A geyser is a natural spring characterized by the intermittent, turbulent discharge of a column of superheated water and steam. This rare phenomenon occurs when groundwater seeps into the Earth’s crust and contacts hot, subsurface rock, resulting in a pressurized hydrothermal system. While beautiful, a geyser basin is an unpredictable and volatile landscape that poses multiple severe risks to visitors.
The Hazard of Superheated Water and Steam
The water that fuels a geyser is heated by magma close to the Earth’s surface, reaching temperatures far exceeding the standard boiling point of 100°C (212°F). This superheating is possible because the immense pressure from the overlying water column prevents the liquid from turning into steam. Water deep within the geyser’s plumbing can sometimes reach temperatures between 160°C and 180°C (320°F and 356°F) before an eruption.
When enough heat and pressure build up, the weight of the water column is momentarily reduced, often when a small amount of water flashes to steam near the top. This pressure release causes the superheated water below to instantly and violently flash into steam, triggering the dramatic eruption. This rapid transformation is dangerous because steam occupies approximately 1,600 times the volume of the original water, resulting in an explosive force.
Contact with the scalding water and high-temperature steam ejected during an eruption can cause immediate and catastrophic third-degree burns. These injuries can occur in seconds and cover a large surface area, leading to severe trauma or fatality. The steam itself, which is often invisible before it condenses into a visible vapor cloud, carries a tremendous amount of thermal energy.
Ground Instability and Thin Crusts
The most deceptive hazard in a geyser basin is the ground itself, which is often a fragile thermal crust concealing scalding water just beneath the surface. Geothermal heat and the acidic nature of the circulating hot water chemically alter the underlying rock and soil. This process breaks down the geological structure, creating a thin, unstable layer that can appear solid and safe.
This deceptively firm ground is incapable of supporting the weight of a person. Stepping off a designated path can result in a sudden breakthrough and immediate immersion into the superheated water and mud below, causing severe burns or death. These geothermal landscapes are constantly shifting, with the location of thermal features and weak crusts changing unpredictably over time.
The structural fragility means that even areas without visible hot springs or geysers may be hollow or unstable due to subsurface hydrothermal activity. Sinter, the mineral deposit left behind by geyser water, contributes to the appearance of solid rock but does not guarantee stability.
Risk of Geothermal Gas Emissions
Geothermal areas naturally vent gases released from the subsurface, creating an invisible, atmospheric hazard. The two most prominent gases emitted are hydrogen sulfide (\(\text{H}_2\text{S}\)) and carbon dioxide (\(\text{CO}_2\)). Both gases pose a serious threat to human health, even in small concentrations.
Hydrogen sulfide is highly toxic and corrosive, recognizable by its distinct “rotten egg” smell. While the odor serves as a warning at low concentrations, prolonged exposure or higher concentrations quickly deaden the sense of smell. This makes the gas undetectable before it causes respiratory distress or poisoning, and concentrations near vents can present an acute respiratory hazard.
Carbon dioxide poses a danger because it is denser than air. This characteristic causes the gas to pool in low-lying areas, depressions, or confined spaces, effectively displacing breathable oxygen. Entering an area where \(\text{CO}_2\) has accumulated can lead to rapid asphyxiation without any initial warning signs.
Essential Safety Guidelines for Visitors
Mitigating the dangers of geysers requires strict adherence to established safety protocols designed to manage the known risks of these volatile environments. Venturing off designated pathways is the primary cause of accidents in geothermal areas.
Visitors must follow these essential safety guidelines:
- Always remain on marked trails and boardwalks, which are constructed to provide safe viewing distances and stable ground.
- Obey all posted park signage, as warnings indicate localized hazardous conditions like high temperatures or fragile ground.
- Maintain a distance of at least 25 feet (8 meters) from all thermal features, including hot springs and fumaroles.
- Never attempt to touch the water, test the temperature, or throw objects into any geothermal feature, as this can trigger unpredictable eruptions or damage subterranean plumbing.
- Keep a close watch on children and pets to prevent accidental contact with hazardous features and unstable terrain.