Game of zones. The quest for influence in Europe’s neighbourhood. Egmont Paper No. 67, June 2014

Introduction. Russia’s annexation of the Crimea and subsequent meddling in Ukraine does not constitute a game-changer. It is just a reminder that at least since the war with Georgia in 2008 Russia has been and still is playing the same game: a “game of zones���, aimed at (re)establishing an exclusive sphere of influence. Many of us Europeans had forgotten that, or had pushed it to the back of our minds, preferring to believe that we were not engaged in a zero-sum game in our eastern neighbourhood. While we were dealing with Ukraine, we tended also to forget the crises still going on in our southern neighbourhood, in Libya, Mali, Syria and now Iraq. Spilling over from Syria, extremist militias may establish their own “zone” in the Middle East, which would de-stabilize the entire region. In order to prevent that game-changer from materializing, another game-changer may be necessary: a rapprochement with Iran. Europe must assume responsibility for security in its entire neighbourhood, both east and south. The challenge is great – but so are Europe’s means.

Fault development and interaction in distributed strike-slip shear zones: an experimental approach

Analogue model experiments using both brittle and viscous materials were performed to investigate the development and interaction of strike-slip faults in zones of distributed shear deformation. At low strain, bulk dextral shear deformation of an initial rectangular model is dominantly accommodated by left-stepping, en echelon strike-slip faults (Riedel shears, R) that form in response to the regional (bulk) stress field. Push-up zones form in the area of interaction between adjacent left-stepping Riedel shears. In cross sections, faults bounding push-up zones have an arcuate shape or merge at depth. Adjacent left-stepping R shears merge by sideways propagation or link by short synthetic shears that strike subparallel to the bulk shear direction. Coalescence of en echelon R shears results in major, through-going faults zones (master faults). Several parallel master faults develop due to the distributed nature of deformation. Spacing between master faults is related to the thickness of the brittle layers overlying the basal viscous layer. Master faults control to a large extent the subsequent fault pattern. With increasing strain, relatively short antithetic and synthetic faults develop mostly between old, but still active master faults. The orientation and evolution of the new faults indicate local modifications of the stress field. In experiments lacking lateral borders, closely spaced parallel antithetic faults (cross faults) define blocks that undergo clockwise rotation about a vertical axis with continuing deformation. Fault development and fault interaction at different stages of shear strain in our models show similarities with natural examples that have undergone distributed shear.