Lava is molten rock expelled from a volcano onto the Earth’s surface, or the cooled rock that results from this process. It is characterized by extremely high temperatures. This molten material, also known as magma when still beneath the surface, can vary in its properties depending on its chemical composition.
Immediate Physical Effects
Direct contact with lava causes immediate and severe physical effects. The extreme heat of molten lava, typically ranging from 700°C to 1200°C (1300°F to 2200°F), instantly causes the water within human cells to vaporize. This rapid vaporization and protein coagulation lead to severe tissue destruction, resulting in third and fourth-degree burns. Skin, muscle, and even bone can be damaged or charred upon contact.
Lava is significantly denser and more viscous than water. A human body would not sink into lava; instead, it would remain on the surface. The intense heat would cause rapid burning and charring. A layer of steam would also form between the body and the lava, further preventing sinking.
The Science Behind Lava’s Danger
Lava’s danger lies in its mechanisms of heat transfer. Temperatures can range from 650°C to 1600°C (1200°F to 2900°F) depending on chemical makeup. This intense heat transfers through radiant, conductive, and convective processes.
Radiant heat, felt from a distance, can cause severe burns even without direct contact. Conductive heat occurs through direct physical contact, transferring heat from the lava. Convective heat involves the movement of superheated gases and air around the lava, which can also cause burns. Lava’s high density, roughly three times that of water, and its viscosity, ranging from 100,000 to over a million times thicker than water, are also factors.
Other Lava Hazards
Beyond direct contact, lava presents additional hazards, primarily from the gases it releases. Volcanic gases, including sulfur dioxide (SO2), carbon dioxide (CO2), and hydrogen sulfide (H2S), are emitted from active lava flows and volcanic vents. Sulfur dioxide can irritate eyes, skin, and the respiratory system, and contribute to volcanic smog. Carbon dioxide, being heavier than air, can accumulate in low-lying areas, potentially causing dizziness, difficulty breathing, unconsciousness, and even death by asphyxiation.
Hydrogen sulfide, known for its rotten-egg smell, is also toxic in higher concentrations. Additionally, hydrogen halides like hydrogen fluoride (HF) and hydrogen chloride (HCl) can be present, causing irritation and forming acid rain. These gases pose a risk even at a distance from the lava flow, affecting air quality and potentially leading to serious health issues.
Dispelling Common Myths
A common misconception, often portrayed in fiction, is that a person would slowly sink into molten lava. As previously explained, lava’s significantly greater density than the human body causes a person to float on its surface. The immediate and extreme heat also rapidly vaporizes the body’s moisture, creating a cushion of steam (the Leidenfrost effect) that further prevents sinking. Contact with lava results in instantaneous tissue destruction and rapid burning on the surface.