Mud Pools
Just off the road to Krýsuvík is a solfatara field at Seltún, Iceland which contains mud pools, acidic hot springs; fumaroles and steaming ground. Fumaroles in the area deposit sulfur and sulphates on the ground near the vents. Fumaroles whose steam is rich in sulfur are called solfataras. The main sulphur area is a fumarole field that lies southwest of the boardwalk at Seltún but sulfur and sulphates around some of the steam vents, mud pools and acidic hot springs were visible to us as we strolled along the boardwalk.
Seltún is part of the large Krýsuvík Geothermal field which lies on one of the NE-SW trending volcanic systems that cross the Reykjanes Peninsula. The volcanic zones lie in the middle of the fissure zone on the Mid-Atlantic Ridge which traverses Iceland and are visible along the south of Reykjanes.
In the mid-20th century there were plans to develop the geothermal field for utilization, including power production, and Seltún then became one of the main drilling targets. There are old drill pads to be seen near the path along the creek. According to the Iceland Geosurvey (ISOR) one of the "boreholes started erupting intermittently in the winter of 2010". They reported that an interval of a few days between the eruptions. We found the spot but on two different visits to the field I saw no sign of geyser activity. ISOR also reports "another old borehole blew up in 1999 forming a crater with a diameter of about 30 m, now filled by mud except where a flow of steam keeps boiling pits open". That unexpected explosion in 1999 reportedly caused the geothermal project to be halted. The springs have been preserved due to the lack of drilling and geothermal exploitation.
Temperatures are over 200 degrees C just below the surface. Geologist from the Iceland Geosurvey believe "the water of the pools is surface water heated by steam from a boiling geothermal reservoir. Accompanying gases such as hydrogen sulphide and carbon dioxide acidify the water and alter the rock to clay. Only the uppermost 300 m of the reservoir at Seltún is boiling, i.e., follows the boiling curve in accordance with increasing pressure. Below this depth, a temperature inversion occurs, indicating that the boiling section is fed laterally from an upflow some distance away.”
The geothermal field is located in the Reykjanes Geopark.
Geologic and geothermal info from Iceland GeoSurvey (ISOR) . Some text in the caption from their web page at: www.geothermal.is/17-seltun-high-temperature-area-solfataras
Mud Pools
Just off the road to Krýsuvík is a solfatara field at Seltún, Iceland which contains mud pools, acidic hot springs; fumaroles and steaming ground. Fumaroles in the area deposit sulfur and sulphates on the ground near the vents. Fumaroles whose steam is rich in sulfur are called solfataras. The main sulphur area is a fumarole field that lies southwest of the boardwalk at Seltún but sulfur and sulphates around some of the steam vents, mud pools and acidic hot springs were visible to us as we strolled along the boardwalk.
Seltún is part of the large Krýsuvík Geothermal field which lies on one of the NE-SW trending volcanic systems that cross the Reykjanes Peninsula. The volcanic zones lie in the middle of the fissure zone on the Mid-Atlantic Ridge which traverses Iceland and are visible along the south of Reykjanes.
In the mid-20th century there were plans to develop the geothermal field for utilization, including power production, and Seltún then became one of the main drilling targets. There are old drill pads to be seen near the path along the creek. According to the Iceland Geosurvey (ISOR) one of the "boreholes started erupting intermittently in the winter of 2010". They reported that an interval of a few days between the eruptions. We found the spot but on two different visits to the field I saw no sign of geyser activity. ISOR also reports "another old borehole blew up in 1999 forming a crater with a diameter of about 30 m, now filled by mud except where a flow of steam keeps boiling pits open". That unexpected explosion in 1999 reportedly caused the geothermal project to be halted. The springs have been preserved due to the lack of drilling and geothermal exploitation.
Temperatures are over 200 degrees C just below the surface. Geologist from the Iceland Geosurvey believe "the water of the pools is surface water heated by steam from a boiling geothermal reservoir. Accompanying gases such as hydrogen sulphide and carbon dioxide acidify the water and alter the rock to clay. Only the uppermost 300 m of the reservoir at Seltún is boiling, i.e., follows the boiling curve in accordance with increasing pressure. Below this depth, a temperature inversion occurs, indicating that the boiling section is fed laterally from an upflow some distance away.”
The geothermal field is located in the Reykjanes Geopark.
Geologic and geothermal info from Iceland GeoSurvey (ISOR) . Some text in the caption from their web page at: www.geothermal.is/17-seltun-high-temperature-area-solfataras