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Eight centuries of volcanism at the center of Icland hotspot reveald by glacier tephrostratigraphy
Guðrún Larsen
Magnús T. Guðmundsson
Helgi Björnsson
Sience Institute, University of Iceland, Dunhagi 3, IS-107 Reykjavík, Iceland
A record of volcanic activity within the Vatnajökull ice cap has been obtained by combining data from three
sources: tephrostratigraphic studies of two outlet glaciers, a 415-m-long ice core from northwestern Vatnajökull,
and written records. The record extends back to A.D. 1200 and shows that the volcanic activity has a 130-140 yr.
period. Intervals of frequent eruptions with recurrence times of three to seven years alternate with intervals of
similar duration having much lower eruption frequency. In comparison with other parts of the plate boundary in
Iceland, eruption frequency is grater, episodes of unrest are longer, and intervals of low activity are shorter.
The high eruption frequency may be the result of a more sustained supply of magma, owing to the area´s location
above the center of the Icland mantel plume. When combined with historical data on eruptions and earthquakes, our
data indicate that rifting-related activity in Iceland as a whole is periodic and broadly in phase with the volcanic
activity within Vatnajökull