What Is Lava Tube? (Definition, Formation, Example)

What is lava tube

A lava tube is a natural geological formation that occurs when lava flows from a volcanic eruption and creates a tunnel-like structure. It forms when the outer surface of a lava flow cools and solidifies while the molten lava inside continues to flow, eventually draining out. As a result, a hollow tube or tunnel is left behind. Lava tubes typically occur in basaltic volcanic regions, where the lava has a low viscosity and can flow more easily. They are commonly found in areas with extensive volcanic activity, such as fields or shield volcanoes.

Dive deep into the shadowy realms beneath the earth’s crust, where the enigmatic world of lava tubes awaits. These subterranean tunnels, carved by the flow of molten rock, offer a rare glimpse into the dynamic forces that sculpt our planet from within. Embark on a journey to uncover the secrets of these hidden geological formations, exploring their creation, significance, and the mysterious ecosystems they harbor.

What Is Lava Tube?

Lava tubes are exciting volcanic features. When that lava moves down the slope, its outer portions will cool below and above it, creating 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 flows into the landscape’s low areas as it goes down the slope. The flowing lava is about 2,000 degrees Fahrenheit, which is incredibly hot. But when it’s at the surface exposed to the open air, it cools and hardens from the outside reasonably quickly. The lava flow will create a channel, like a river in the wintertime. The channel will crust or freeze from the outer edges towards the middle.

Once the channel is wholly crusted, the over-temperature loss is minimal over travel miles. At this early stage in the formation, the tube is relatively wide, shallow, and has a thin crust. Increasing lava from 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 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 melt the walls and the ceiling, creating soda straw stalactites. And other unique formations are only found in lava tubes.

Lava tube diagram
Lava tube diagram

These delicate structures are only formed in a tube with 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 flow 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, 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 some places where you can find these huge lava tubes.

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

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

What is Lava Tube in Geography?

A lava tube is a natural geological formation found in volcanic terrains, formed during the eruption of fluid lava flows. These tubes are essentially long, hollow tunnels through which lava travels beneath the surface of a lava flow. The formation of lava tubes plays a significant role in how volcanic eruptions unfold and in shaping the landscape around volcanoes. Here’s how they form and their characteristics:

Formation Process

Initial Flow: A lava tube starts to form when a channel of fluid lava begins to flow beneath the hardened surface of a lava flow. As the surface of the flow cools and solidifies, it insulates the underlying lava, keeping it hot and fluid.
Crust Formation: The top layer of the lava stream cools when it is exposed to the air, forming a solid crust. This crust thickens and eventually forms a roof over the flowing lava.
Tunnel Development: Beneath this solidified crust, the lava continues to flow and can maintain its liquidity and high temperature due to the insulating effect of the surrounding solid lava. Over time, if the supply of lava diminishes or stops, the molten lava may drain out, leaving behind an empty tube.
Tube System: Lava tubes can be complex, with branches, side tubes, and chambers, depending on the flow dynamics, the terrain, and changes in the eruption’s intensity.

Characteristics and Importance

Insulation: The formation of lava tubes allows the lava to travel great distances from the volcano without significant cooling. This is because the tube insulates the lava from the cooler outside air, preventing it from solidifying quickly.
Surface Protection: Lava tubes can help protect the surface over which the lava flows from extensive damage, as most of the lava is contained and transported underground.
Cave Ecosystems: Once a lava tube is emptied of lava and cools, it can form a cave. These caves can provide unique habitats for organisms and are of interest to biological studies.
Tourism and Education: In many places, lava tubes have become accessible to tourists and serve as significant educational sites where people can learn about volcanic processes and the geology of lava flows.
Speleology and Research: Lava tubes interest speleologists (cave scientists) and geologists studying their formation, structure, and role in volcanic activity and landscape evolution.

What Is Lava Tube For Kids?

A lava tube is like a secret tunnel made by flowing lava from a volcano. Imagine when a volcano erupts, and lots of hot, liquid rock called lava flows out. This lava can flow over the ground like a very hot river. But sometimes, something cool happens. The top layer of this lava river starts to cool down because it touches the air, and it gets hard and crusty, like the top of a brownie when it cools after baking. But underneath this hard top, the lava is still hot and flowing like nothing happened.

Over time, the hot lava underneath keeps moving and leaves behind a hard, crusty top, creating a big tunnel. This tunnel is what we call a lava tube. It’s like a natural underground passage where lava used to flow. Once all the lava flows out and leaves the tube, it becomes an empty cave.

These lava tubes really long and sometimes have branches, like a maze underground. After the lava is all gone and the tube cools down, animals or plants start to live there, or people can explore them like a big natural adventure playground. It’s one of the many amazing and cool things volcanoes can create!

Lava Tube Features

Lava tubes, natural tunnels, or conduits formed by flowing lava can exhibit various features. Here are some common features associated with lava tubes:

Entrance and Exit: Lava tubes have distinct openings through which the lava initially enters and exits the tube. These points serve as the entry and exit points of the flowing lava and are usually found on a volcano’s flanks or lower slopes.

Tube Shape and Size: Lava tubes can have different shapes and sizes. They can be round, elliptical, or irregular in cross-section. The size of a lava tube can range from small and narrow tubes to larger, more expansive ones, depending on the volume and duration of the lava flow.

Roof/Ceiling: The roof or ceiling of a lava tube is typically arched or curved due to the fluid movement of the lava. It is formed by the solidification of the lava flow’s upper surface. The roof can vary in thickness; in some cases, it may have collapsed, creating openings known as skylights.

Walls: The walls of a lava tube are made up of solidified lava, resulting from the cooling and hardening of the lava flow. The walls can range from smooth and glassy surfaces to rough and jagged textures, depending on the cooling conditions and the type of lava that formed them.

Floor: The floor of a lava tube is the bottom surface formed by the solidified lava flow. It can be relatively flat or uneven, depending on the topography over which the lava flows. Sometimes, the floor may have channels or grooves carved by the flowing lava.

Skylights: Skylights are openings or windows in the roof of a lava tube. They occur when sections of the roof collapse or erode, providing access to natural light from above. Skylights can range from small openings to larger apertures that allow more light to enter the lava tube.

Lava Stalactites and Stalagmites: Over time, dripping or splashing lava can form stalactites and stalagmites inside lava tubes. These features resemble those found in caves, with stalactites hanging from the ceiling and stalagmites rising from the floor. They are composed of solidified lava deposits.

Secondary Tubes and Branches: Lava tubes can sometimes exhibit secondary tubes or branches that connect to the main tube. These secondary passages may form due to variations in lava flow direction or changes in the tube’s structure.

Lava Tube

As we conclude our exploration of lava tubes, we emerge with a newfound respect for the complex and vibrant tapestry of Earth’s interior landscape. These natural wonders not only provide fascinating insights into volcanic activity but also challenge us to consider the delicate balance of life in the most unexpected places. The journey through the dark, winding passages of lava tubes leaves us with a deeper appreciation for the planet’s untamed beauty and the endless mysteries waiting to be discovered beneath our feet.


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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