Main Article Content
Prior to the present activity of the Krafla volcano, which started in 1975, levelling and gravity surveys had been carried out in the area. The network has since been extended, and measurements are carried out about every second month. The measurements reveal a quasi-periodic behaviour of the tectonic activity, characterized by slow inflation of the caldera for several weeks or months at a rate of 6–10 mm/d, interrupted by sudden subsidence events lasting for one or a few days. Elevation changes within the caldera are described by a deflation-inflation swelling with its apex near the center of the caldera. Calculations. using a model of a spherical chamber with varying pressure at 3 km depth, show good agreement with the measured elevation values. Comparison of gravity and levelling data, using a Bouguer type relationship, suggests that inflation and deflation of the floor of the caldera is caused entirely by in- and outflow of magma. Some discrepancies between the levelling and gravity data immediately after subsidence events can be explained by additional mass flow of groundwater.
Authors who publish with this journal as of Vol. 63 agree to the following terms:
a. Authors share the copyright with this journal in equal parts (50% to the journal, 50% to the lead author), and grant the journal right of first publication, with the work after publication simultaneously licensed under Creative Commons Attribution License CC BY-NC-ND 4.0 that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
b. Authors may enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal, and a reference to this copyright notice.
c. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) during the submission process, as this can lead to productive exchanges and earlier and greater citation of published work and better sales of the copyright.
Authors retain copyright and grant the Journal of Geophysics right of first publication, with the work three years after publication simultaneously licensed under the Creative Commons BY-NC-ND 4.0 License that allows others to share the work (with an acknowledgment of the work's authorship and initial publication in this journal), except for commercial purposes and for creating derivatives.
Authors can enter into separate, additional, but non-commercial contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository, but not publish it in a book), with an acknowledgment of its initial publication in this journal.
Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) before and during the submission process, as that can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
This journal is one of a handful of scholarly journals that publish original scientific works under CC BY-NC-ND 4.0 - the only Creative Commons license affording the authors' intellectual property absolute worldwide protection.
Journal of Geophysics is published under the scholar-publishers model, meaning authors do not surrender their copyright to us. Instead, and unlike corporate publishers like Elsevier or Springer Nature that resell copyright to third-parties for up to $80,000 (per paper, per transaction!), the Journal of Geophysics authors share copyright equally with this journal.
Therefore, all the proceeds from reselling copyright to third parties get shared to equal parts (50% to the journal, 50% to the lead author). Under the Berne Convention, this protection is an inheritable right that lasts for as long as the rightsholder lives + 50 years.
By submitting to this journal, the lead author, on behalf of all co-authors, grants permission to this journal to represent all co-authors in negotiating copyright sales and collecting proceeds. The lead author should negotiate with his/her co-authors the modalities of distributing the lead author's portion of the proceeds. Usually, this is per pre-agreed percentage of each co-author's contribution to creating the copyrighted work. (more...)
Bjornsson, A., Johnsen, G.V., Sigurdsson, S., Thorbergsson, G., Tryggvason, E. (1979) Rifting of the plate boundary in North Iceland 1975-1978. J. Geophys. Res. 84 (In press)
Bjornsson, A., Saemundsson, K., Einarsson, P., Tryggvason, E., Gronvald, K. (1977) Current rifting episode in North Iceland. Nature 266:318-323
Brandsdottir, B., Einarsson, P. (1979) Seismic activity associated with the September 1977 deflation of the Krafla central volcano in NE-Iceland. J. Volc. Geotherm. Res. (In press)
Einarsson, P. (1978) S-wave shadows in the Krafla caldera in NE-Iceland, evidence for a magma chamber in the crust. Bull. Volcanol. 41:1-9
Gerke, K. (1974) Crustal movements in the Myvatn- and the Thingvallavatn-area, both horizontal and vertical. In: Kristjansson, L. (Ed.) Geodynamics of Iceland and the North Atlantic area, pp. 263-275. D. Reidel Publishing Company, Dordrecht, Boston
Gerke, K. (1977) Uber neuere horizontale und vertikale Krustenbewegung in Island. Mitteilungen der Technischen Universitat Carolo-Wilhelmina zu Braunschweig XII, Heft III/IV
Gerke, K., Moller, D., Ritter, B. (1978) Geodatische Lagemessungen zur Bestimmung horizontaler Krustenbewegungen in NordostIsland. In: Festschrift fur W. Hopcke, Wiss. Arb. d. Lehrst. f. Geodasie, Photogramm. u. Kartogr. an d. T.U. Hannover, Nr. 83, Hannover
Hunt, T.M. (1976) Recharge of water in Wairakei geothermal Field determined from repeated gravity measurements. N. Z. J. Geol. Geophys. 20:307-317
Ito, K., Kennedy, G.C. (1971) An experimental study of the basaltgarnet granulite-eclogite transition. In: Heacock, J.G. (Ed.) The structure and physical properties of the Earth's crust, Vol. 14:303-314. Washington, D.C. Geophys Monogr. Am. Geophys. Union
Longman, J.M. (1959) Formulas for Computing the tidal accelerations dueto the Moon and the Sun. J. Geophys. Res. 64:2351-2355
Moller, D., Ritter, B. (1980) Geodetic measurements and horizontal crustal movements in the rift zone of NE-Iceland. J. Geophys. 47:110-119
Mogi, K. (1958) Relations between the eruptions of various volcanoes and the deformation of the ground surfaces around them. Bull. Earthq. Res. Inst. 36:99-134
Niemczyk, O. (1943) Spalten auf Island. Wittwer, Stuttgart
Palma son, G. (1971) Crustal structure of Iceland from explosion seismology. Soc. Sci. Islandica, Rit XL
Palmason, G., Nilsen, T.H., Thorbergsson, G. (1973) Gravity base station network in Iceland 1968-1970. JOkull 23:70-125
Saemundsson, K. (1974) Evolution of the axial rifting zone in Northern Iceland and the Tjornes Fracture Zone. Geol. Soc. Am. Bull. 85:495-504
Saemundsson, K. (1978) Fissure swarms and central volcanoes of the neovolcanic zones of Iceland. In. Crustal evolution in Northwest Britain and adjacent regions. Geol. J. Spec. Issue 10:415-432
Schleusener, A., Torge, W. (1971) Investigations of secular gravity variations in Iceland. J. Geophys. 37:679-701
Schleusener, A., Torge, W., Drewes, H. (1976) The gravity field of Northeastern Iceland. J. Geophys. 42:27-45
Sigurdsson, O. (1976) Natturuhamfarir i Thingeyjarthingi (In Icelandic with English summary). Tyli 6:3-20
Spickernagel, H. (1966) Hohenmessungen in Nord-Island. Mitt. Markscheidewesen 73:139-152
Torge, W., Drewes, H. (1977a) Gravity variations with time in Northern Iceland 1965-1975. J. Geophys. 43:771-790
Torge, W., Drewes, H. (1977b) Gravity changes in connection with the volcanic and earthquake activity in Northern Iceland 1975/1976. Jokull 27:60-69
Torge, W., Kanngieser, E. (1980) Gravity and height variations during the present rifting episode in northern Iceland. J. Geophys. 47:125-131