A compilation of more than one thousand stress indicators (which include in situ stress measurements, focal mechanisms, microtectonic and other geological data) allowed us to reconstruct the modern stress field in the Mediterranean region and the surrounding area. Average stress directions at different scales have been reconstructed by means of a linear interpolation method. This method takes into account the distribution, scale and quality of stress data. The results of the interpolation at plate scale, allow us to recognize slightly deformed regions such as the northwestern European platform, where average maximum horizontal stress direction is oriented roughly NNW-SSE, subparallel to absolute and relative plate velocity directions. Other regions such as the Caucasus, Alps and Pyrenees, where recent tectonic deformation and seismicity are present, display important variations of stress directions. The reconstruction of the average stress directions at different scales within the French Alps pointed out that the average stress field pattern may vary from one scale to another. Nevertheless, variations of stress directions at a given scale are consistent with the kinematics of faults of the same scale.

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Detailed SPOT image analysis which completed field data and a microseismicity study was done on the central Caucasian mountain belt (Georgia, Armenia, and eastern Turkey), north of the front of the Arabian collision in order to clarify the relationships between compression, extension, and volcanism. In fact, this region is characterized by relatively complex active tectonics, associating both N-S compressive (E-W thrusts and folds) and E-W extensional (N-S normal faults and dikes) structures accompanied by considerable Neogene to Quaternary volcanism, and NE-SW left-lateral and NW-SE rightlateral strike-slip faults. These different structures are all intricately imbricated and can be observed at different scales. The general lay out implies an important variation in the stress state; for instance, this passes from a N-S compression in the S pitak earthquake fault zone to an E-W extension at the Aboul-Samsar volcanic axis. These results agree well with the N-S convergence between Arabia and Eurasia, and the E-W lateral expulsion of the Anatolian and Iranian blocks. A detailed cartographic network of active structures was drawn and their kinematic relationships were specified. In places, recent offsets on strike-slip faults were estimated at about 500 to 1000 m. Suitable sites for future determination of fault velocity displacements were also selected. This study shows that some strike-slip faults behave partly like faults which transform the E-W extension of the N-S striking normal faults into a N-S compression along the E-W thrusts. One of the characteristics of this region is the continuous important volcanic activity at least from the Jurassic until now. This persistence evidences a lithospheric thinning, which remained in spite of the recent Arabian-Eurasian collision because of the E-W extension linked to the opposite lateral expulsion of the Anatolian and Iranian blocks. This geodynamic evolution can explain the juxtaposition and superimposition of volcanic structures and thrusts in a general compressive context.

The stress indicators describing the recent (provided by active tectonics framework) and palaeo-stress (provided by micro-fault kinematics and volcanic cluster) patterns show the scale and temporal changes in stress states since the beginning of Arabian–Eurasian collision. The recent stress derived from the active fault kinematics in the Lesser Caucasus and adjacent area corresponds to a strike–slip regime with both transtension and transpression characteristics. The kinematics of active structures of various scale are conditioned by tectonic stress field with general north–south compression and east–west extension. The distribution of Neogene to Quaternary volcanic cluster geometries and micro-fault kinematic data evidence the time and orientation variability of the stress field since the beginning of the Arabian–Eurasian collision. In addition to the general north–south compression orientation, two other – NW–SE and NE–SW – secondary orientations are observed. The first one was dominant between the Palaeogene and the late Early Miocene and the second one has prevailed between the Late Miocene and the Quaternary. Since the continental collision of Arabia with Eurasia the tectonic stress regime in the Lesser Caucasus and adjacent area changed from compression (thrusting and reverse faulting) to transtension-transpression (strike–slip faulting with various vertical components)