Volcanic burns are a unique category of trauma, distinct from common household injuries due to the combination of extreme temperatures and corrosive chemical agents. These complex injuries result from immediate exposure to materials ejected during an eruption, including molten rock, superheated water vapor, and highly acidic compounds. The resulting damage to human tissue is often severe, characterized by full-thickness destruction. The appearance of the injury reflects the mechanism of heat or chemical transfer that occurred during exposure.
The Diverse Agents of Volcanic Thermal Injury
The presentation of a volcanic burn is dictated by the physical and chemical properties of the causative agent. Molten lava, which can reach over 1150°C, transfers heat primarily through conduction and intense radiation. This extreme thermal energy rapidly denatures proteins and desiccates tissue, leading to deep, destructive injuries.
Superheated steam and hydrothermal fluids are an equally dangerous hazard, transferring moist heat more efficiently than dry air and causing rapid, deep scalding. Pyroclastic flows, which are fast-moving currents of gas and rock fragments, combine mechanisms by delivering dry heat and high-velocity trauma. Volcanic gases, such as sulfur dioxide, introduce a chemical component, forming strong acids that corrode tissue upon contact. These varied sources result in a spectrum of destructive effects rather than a single type of burn.
Direct Contact Burns from Molten Lava
Burns caused by direct contact with molten lava or solid rock within a pyroclastic flow result in the most rapid and complete destruction of tissue. The immense conductive heat instantly causes full-thickness injuries, often classified as fourth-degree burns that extend into muscle and bone. Visually, the primary characteristic is carbonization, where the tissue is incinerated and reduced to a blackened, brittle state.
This extreme heat causes rapid desiccation, leaving behind a thick, leathery layer of dead tissue known as eschar, which often appears white or waxy. Because the heat destroys nerve endings immediately, there may be little to no pain sensation at the site of the deepest injury, which is a deceptive sign of severity. Injuries from conductive heat are typically deep and localized, exhibiting a distinct demarcation where the molten material touched the body.
Injuries from Steam, Ash, and Acidic Gases
Burns from steam, ash, and acidic gases display a different and often more widespread pattern of injury across the body. Superheated steam and hydrothermal events cause deep scalds, which may initially appear moist, red, and intensely blistered, indicating deep partial- or full-thickness damage. These injuries are deceptive because the moist heat penetrates tissue quickly, creating widespread burns that often require significant skin grafting. Hot ash and tephra result in dry, deep burns that can be patchy or speckled in appearance on exposed skin.
Victims of ash and gas events often arrive smelling strongly of sulfur, with debris embedded in the wounds. Internally, the inhalation of hot ash and gases causes severe respiratory tract burns, leading to inflammation and mucosal sloughing. Volcanic acidic gases, such as hydrogen halides and sulfur dioxide, dissolve in moisture on the skin to form strong acids, causing chemical burns. These corrosive injuries appear as areas of necrosis, characterized by gray or brown discoloration where contact occurred. Strong acids cause coagulation necrosis, resulting in a firm, dry, and sometimes black eschar that is visually distinct from the moist blisters of a steam scald.