temperature and pressure in the svartsengi ... - Orkustofnun

1 72.3 Resistivity studies of the fieldSurface hydrothermal manifestations are meager within theSvartsengi field and only scattered over about 4 squarekl1ometers. The resistivity surveys (Fig. 4) show thegeothermal area to be elongated NE - SW 1n the northern partbut ESE-WSW in the southern part (Georgsson, 1981), Acontinuous E- W striking low resistivity zone whichcoincides fairly closely wi th the Reykjanes seismic zonetha t has been interpreted as a plate boundary. Study ofcorrelation between resistivity salinity and temperatureseem to confirm that the low resistivity can only beexplained by anomalously high heat flow . This indicatesthat explol table geothermal energy may be found 1n theuppermost 1 - 2 km along the plate boundaries on theReykjanes Peninsula even far away from surface manifestations.2.~ TectoniC activity of the Reykjanes peninsulaOne can see the main zone of earthquakes and location ofquake epicenters on the area from Fig. 1. The tectonicactivity increases the permeability and thus creates somesort of a drainage system along the zone of earthquakes.Some geothermal areas like Svartsengi are situated wheresurface fissure swarms intersect the main zone of earthquakes.2.5 Hydrological characteristics of the geotherma l systemThe water percolates down from the infiltration area andflows along the permeable earthquake zone. On its way itwarms up and mixes with intrusive seawater. Where thesurface fissure swarms intersect the earthquake zone. thepermeability becomes great enough to allow free convection,thus forming a geothermal area.