Lava is molten rock, called magma, that has been expelled onto the Earth’s surface through a volcanic vent or fissure. Although it is a liquid, its nature is vastly different from water, defying common perceptions seen in movies. Understanding what it feels like to interact with lava requires examining the intense thermal energy it radiates and the unique physical properties of the molten rock itself.
The Overwhelming Sensation of Heat
The primary sensory experience near an active lava flow is the profound, searing heat, not the visual sight of the liquid rock. This sensation is caused by thermal radiation, the transfer of energy via electromagnetic waves, mainly in the infrared spectrum. Freshly erupted basaltic lava flows at temperatures around 1,200 degrees Celsius, causing a massive release of radiant energy.
The intensity of this heat drops off rapidly with distance, following the inverse square law. If you double your distance from the lava, the radiant heat you feel is reduced to one-fourth of its original intensity. While this quick dissipation allows observers to stand relatively close, the sensation is still overwhelming, and the surrounding air feels searingly hot. This intense energy can cause severe burns almost instantly, making any close approach dangerous even without direct contact.
Understanding Lava’s Consistency
Lava has a consistency unlike any common liquid, primarily due to its high viscosity and density. Viscosity measures a fluid’s resistance to flow, and even the most fluid basaltic lava is tens of thousands of times more viscous than water. This causes the molten material to move with a thick, syrupy quality, akin to wet concrete or very dense, slow-moving tar.
The appearance of lava depends on its flow type, which relates to its viscosity and temperature. Pāhoehoe lava, which is hotter and less viscous, forms a smooth, ropey surface texture as it cools. The chunkier, more brittle ‘A’ā lava is slightly cooler and more viscous, breaking into jagged, blocky fragments as it moves.
Lava is also remarkably dense, with a density of approximately 3,100 kilograms per cubic meter, about three times that of water. This density means most organic materials and objects that fall onto it will not sink but will rest on the surface. The high viscosity further contributes to the difficulty of penetrating the molten rock.
What Happens When Objects Make Contact
Touching lava is not a tactile experience but an immediate, irreversible physical and chemical reaction. Any object with significant moisture, like a human hand or wood, instantly triggers the vaporization of water upon contact with the extreme heat. Since the human body is largely composed of water, this sudden phase change creates explosive pockets of steam and gas.
Due to the lava’s high density, a human would float rather than sinking into the molten rock, but the extreme heat causes immediate combustion of organic material. The intense thermal shock and vaporization of moisture prevent any sensation of texture, replacing it with an instantaneous burst of heat and a violent disruption of the lava’s surface.