are very deep down, and the lava gets injected into these fissures from previous tubes. It causes massive swelling and a massive expansion to form these huge underground caverns.

These lava tubes that you find on Earth, Mars, and that you can find on the moon. The weaker the gravity, the bigger the lava tubes you find.


Dutton, C. E., “Hawaiian volcanoes.” Annual Report U.S. Geological Survey.
Macdonald, Gordon A.; Abbott, Agatin T.; Volcanoes in the sea: the geology of Hawaii (2nd ed.). Honolulu: University of Hawaii Press.
McGounis-Mark, Peter. “Radar Studies of Lava Flows.” Volcanic Features of Hawaii and Other Worlds. Lunar and Planetary Institute.
Volcano, Costa Rica”. Journal of Volcanology and Geothermal Research.

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