Rit (Vísindafélag Íslendinga) - 01.06.1967, Qupperneq 143
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DISCUSSION
S. Thorarinsson: The eruption fissures that have opened
up during the Surtsey eruption seem to be arranged en eche-
lon. In the area between Mývatn and Jökulsá á Fjöllum
some fissures seem to run parallel for miles without echelon
arrangement. This should, however, be studied more closely
on aerial photos.
Th. Sigurgeirsson: Is the angle between the stepped frac-
tures and the principal fracture dependent on material pro-
perties?
Trausti Einarsson: For shearing cracks the deviation from
the direction of the main shearing movement is little depen-
dent on the material. Tensile cracks in soil are different.
K. Saemundsson: I want to remind of the well known ex-
periments carried out by Prof. H. Cloos on updoming and
also stretching of a clay-cake. The fault pattern obtained in
this way — in both cases the result of forces pulling apart —
is extremely similar to what we see in our Icelandic active
fault zones today. Prof. T. Einarsson has put emphasis on
local structures believed by him not to harmonize with nor-