Relationships between volcanic patterns and neotectonics in Eastern Anatolia from analysis of satellite images and DEM

The late Neogene to Quaternary volcanism in Eastern Anatolia is related to the Arabia-Eurasia convergence but a clear deformation pattern has not yet been established in this region. We have used the distribution and shape of volcanoes and fault geometry as indicators of the tectonic regime. Volcanic edifices and related faults were analyzed in vertical view using SAR-ERS, Spot images and a Digital Elevation Model (DEM). In several places, adjacent volcanoes that form linear clusters or elongated volcanoes are clearly rooted on vertical tension fractures. These are compatible with horizontal sigma(3), striking 90 degrees N, associated with sigma(1) horizontal (strike-slip regime) or vertical (extensional regime). We mapped the recent faults that are directly associated to volcanoes. Volcanic vents are related to tail-crack, horsetail or releasing bend structures. In this work, it has been possible to define the ESE-striking, 270-km-long Tutak-Hamur-Caldiran fault that forms a releasing bend testifying to right-lateral motion. Extension is well documented for few places but no recent fold has been observed. Since 8 Ma, the tectonic system is principally strike-slip. Most of the tension fractures being 2 to 10 km in length, so we infer that they affect only part of the crust. Most strike-slip fault zones are of several tens to a few hundred kilometers long and thus not of lithospheric scale. Therefore, the channels used by the magma to reach the surface are crustal structures. (C) 1998 Elsevier Science B.V. All rights reserved.