@article{ZieglerRajabiHeidbachetal.2016,
  author    = {Ziegler, Moritz O. and Rajabi, Mojtaba and Heidbach, Oliver and Hersir, Gylfi Pall and Agustsson, Kristjan and Arnadottir, Sigurveig and Zang, Arno},
  title     = {The stress pattern of Iceland},
  series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth},
  volume    = {674},
  journal   = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0040-1951},
  doi       = {10.1016/j.tecto.2016.02.008},
  pages     = {101 -- 113},
  year      = {2016},
  abstract  = {Iceland is located on the Mid-Atlantic Ridge which is the plate boundary between the Eurasian and the North American plates. It is one of the few places on earth where an active spreading centre is located onshore but the stress pattern has not been extensively investigated so far. In this paper we present a comprehensive compilation of the orientation of maximum horizontal stress (S-Hmax). In particular we interpret borehole breakouts and drilling induced fractures from borehole image logs in 57 geothermal wells onshore Iceland. The borehole results are combined with other stress indicators including earthquake focal mechanism solutions, geological information and overcoring measurements resulting in a dataset with 495 data records for the S-Hmax orientation. The reliability of each indicator is assessed according to the quality criteria of the World Stress Map project The majority of S-Hmax orientation data records in Iceland is derived from earthquake focal mechanism solutions (35\%) and geological fault slip inversions (26\%). 20\% of the data are borehole related stress indicators. In addition minor shares of S-Hmax orientations are compiled, amongst others, from focal mechanism inversions and the alignment of fissure eruptions. The results show that the S-Hmax orientations derived from different depths and stress indicators are consistent with each other. The resulting pattern of the present-day stress in Iceland has four distinct subsets of S-Hmax orientations. The S-Hmax orientation is parallel to the rift axes in the vicinity of the active spreading regions. It changes from NE-SW in the South to approximately N-S in central Iceland and NNW-SSE in the North. In the Westfjords which is located far away from the ridge the regional S-Hmax rotates and is parallel to the plate motion. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{ReiterHeidbachSchmittetal.2014,
  author    = {Reiter, Karsten and Heidbach, Oliver and Schmitt, Douglas and Haug, Kristine and Ziegler, Moritz O. and Moeck, Inga},
  title     = {A revised crustal stress orientation database for Canada},
  series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth},
  volume    = {636},
  journal   = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0040-1951},
  doi       = {10.1016/j.tecto.2014.08.006},
  pages     = {111 -- 124},
  year      = {2014},
  abstract  = {The Canadian database on contemporary crustal stress has not been revised systematically in the past two decades. Here we present the results of our new compilation that contains 514 new data records for the orientation data of maximum compressive horizontal stress and 188 data records that were re-assessed. In total the Canadian stress database has now 1667 data records, which is an increase of about 45\%. From these data, a new Canadian Stress map as well as one for the Province of Alberta is presented. To analyse the stress pattern, we use the quasi median on the circle as a smoothing algorithm that generates a smoothed stress map of the maximum compressive horizontal stress orientation on a regular grid. The newly introduced quasi interquartile range on the circle estimates the spreading of the data and is used as a measure for the wave-length of the stress pattern. The result of the hybrid wavelength analysis confirms that long spatial wavelength stress patterns (>= 1000 km) exist in large areas in Canada. The observed stress pattern is transmitted through the intra-plate regions. The results reveal that shorter spatial wave length variation of the maximum compressive horizontal stress orientation of less than 200 km, prevails particularly in south-eastern and western Canada. Regional stress sources such as density contrasts, active fault systems, crustal structures, etc. might have a significant impact in these regions. In contrast to these variations, the observed stress pattern in the Alberta Basin is very homogeneous and mainly controlled by plate boundary forces and body forces. The influence of curvature of the Rocky Mountains salient in southern Alberta is minimal. The present-day horizontal stress orientations determined herein have important implications for the production of hydrocarbons and geothermal energy in the Alberta Basin. (C) 2014 Elsevier B.V. All rights reserved.},
  language  = {en}
}