Jökull - 01.12.1977, Blaðsíða 71

recent volcanism at Leirhnjúkur antl following
earthquake activity are of local character. Gravi-
ty changes generally reach the order of 0.1 mgai,
only near Krafla changes of a few tenths of
mgal have been found. Tlie gravity increase at
Námaskard shows a significant correlation with
lreight decrease.
ACKNOWLEDGEMENTS
The anthors thank the National Research
Council of Iceland for the permission to carry
out the gravity sarvey in Iceland. For valuable
assistance and fruitful discussions they are grate-
ful to Dr. Gudmundur Pálmason, Reykjavik.
Sincere thanks are due to the Geodetic Insti-
tute, Technical University Berlin (Profs. Dr.-
Ing. S. Heitz, Dr.-Ing. K. Marzahn) for lending
the LCR-gravity meter no. 85. Calculations have
been carried out with the CDC 73/76 of the
Regional Computing Centre of Lower Saxony.
The authors are very grateful to the German
Research Society (Deutsche Forschungsgemein-
schaft), which generously sponsored the invest-
igations.
REFERENCES
Barnes, D. F. 1966: Gravity changes during the
Alaska earthquake. T. Geophys. Res. 71,
451-456.
Fujita, N., Y. Fujii. 1973: Gravity change in
Japan. In: R. S. Mather, P. V. Angus-Lep-
pan (eds.), Proc. of Symp. on Earth’s Gravi-
tational Field and Secular Variations in
Position, Sydney, Australia, 218—221.
Gerke, K. 1974: Crustal movements in the Mý-
vatn- and in the Thingvallavatn-area, both
horizontal and vertical. In: L. Kristjánsson
(ed.), Geodynamics of Iceland and the North
Atlantic Area. D. Reidel Publ. Co., Dord-
recht, 263-275.
Morelli, C., C. Gantar, T. Honkasalo, R. K.
McConnel, B. Szabo, J. Y. Tanner, U. Uo-
tila, C. T. Whalen. 1974: The International
Gravity Standardization Net 1971 (IGSN
71). Assoc. Intern. de Géodésie, Publ. Spec.
No. 4, Paris.
Niemczyk, O., E. Emschermann. 1943: Sonder-
dreiecksmessung auf Island zur Feststellung
feinster Erdkrustenbewegungen. In: In:
O. Niemczyk (ed.), Spalten auf Island, K.
Wittwer, Stuttgart, 80—113.
Pálmason, G. 1971: Crustal structure of Ice-
land from explosion seismology. Vísindafé-
lag íslendinga (Soc. Scient. Islandica) XL,
Leiftur, Reykjavík.
Schleusener, A. 1943: Die Gravimetermessung-
en. In: O. Niemczyk (ed.), Spalten auf Is-
land, K. Wittwer, Stuttgart, 124—175.
Schleusener, A., W. Torge. 1971: Investigations
of secular gravity variations in Iceland. Z.
f. Geophysik 37, 679-701.
Schleusener, A., W. Torge, H. Drewes. 1974:
Prázisionsschweremessungen in Nordostis-
land 1970/71. Deutsche Geod. Komm., B
206, Múnchen.
Schleusener, A., W. Torge, H. Drewes. 1976:
The gravity field of northeastern Iceland.
J. of Geophysics 42, 27—45.
Spickernagel, H. 1966: Höhenmessungen in
Nord-Island. Mitt. aus dem Markscheide-
wesen 73, 139—152.
Spickernagel, H. 1968: Erdkrustenbewegungen
in Island. Umschau 68, 379.
Strange, W. D. G. Carroll. 1976: Repeated
gravity measurements prior to the San Fern-
ando earthquake (abstract). EOS, Trans.
Am. Geophys. Union 57, 288.
Torge, W., H. Drewes. 1977: Gravity variations
with time in northern Iceland 1965—1975.
J. of Geophysics 43, 771—790.
Torge, W., H.-G. Wenzel. 1976: Gravimetric
earth tide observations in Iceland. Bull.
d’Inform. Marées Terrestres, Bruxelles, 74,
4312-4318.
Tryggvason, E. 1974: Vertical crustal movement
in Iceland. In: L. Kristjánsson (ecl.), Geo-
dynamics of Icelaml and the North At-
lantic Area, D. Reidel Publ. Co., Dordrecht,
241-262.
JÖKULL 27. ÁR 69