Jökull - 01.01.2015, Side 43

Grain characteristics of tephra from Katla and Hekla eruptions
-4
-3
-2
-1
0
1
2
3
4
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
M
ea
n
g
ra
in
s
iz
e
(Ф
)
Dis tance from s ource (km)
Mean grain s ize of Hekla-1947 and S IL K -L N
plotted agains t dis tance from s ource
S IL K -L N
16
8
4
2
1
0.5
0.25
0.125
0.063
M
ea
n
g
ra
in
s
iz
e
(m
m
)Hekla-1947
Figure 14. Comparison of mean grain size along the thickness axes of the SILK-LN and Hekla 1947 tephra
plotted against distance from source. Circles represent Hekla 1947 and triangles represent SILK-LN. The mean
grain size of the SILK-LN at 22 km and Hekla 1947 at 68 km is similar, both for the bulk samples and individual
units. – Meðalkornastærð gjósku eftir þykktarásum SILK-LN og Heklu-1947 gjóskulaganna eftir fjarlægð frá
upptökum. Meðalkornastærð SILK-LN í 22 km fjarlægð og Heklu-1947 í 68 km frá upptökum er svipuð, bæði í
heildarsýnum og stökum einingum.
0
10
20
30
40
50
60
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
W
ei
g
h
t
%
Dis tance from s ource (km)
F ine proportions ≤4 Φ (≤0.063 mm) plotted agains t dis tance
S IL K -L N & Hekla-1947
S IL K -L N
Hekla-1947
Hekla-1947 (S Þ )
Figure 15. Comparison of the fine material in SILK-LN and Hekla-1947 tephras, all samples included. –
Þyngdarhlutföll fínefnis í SILK-LN og Heklu-1947 gjósku, öll mæld sýni.
JÖKULL No. 65, 2015 43