Since I just finished a great vacation in Yellowstone National Park, here is a brief section on natural hazards associated with geothermal areas. You often see signs in Yellowstone that say “stay on the path”, and for good reason. The ground surface may look solid, but areas are less than an inch think before you crunch into scalding hot water. This water may be inches deep or tens of feet deep. If you are lucky, you get severe burns on a limb. Less lucky…being burnt to death is a pretty painful way to kill off a character. Areas like Yellowstone with geysers and hot springs are rare around the world (about half the known geysers are in Yellowstone), and they are great for games because of that uniqueness.
Geothermal systems are places where the earth is hotter than surrounding areas, due to the presence of magma heating up rock near the earth’s surface. Geothermal areas are found near volcanoes (active or inactive) and mountain ranges where there is plenty of groundwater. Most are near the Ring of Fire around the Pacific Ocean.
Geothermal hazards include:
- scalding hot water (hot springs)
- geyser eruptions
- boiling mud (mudpots)
- geothermal chemicals and bacteria in water
- steam and other gases
- geothermally altered ground (weakened soil and rock)
Characters familiar with the area will be able to identify these hazards and be able to avoid them. But for most characters, this will be a new and strange landscape.
Small mounds of silica other minerals suddenly burst into unpredictable geysers. These can be short bursts of boiling water and steam or hundreds of feet of gas and water lasting for quite a few minutes. On the other hand, mudpots and hot springs are obvious as pools of bubbling water and mud. But when a character walks over to get a drink or get a closer look at the brilliant colors from the specialized bacteria that live in the hot water, they may break through the mineral crust and burn themselves. If they walk on solid ground and get a drink of water, the bacteria and dissolved chemicals can make them seriously ill. Rotten eggs is a common smell in this environment, but sometimes there is more than sulfur being released into the air.
Earthquakes, landslides, and removing or adding groundwater can change or destroy the mechanics that creates geothermal hazards. So in modern or futuristic games, you can play out destroying a geyser field by drilling or injection wells. In any game an earthquake can be the death of old hot springs and the birth of new ones. Moving geothermal features can kill a section of forest that was growing, leaving a creepy wasteland of dead trees for your next horror game. Play with it and have fun.