Discovery Science: Earth – Thermal Springs and Geysers
Geysers are spectacular and demonstrate the immense energy stored in the interior of the Earth. Similarly, thermal springs, fumaroles, mofettes, and solfataras hint at the dangerous potential of volcanoes.
Geysers are typical features of regions where volcanic activity is abating. They occur only on a few places on Earth: Iceland, the United States, Chile, New Zealand, Japan, Ethiopia, and on the Kamchatka Peninsula. Some regularly eject jets of water or steam up to 320 feet (100 m) high. The water originates from a larger reservoir deep below the surface of the
Earth, where magma heats up the water gradually.
The pressure created by the boiling water causes it to explosively eject through a stack from time to time. The depleted hot water is replaced by cool groundwater, which terminates the process before the cycle starts again. Beauty and health Yellowstone National Park has the largest concentration of thermal springs in the world. The water that flows from the springs, which can be close to boiling point, is enriched with minerals.
These precipitate as soon as the water cools down at the Earth’s surface. This leads to the formation of impressive rock formations. A famous example is the sinter terraces found in Pamukkale (Western Anatolia, Turkey). These thermal springs have been famous for their therapeutic benefits for thousands of years.
Hot steam and toxic gases
Fumaroles are any cracks in the Earth’s surface that emit steam and gases. They are at lower pressure than geysers, so they do not eject any water. Steam and gas from fumaroles can reach temperatures of up to 1470°F (800°C). When these hot gases meet with water upon exiting the ground, they create bubbling mud pots or mud gushers. Solfataras are fumaroles that emit sulfurous gases.
They are usually somewhat cooler, and their emissions settle out next to the ejection points in the form of pure sulfur. The most dangerous of all degassing features are mofettes. Gases escape through small holes and cracks in rocks, delivering high concentrations of toxic carbon dioxide.
BLACK SMOKERS
Black smokers are hot springs at the bottom of the ocean. They were dis- covered in 1977 near the Galapagos Islands at a depth of about 8,500 feet (2.600 m). They eject water as hot as 660°F (350°C) from their chimneylike stacks.
Precipitation from dissolved metallic sulfides produces plumes of black smoke. These thermal springs are fascinating for scientists as communities of living organisms survive in their dark and poisonous surroudings.