Rit (Vísindafélag Íslendinga) - 01.06.1971, Síða 25

CRUSTAL STRUCTURE OF ICELAND
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Fro. 5. Histogram of apparent P-wave velocities on refraction profiles in Iceland.
to the much smaller number of profiles of sufficient length to show
the P4-wave, as compared with the number of shorter profiles show-
lng layers up to and including layer 3. The existence of layer 4 is
as well estahlished as the existence of the other layers.
5.2. P-wave velocities.
Average values of apparent P-wave velocities have been computed
from the data in Fig. 5 and are given below. The error limits are the
standard deviation of the mean value, assuming the layers to be the
same everywhere. The standard deviation s of a single determination
is also given, as well as the number of values used in calculating each
mean value.
Table 5.3.
Layer P-velocity km/sec s km/sec n
0 2.75 ± 0.06 0.37 35
1 4.14 ± 0.03 0.24 63
2 5.08 ± 0.03 0.24 59
3 6.35 ± 0.03 0.21 72
No attempt has heen made to calculate in a similar way the
P-wave velocity in layer 4, since the aeterminations are too few and
too much affected by dips in the 3-4 boundary. The most prohable
value of this velocity is discussed in detail in sect. 5.5, as well as the
reasons for choosing a value of the P3-wave velocity different from