On the Origin of Seismic Anisotropy in the Shallow Crust of the Northern Volcanic Zone, Iceland ...

• Main Authors: Bacon, CA, Johnson, JH, White, RS, Rawlinson, N
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2022
• Subjects: seismic anisotropy; Askja; Iceland; shear-wave splitting; stress modeling; Mid-Atlantic Ridge
• Online Access: https://dx.doi.org/10.17863/cam.80606; https://www.repository.cam.ac.uk/handle/1810/333183

AbstractThe Icelandic crust is a product of its unique tectonic setting, where the interaction of an ascending mantle plume and the Mid‐Atlantic Ridge has caused elevated mantle melting, with the melt accreted and cooled in the crust to form an oceanic plateau. We investigate the strength and orientation of seismic anisotropy in the upper crust of the Northern Volcanic Zone using local earthquake shear‐wave splitting, with a view to understanding how the contemporary stress field may influence sub‐wavelength structure and processes. This is achieved using a data set comprising 50,000 earthquakes located in the top 10 km of the crust, recorded by up to 70 stations over a 9 year period. We find that anisotropy is largely confined to the top 3–4 km of the crust, with an average delay time of 0.10 ± 0.05 s, and an average orientation of the fast axis of anisotropy of N014°E ± 27°, which is perpendicular to the spreading direction of the Eurasian and North American plates (N106°E). These results are consistent ...