Dallol Hydrothermal Field
Once a month here on the Molten Sulfur Blog, I run content taken from our book Archive: Historical People, Places, and Events for RPGs. This post, about the Dallol Hydrothermal Field in Ethiopia, is one of eighty entries in Archive, each more gameable than the last!
You can get Archive as an add-on in our ongoing Kickstarter campaign, which has only a week left! Check out Making History: Three One-Session RPGs!
Image credit: Ji-Elle, released under a Creative Commons Attribution 3.0 Generic license
Dallol Hydrothermal Field
A Neon Hell
The Dallol Hydrothermal Field in northeast Ethiopia is one of the most colorful and lifeless places on Earth. It’s also one of the hottest, with an average daily high of 106 ̊F, and an annual average temperature of 94 ̊F . It is a barren land, devoid of life, yet there are occasional bodies of dead birds and grasshoppers littering the area. During the rainy season, the craters fill with runoff. This water, and seemingly everything else around, simmers and boils like a witch’s cauldron.
The Dallol Hydrothermal Field is in the northern area of the Danakil Depression, which is covered by salt flats, basalt flows, shield volcanoes, and cinder cones. Craters up to a mile across mark the flats, thought to be formed by phreatic eruptions. These types of eruptions occur when magma heats ground or surface water to such extreme temperatures that liquid in the area instantly evaporates, causing a sudden explosion of steam to erupt from the ground, leaving a crater in its wake. The most recent phreatic eruption was in 1926, when magma climbed towards the surface and breached the salt crust. This eruption created a small crater around 100 feet across.
Every day in the Dallol, magma flowing under the earth heats groundwater. The heat makes the water climb up towards the surface, dissolving the salt and other soluble minerals it encounters. The brine rises through hot springs in the crater floor, and when it evaporates, salt formations crystallize in a variety of bright colors: white, yellow, pink, red, orange, and green, the colors due to sulfur, dissolved iron, mud, and the activity of halophile algae. Some of the salt deposits are black, brown, and gray, contrasting against the neon mounds. These deposits give the dangerous area a vibrant atmosphere.
The treacherous areas lie mostly in the craters of the Dallol, where some of the surfaces are only a thin salt crust over boiling acidic water. Occasionally, the craters release toxic gases, and though the volcanic system under the Dallol has been calm for 90 years, it is still an unpredictable, active system. All of this on top of the severe climate and no fresh water.
Dallol Hydrothermal Field in Play
At the table, the Dallol Hydrothermal Field could be an interesting survival situation for your PCs. Perhaps the Dallol is an area where exiles are sent to suffer, which the PCs have to traverse in search of a particular item or person. The Dallol offers hot springs, brine pools, multi-colored sand deposits, miniature geysers, and the occasional naturally-hidden acidic pool for your PCs to find themselves treading through. Imagine a combat encounter taking place in an area where volcanic activity could stir up beneath your feet, where phreatic eruptions could create treacherous obstacles, and where the daily heat can drive you delirious. In a fantasy campaign, the area could be hellish enough for demons to roam free. Maybe some of the craters hide portals to hell for either the PCs to leap through or devils to crawl up through. With the bright neon features and the crusty, porous mounds spouting up over the horizon, the Dallol could make for a fantastic alien landscape.