Geothermal Exploration in Graendalur Valley, Hveragerdi, S-Iceland

Abstract

ABSTRACT Geothermal mapping was conducted in Graendalur valley, which is located north of Hveragerdi town, South Iceland. The area is at the eastern margin of the Western Volcanic Zone (WVZ) and the South Iceland Seismic Zone (SISZ). The geothermal manifestations are related to the SISZ and the older part of Hengill central volcano (Hveragerdi volcanic system). The scope of this study was to map all superficial geothermal manifestations and alterations in order to examine the relationship between them and the structures. Then the results were compared with previous works in 1995 and 2009 to know whether changes occurred after the earthquakes in 2008. During the survey more than 217 geothermal manifestations were recognized and mapped. These are fumaroles/steam vents, mud pools, warm to hot springs, warm to steaming grounds and mineral precipitations. The results show the presence of thermal fluid circulation near the surface. Thermal fluid movement is governed by subsurface structures trending NE- SW, N-S and NW-SE. The 2008 earthquake produced some new geothermal manifestations and increased the activity of the already existing in that time. In the Graendalur valley new geothermal activities are still occurring.