Greinar (Vísindafélag Íslendinga) - 01.01.1976, Side 64

62
Changes
North of Hekla
m
10
ro
(O
ro
ro
Fig. 1: Appareiit changes in the length of geodimeter survey lines north of Hekla
Volcano from 1967 to 1973. The vertical scale is mm of change and the horizontal
scale is the length of segments of the survey profile in km. Apparent strain is the
aspect ratio of the hars.
either redistribution of any real tectonic strain that may have oc-
curred during 1967-1970, or as erratic movement of the bench
marks in that area. The eastern rift zone shows no net extension
or contraction for the entire period 1967-1973 (Figure 2,3).
In the westem rift zone the 1973 data show that an apparent
net extension of at least 4 cm occurred during the period 1967-
1973 (Figures 4,5) including 2 cm of extension of the well-con-
trolled survey lines across the north end of Lake Thingvellir (the
lines which showed no change in 1967-1970, Figure 6). Points