Rit (Vísindafélag Íslendinga) - 01.06.1971, Page 74

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GUÐMUNDUR PÁLMASON
about 0.2 km. The delay time of the P3-wave is relatively great, but
from the two seismometer stations, at which the P3-wave was ob-
served as a first arrival, it appears to be decreasing rapidly in the di-
rection of the profile to the westnorthwest. The most likely value of
the delay time in the eastem part of the Breiddalur valley is about
0.47 sec. This gives an estimated depth to layer 3 of 3.5 km. The delay
times on this profile indicate that this depth is sharply decreasing to
the westnorthwest as it should do by comparison with the Skriddal-
ur profiles.
The Lón profile (28) runs from a shot point near Hvalnes in a
west to southwest direction. Layer 2 is here found at the surface. The
delay time of the P3-wave appears to be about 0.15 sec, increasing to
about 0.25 sec near the southwestern end of the profile. The inferred
depths to layer 3 are about 1.2 km near Hvalnes, increasing to about
2.0 km at a distance of 15—20 km to the southwest.
In Homafjördur the Stokksnes-Hoffell profile (29) indicates a
fairly constant delay time of the P3-wave of about 0.23 sec. Layer 2
is also here at the surface and this gives therefore a depth of about
1.8 km to layer 3.
The Mýrar-Sudursveit profile (30) runs from a shot point near
Vidbordsfjall to the southwest. Near the shot point layer 2 is at the
surface. The delay time of the P3-wave increases considerably to the
southwest, which could be due to an increased thickness of layer 2, or
to the existence of an increasing thickness of layer 1, or perhaps to
both. The most probable cause is an increased thickness of layer 1. A
delay time of about 0.25 sec is indicated at the shot point, increasing
to about 0.45 sec near the end of the profile. The depth to layer 3 at
the shot point is about 2.0 km. If the increase in delay time along the
profile is assumed to be due to the existence of layer 1, the inferred
depth to layer 3 near the end of the profile is about 3.1 km.
6.10. Offshore profiles.
A total of eight profiles were measured off the west and south
coasts in the summers of 1966 and 1967. The location of six of them
is shown in Fig. 2. The seventh, Kjalames-Faxaflói (48), is shown
in Fig. 1. The eighth one was measured from the south coast in Land-
eyjar in a SSW direction across the Vestmann Islands. The arrivals
on this profile were very poor and it has therefore not been used for