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Yerevan, American Samoa

Avagyan A.,Armenian National Academy of Sciences | Sosson M.,University of Nice Sophia Antipolis | Karakhanian A.,GEORISK Scientific Research Company | Philip H.,Montpellier University | And 4 more authors.
Geological Society Special Publication | Year: 2010

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). © 2010 The Geological Society of London. Source


Karakhanyan A.,Armenian National Academy of Sciences | Avagyan A.,GEORISK Scientific Research Company | Sourouzian H.,German Institute of Archaeology
Special Paper of the Geological Society of America | Year: 2010

Our studies in the temple of Amenhotep III, conducted under the project on Excavation and Conservation at Kom el-Hettan, provide new information about the seismic history of ancient Thebes. Distinct signs of liquefaction are revealed at the temple site. Trenches exhibit sand dikes and sills that formed extension cracks through the mechanism of lateral spreading. Clear effects of liquefaction by lateral spreading were discovered in other monuments on the west bank of the Nile. Application of historical, archaeological, and geological methods enables us to constrain the time of the earthquake responsible for the damage in the west bank temples to between 1200 and 901 B.C. Furthermore, we find no signs of an earthquake in 27 B.C. The foot of the Thebes Plateau may conceal a basement fault with combined vertical and horizontal slip kinematics. The fault located to the southeast, near an ancient sanctuary, may correspond to either seismogenic fault surface rupture, or a secondary seismic effect manifested as subordinate rupture and ground failure. © 2010 The Geological Society of America. All rights reserved. Source


Karakhanyan A.,Institute of Geological science | Vernant P.,Montpellier University | Doerflinger E.,Montpellier University | Avagyan A.,Institute of Geological science | And 10 more authors.
Tectonophysics | Year: 2013

We present the 1998-2009 GPS-derived velocity field for the Armenia region based on a survey-mode observation network of 31 GPS sites. We combine our results with previous GPS studies of the region to better assess the deformation of the Lesser Caucasus and Kura basin region. The results show that the Kura basin and the Lesser Caucasus regions are two different blocks, and that the main fault (Pambak-Sevan-Sunik) between these two regions has a right-lateral slip rate of 2 ± 1. mm/yr. This is consistent with morphotectonic estimates and suggests a fairly constant slip rate over the last 120-300. ka. The right-lateral slip rate on one of the southern branch of the Pambak-Sevan-Sunik fault is lower than 1. mm/yr and the good agreement with a geologically estimated slip rate suggests a constant slip rate over the last 1.4. Myr. The Sardarapat and Akhurian faults experience some shortening. This shortening is consistent with some independent geological estimates and shows the Arabian push. However, NNW-SSE-orientated faults have an extensional fault normal component instead of the expected shortening due to the Arabia-Eurasia convergence. This substantial extensive strain, and the sharp azimuth change of the velocity vectors between the Arabia promontory and the Lesser Caucasus suggest that processes other than "extrusion", possibly related to old subduction or delamination, contribute to the geodynamics of the region. © 2013 Elsevier B.V. Source

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