HR: 0800h
AN: T51C-1354    [Abstracts]
TI: Extension in NW Iran inferred from GPS enlightens the behavior of the south Caspian Basin
AU: Masson, F
EM: fmasson@dstu.univ-montp2.fr
AF: Laboratoire Dynamique de la Lithosphere, Universite Montpellier II - CNRS, Place E. Bataillon, Montpellier, 34095 France
AU: * Chery, J
EM: chery@dstu.univ-montp2.fr
AF: Laboratoire Dynamique de la Lithosphere, Universite Montpellier II - CNRS, Place E. Bataillon, Montpellier, 34095 France
AU: Van Gorp, S
EM: vangorp@dstu.univ-montp2.fr
AF: Laboratoire Dynamique de la Lithosphere, Universite Montpellier II - CNRS, Place E. Bataillon, Montpellier, 34095 France
AU: Tavakoli, F
EM: f-tavakol@ncc.neda.net.ir
AF: Geodynamic Department, National Cartographic Center, Po. BOX 13185-1684, Meraj Ave, Tehran, 99999 Iran (Islamic Republic of)
AU: Tatar, M
EM: mtatar@iiees.ac.ir
AF: International Institute of Earthquake Engineering and Seismology, Farmanieh, Dibaji, Arghavan St., No. 27, Tehran, 19531 Iran (Islamic Republic of)
AU: Nankali, H
EM: h-nankali@ncc.neda.net.ir
AF: Geodynamic Department, National Cartographic Center, Po. BOX 13185-1684, Meraj Ave, Tehran, 99999 Iran (Islamic Republic of)
AB: Large scale velocity field of Iran has been obtained from recent repeated GPS surveys (Vernant et al. 2004) and suggests about 7 mm/yr of right-lateral displacement for the NW-SE faults in the Tabriz region (NW Iran). These faults are well-known for their large historical seismicity (Berberian & Yeats, 1999). East of NW Iran, the south Caspian basin (SCB) is a relatively aseismic block involved in the collision zone between Eurasia and Arabia. The SCB is expected to be relatively rigid. In order to 1- localize more precisely the right-lateral movement observed in NW Iran and to 2- better constrain the relative motion of the SCB with respect to NW Iran, we have installed and measured a dense GPS network in NW Iran, from Central Iran to the Turkish, Armenian and Azerbaijan borders. 19 points has been installed and measured in the framework of French Iranian cooperation. All sites have been surveyed at least three times in September 2002, 2003 and 2004 during 48 hours. Some sites have been measured four, five or six times since 1999. Surprisingly, an unexpected result has been obtained: the NW Iran right-lateral movement is combined with SW-NE extension north of the Tabriz fault (TF). On the base of our GPS results in NW Iran, we address three aspects of the Iranian tectonics. (1) The right-lateral movement observed in NW Iran is concentrated on the TF which suffers about 7 mm/year of right-lateral movement. This rate is in agreement with a recurrence interval time of 250-300 years proposed from historical seismicity studies. (2) About 8 mm/year of extension is observed north of the TF, between the TF and the Azerbaijan border, within the Talesh. This extension is in agreement with the existence of a southwestward subduction of the SCB. (3) The Talesh and Alborz mountain ranges are not a single continuous structure wrapping the Caspian shoreline because of the northward extension of Central Iran up to the southern Caspian shoreline documented by the velocity of ATTA.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8110 Continental tectonics: general (0905)
SC: Tectonophysics [T]
MN: Fall Meeting 2005