Extension deficit builds up over centuries at divergent plate boundaries and is recurrently removed during rifting events, accompanied by magma intrusions and transient metre-scale deformation. However, information on transient near-field deformation has rarely been captured, hindering progress in understanding rifting mechanisms and evolution. Here we show new evidence of oblique rift opening during a rifting event influenced by pre-existing fractures and two centuries of extension deficit accumulation. This event originated from the Bárðarbunga caldera and led to the largest basaltic eruption in Iceland in >200 years. The results show that the opening was initially accompanied by left-lateral shear that ceased with increasing opening. Our results imply that pre-existing fractures play a key role in controlling oblique rift opening at divergent plate boundaries.
Oblique rift opening revealed by reoccurring magma injection in central Iceland 2016, 7:12352 Nature Communications
We thank Sturla Thengilsson, Jon Harrington and Daniele Trippanera for help with fieldwork. We also thank Eleonora Rivalta (GFZ Potsdam) for constructive discussions, Michelle Parks and Freysteinn Sigmundsson (University of Iceland) for the help with accessing the SAR data and Kristín Vogfjörð (Icelandic Meteorological Office) for providing the relocated seismic data from ref. 7. Finally, we thank Cindy Ebinger and two anonymous reviewers for their comments. The COSMO-SkyMed data were provided by the Italian Space Agency (ASI) and the TerraSAR-X data by the German Space Agency (DLR) through the Icelandic Volcanoes Supersite project supported by the Committee on Earth Observing Satellites (CEOS). The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST).