Micrometre-scale deformation observations reveal fundamental controls on geological rifting

Thun, Johannes and Lokmer, Ivan and Bean, Christopher J. and Eibl, Eva P. S. and Bergsson, Bergur H. and Braiden, Aoife (2016) Micrometre-scale deformation observations reveal fundamental controls on geological rifting. Scientific Reports, 6.

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Thun_Lokmer_Bean_Eibl_Bergsson_Braiden_2016_Micrometer-scale deformation observations reveal fundamental controls on geological rifting.pdf

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Abstract

Many of the world’s largest volcanic eruptions are associated with geological rifting where major fractures open at the Earth’s surface, yet fundamental controls on the near-surface response to the rifting process are lacking. New high resolution observations gleaned from seismometer data during the 2014 Bárðarbunga basaltic dyke intrusion in Iceland allow us unprecedented access to the associated graben formation process on both sub-second and micrometre scales. We find that what appears as quasi steady-state near-surface rifting on lower resolution GPS observation comprises discrete staccatolike deformation steps as the upper crust unzips through repetitive low magnitude (MW < 0) failures on fracture patches estimated between 300 m2 and 1200 m2 in size. Stress drops for these events are one to two orders of magnitude smaller than expected for tectonic earthquakes, demonstrating that the uppermost crust in the rift zone is exceptionally weak.

Item Type: Article
Divisions: School of Cosmics Physics
School of Cosmics Physics > Geophysics
Date Deposited: 05 Apr 2018 13:27
Last Modified: 05 Apr 2018 13:27
URI: http://dair.dias.ie/id/eprint/383

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