July 20, 2004
This photo, taken in last month in Iceland, shows the Strokkur Geyser just before it erupted. The bulging hemisphere of water has a core of steam bubbles (opaque mass in the center of the bulge) that was generated deep within the fissure from which the geyser erupts. Geysers occur in association with areas of volcanic activity. Ground water is heated to the boiling point by geothermal energy and is constricted from circulating to the surface by overlying mineralized rock and the weight of the water column itself. At some point, a critical pressure is reached, and the boiling water is forced upwards, erupting at the ground surface. Although Iceland has few natural resources, hot springs and geysers are used as a source of geothermal energy and are popular tourist attractions as well. Approximately 85 percent of Iceland's nearly 300,000 inhabitants use geothermal energy to heat their homes. See also the EPOD for September 19, 2000.