Lava tube

A lava tube is a natural conduit formed by flowing lava from a volcanic vent during an effusive eruption. These tubes are typically cave-like structures, but they are formed by the cooling and solidifying of the lava's outer surface while molten lava continues to flow within. Once the eruption ceases and the lava supply is cut off, the molten lava drains away, leaving behind a hollow, tunnel-like space.

Lava tubes form in two primary ways:

• Roofing-over of an open channel: Lava flows often begin as open channels. As the lava cools along the edges and surface, a crust forms. If this crust gradually thickens and covers the entire channel, it creates a lava tube.

• Inflationary tubes: In some cases, lava tubes form within a lava flow itself. A slightly cooled, but still pliable, flow can inflate as more lava is injected beneath the surface. This inflation creates a cavity that expands into a tube.

Lava tubes can be found in various sizes, ranging from a few meters to tens of meters in diameter, and can extend for several kilometers in length. They are often found on shield volcanoes and in areas with fluid basaltic lava flows, such as Hawaii, Iceland, and the Galapagos Islands. Similar features have also been identified on the Moon and Mars, suggesting volcanic activity on those celestial bodies.

The interior of a lava tube can be characterized by smooth walls, solidified lava formations (such as lava stalactites and lava benches), and remnants of the lava flow that once filled the tube. They provide excellent insulation, keeping the interior temperature relatively constant and protected from external weather conditions. This stable environment makes lava tubes of interest to astrobiologists looking for potential habitats for life on other planets. They also serve as important conduits for subsequent lava flows and can play a significant role in the overall structure and evolution of volcanic landscapes.