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. Volcani c edifices and related faults were analyzed in vertical view using SAR-ERS, Spot images and a Digital Elevation Model (DEM). In several places, adjace nt volcanoes that form linear clusters or elongated volcanoes are clearly r ooted on vertical tension fractures. These are compatible with horizontal s igma(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 t ail-crack, horsetail or releasing bend structures. In this work, it has bee n possible to define the ESE-striking, 270-km-long Tutak-Hamur-Caldiran fau lt that forms a releasing bend testifying to right-lateral motion. Extensio n is well documented for few places but no recent fold has been observed. S ince 8 Ma, the tectonic system is principally strike-slip. Most of the tens ion 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 f ew hundred kilometers long and thus not of lithospheric scale. Therefore, t he channels used by the magma to reach the surface are crustal structures. (C) 1998 Elsevier Science B.V. All rights reserved.