Rit (Vísindafélag Íslendinga) - 01.06.1971, Qupperneq 73

CRUSTAL STRUCTURE OF ICELAND
73
Fig. 26. Toíal delay time of the Pa-wave, E-Iceland.
stadir to Skriduvatn. The apparent P3-wave velocities are somewhat
lower than 6.5 km/sec for hoth profile directions. The delay time of
the P3-wave can he computed by eqn. (4.1.4) at distances between
10 and 25 km from the shot point at Egilsstadir. It is found to have a
minimum value of about 0.24 sec at a distance of 20—25 km, near
Thingmúli. The delay times at the shot points are equal, since the
travel times midway between the shot points are equal on both pro-
files (i.e. 8TSl s2 =0).
If the P3-wave velocity is assumed to be 6.5 km/sec, a value of
0.36 sec is obtained for the shot point delay times. This is in fairly
good agreement with what would be expected from the neighbouring
profiles 25 and 27. A lower value of the P3-wave velocity would give
lower shot point delay times, which is less in agreement with what
would be expected.
The inferred shallowest depth to layer 3 under the profile is about
1.6 km, or 1.5 km below sea level. At the shot point at Egilsstadir the
inferred depth to layer 3 is about 2.7 km below sea level, and at the
shot point in Skriduvatn it is about 2.4 km.
The Breiddalur profile (27) shows a somewhat different structure
in that layer 2 appears to be close to the surface, perhaps at a depth of