New constraints on dike injection and fault slip during the 1975–1984 Krafla rift crisis, NE Iceland

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Hollingsworth, J., Leprince, Sébastien, Ayoub, François, Avouac, Jean-Philippe
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2013
• Subjects: dike injection; Iceland; faulting; oceanic rifting; Krafla; optical image correlation; Renaud
• Online Access: https://doi.org/10.1002/jgrb.50223

Correlation of KH9 spy and SPOT5 satellite images, airphotos, digital elevation model differencing, electronic distance measurement, and leveling survey data is used to constrain the deformation resulting from the 1975–1984 Krafla rifting crisis. We find that diking typically extends to depths of 5 km, while the dike tops range from 0 km in the caldera region to 3 km at the northern end of the rift. Extension is accommodated by diking at depth and normal faulting in the shallowest crust. In the southern section of the Krafla rift, surface opening is 80% of the dike opening at depth. Over the 70–80 km length of the rift, the average dike opening was 4.3–5.4 m. From these estimates, we calculate the total geodetic moment released over the Krafla rift crisis, 4.4–9.0×10^(19) Nm, which is an order of magnitude higher than the seismic moment released over the same time period, ~5.8×10^(18) Nm. The total volume of magma added to the upper crust was 1.1–2.1×10^9m^3. This study highlights how optical image correlation using inexpensive declassified spy satellite and airphotos, combined with simple models of crustal deformation, can provide important constraints on the deformation resulting from past earthquake and volcanic events. © 2013 American Geophysical Union. Received 31 October 2012; revised 9 April 2013; accepted 19 May 2013; published 11 July 2013. Part of this research was funded by the Gordon and Betty Moore Foundation through Grant GBM 2808 to the Advanced Earth Observation Project at Caltech. We also thank the Keck Institute for Space Studies for financial support. Thora Arnadottir kindly provided EDM displacement data for the Krafla rift from 1978 to 1989 [Tryggvason, 1991]. Arzan Surazakov provided helpful advice and discussion regarding ortho-rectification of KH9 Hexagon data. The decision to look at displacement in the epipolar perpendicular direction was inspired by discussions with Renaud Binet. Bjarney Gudbjornsdottir and Carsten Kristinsson (National Land Survey of ...