Strike-slip faulting during the 2014 Bároarbunga-Holuhraun dike intrusion, central Iceland

• Main Authors: Ágústsdóttir, T, Woods, J, Greenfield, T, Green, RG, White, RS, Winder, T, Brandsdóttir, B, Steinthórsson, S, Soosalu, H
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2016
• Subjects: dike propagation; dike tip fracture; earthquake mechanisms; rifting; Bárðarbunga; Holuhraun; Woodcock; Iceland
• Online Access: https://www.repository.cam.ac.uk/handle/1810/254900

<jats:title>Abstract</jats:title><jats:p>Over a 13 day period magma propagated laterally from the subglacial Bárðarbunga volcano in the northern rift zone, Iceland. It created > 30,000 earthquakes at 5–7 km depth along a 48 km path before erupting on 29 August 2014. The seismicity, which tracked the dike propagation, advanced in short bursts at 0.3–4.7 km/h separated by pauses of up to 81 h. During each surge forward, seismicity behind the dike tip dropped. Moment tensor solutions from the leading edge show exclusively left‐lateral strike‐slip faulting subparallel to the advancing dike tip, releasing accumulated strain deficit in the brittle layer of the rift zone. Behind the leading edge, both left‐ and right‐lateral strike‐slip earthquakes are observed. The lack of non‐double‐couple earthquakes implies that the dike opening was aseismic.</jats:p> Seismometers were borrowed from the Natural Environment Research Council (NERC) SEIS-UK (loans 968 and 1022),with funding by research grants from the NERC and the European Community’s Seventh Framework Programme grant 308377 (Project FUTUREVOLC), and graduate studentships from the NERC and Shell. We thank Ágúst Þór Gunnlaugsson and others who assisted with fieldwork in Iceland and Nigel Woodcock for his helpful discussions. M.T. Gudmundsson, H. Reynolds, and Þ. Högnadóttir supplied ice cauldron coordinates. The Icelandic Meteorological Office, Chris Bean (University College Dublin), and the British Geological Survey kindly provided additional data from seismometers in northeast Iceland, data delivery from IMO seismic database 20151001/01. We thank the two anonymous reviewers for their constructive comments. Hypocenter locations in Figure 1 are listed in Tables S2 and S3. (Department of Earth Sciences, Cambridge contribution ESC3539). This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/2015GL067423