Jökull - 01.12.1961, Page 46

a base temperature below 90 or 100 °C. The pre-
sence of these gases can therefore be regardecl
as an evidence for a base temperature above
100 °C. However, the experimental data are
still too few in order to warrant definite conclu-
sions.
5. RESULTS FROM THERMAL AREAS
This paragraph illustrates a few resuits which
have been obtained on the basis of thermal met-
hods in Icelancl. The observational data are
frorn three major thermal areas which are now
being exploited. One of the areas is located in
the city of Reykjavík, and the two other areas,
that is, the Reykir area ancl the Hengill area
are located 16 km north-east, respectively, 45 krn
east of the city. (See FIGURE I). The emphasis
is placed on temperature data which have been
of practical importance for exploration and ex-
ploitation.
(a) Reykjavík thermal area.
The presence of a thermal area in the city of
Reykjavík is indicated by two natural thermal
springs. The larger spring issuecl about 10 liters
per seconcl of water at 88 °C. Drilling for liot
water was initiated in 1928. Some moderate
results were obtained in the following two years
after the completion of 13 relatively shallow
boreholes. An additional borehole of 760 meters
was completed in 1944.
The exploration of the area was resumed in
1954. In view of the difficulties involved in the
application of electrical resistivity methods in a
populated area it was decided to carry out ther-
mal prospecting by means of a few shallow bore-
holes. A total of 12 boreholes, 30 to 80 meters
deep, was drillecl in the area. Temperature
measurements in these boreholes and clata from
the existing boreholes íurnishecl a relatively
good picture of the variation of the surface
temperature gradient in the area.
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