@article{fdi:010058943,
  title = {{I}mplications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east {I}celand rift zone},
  author = {{P}lateaux, {R}. and {B}ergerat, {F}. and {B}ethoux, {N}. and {V}illemin, {T}. and {G}erbault, {M}uriel},
  editor = {},
  language = {{ENG}},
  abstract = {{C}omparison of the eroded off-rift zone left inactive by plate motion with the inner active seismic rift zone allows us to constrain the fracturing mechanisms. {I}n eastern off-rift zone, we measured 423 fault slips (including normal and strike-slip faults). {I}nversion of fault slip data reveals the parallelism of the minimum stress (sigma(3)) computed for the normal and for the strike-slip faulting, and consistency with the direction of plate divergence. {N}orth of the {V}atnajokull, in the active rift zone, we analysed 14,250 earthquakes recorded by the {I}celandic {M}eteorological {O}ffice ({IMO}) between 2004 and 2009, especially northeast of the {A}skja volcano. {T}wo main average focal depths were determined at 5 km ({H}eroubreio table mountain) and 15 km ({U}pptyppingar hyaloclastite ridge). {T}he double couple focal mechanisms determined by {IMO} revealed that more than half of the mechanisms are strike-slip. {F}aulting type both in active and off-rift zone reveals an unusual importance of strike-slip regime in such an extensional tectonic context. {T}his can be explained by stress permutations (sigma(1)/sigma(2)). {S}imilarities in terms of stress orientations and type of faulting are observed both in the old and present-day rift zones. {W}e assume that the seismic events may be generated by rapid deep magma intrusion, also associated with shallower hydrothermal activities. {W}e thus propose that the presence of fluids, shear failure (double couple focal mechanism) and stress permutations in both active and off-rift zones are closely linked. {A}ssuming a {D}rucker-{P}rager failure criterion, we evaluated analytically that a state near of lithostatic pore pressure is a necessary condition for shear failure at shallow (5 km) and deep (15 km) depth, in a simple context of crustal extension that allows for stress permutations. {H}owever, processes favouring stress permutations cannot be further constrained from our observations since the dynamics of fluid, materiel heterogeneity and post-glacial rebound can also play a significant role.},
  keywords = {{I}celandic rift ; {S}tress permutation ; {V}olcano-tectonics ; {P}aleostresses ; {F}luid pore pressure ; {F}racturing mechanisms ; {ISLANDE}},
  booktitle = {},
  journal = {{T}ectonophysics},
  volume = {581},
  numero = {{SI}},
  pages = {19--34},
  ISSN = {0040-1951},
  year = {2012},
  DOI = {10.1016/j.tecto.2012.01.013},
  URL = {https://www.documentation.ird.fr/hor/fdi:010058943},
}