end, the meltwater lakes drained and at least one of the eruption centers produced subaerial lava, which means that there is a tuya component in the ridge, not all of it was produced by subglacial eruptions. The eruption in the whole was probably similar to the Gjálp eruption within the Grímsvötn Volcanic System in 1996. Geothermal activity at Sveifluháls Especially in two areas, geothermal activity at Sveifluháls is intense and connected to Krysuvík volcanic system. These are Seltún on the one hand, and the hills behind the farm and school of Krýsuvík on the other hand (so called Hveradalir ). Hot ground, fumaroles, hot springs and mud pots are to be found there. Measurements in Seltún even show a thermal output of about 4 MW. Hydrothermal alteration and this heat lead to precipitation of minerals like hematite, goethite and different sulfur compounds. Hiking Many hiking trails lead up on Sveifluháls or are to be found in the vicinity. For example, there are trails up from Seltún at the southern end of the ridge to Arnarvatn and from there into the Móhálsadalur , or for hiking a round to Hetta , one of the southernmost summits of the long Sveifluháls ridge. There is also the possibility to hike from Vatnsskarð (Reykjanes) up on Sveifluháls and follow the ridge to the highest summit Stapatindur . See also Krýsuvík (volcanic system) Geology of Reykjanes Peninsula Subglacial volcano External links General information http://icelandicvolcanos.is/?volcano=KRI Krýsuvík. Catalogue of Icelandic Volcanoes. https://volcano.si.edu/volcano.cfm?vn=371030 Krýsuvík. Global Volcanism Program. Smithsonian Institution. Volcano monitoring Icelandic Met Office (IMO). Earthquake Monitoring. Reykjanes Peninsula IMO. Aviation Color Code Tourism Sveifluháls. Visit Reykjanes. Official Website. Further reading Holly M. Kagy: Interaction of Basaltic Dikes and Wet Lapilli Tuff at Glaciovolcanic Centers: A Case Study of Sveifluháls, Iceland as a Terrestrial Analog for Dike-Cryosphere Interaction on Mars. University of Pittsburgh. (2011) References Subglacial volcanoes of Iceland Reykjanes Krýsuvík Volcanic System Reykjanes Volcanic Belt Mountains of Iceland Hyaloclastite ridges