HR: 1340h
AN: G13A-0801    [Abstracts]
TI: GPS Observations Indicate Postseismic Deformation in the Vrancea Region, Romania
AU: * Vermeersen, B L
EM: b.vermeersen@lr.tudelft.nl
AF: DEOS - Delft Univ. Technology, Kluyverweg 1, Delft, 2629 HS Netherlands
AU: van der Hoeven, A G
EM: A.G.A.vanderHoeven@lr.tudelft.nl
AF: DEOS - Delft Univ. Technology, Kluyverweg 1, Delft, 2629 HS Netherlands
AU: Spakman, W
EM: wims@geo.uu.nl
AF: Fac. Geosciences - Utrecht Univ., Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: van Hove, J
EM: J.vanHove@student.tudelft.nl
AF: DEOS - Delft Univ. Technology, Kluyverweg 1, Delft, 2629 HS Netherlands
AU: Riva, R E
EM: riccardo@dst.units.it
AF: DEOS - Delft Univ. Technology, Kluyverweg 1, Delft, 2629 HS Netherlands
AU: Riva, R E
EM: riccardo@dst.units.it
AF: Dept. Earth Sciences - Univ. Trieste, via E. Weiss, 1, Trieste, 34127 Italy
AU: Ambrosius, B A
EM: B.A.C.Ambrosius@lr.tudelft.nl
AF: DEOS - Delft Univ. Technology, Kluyverweg 1, Delft, 2629 HS Netherlands
AU: Mocanu, V
EM: mocanu@gg.unibuc.ro
AF: Dept. Geophysics - Univ. Bucherest, str. Traian Vuia nr. 6, sect. 1, Bucharest, 70139 Romania
AU: Schmitt, G
EM: schmitt@gik.uni-karlsruhe.de
AF: GIK - Univ. Karlsruhe, Englerstrasse 7, Karlsruhe, 76128 Germany
AU: Nutto, M
EM: nutto@gik.uni-karlsruhe.de
AF: GIK - Univ. Karlsruhe, Englerstrasse 7, Karlsruhe, 76128 Germany
AU: Russo, R M
EM: ray@earth.northwestern.edu
AF: Dept. Geological Sciences - Northwestern Univ., 1850 Campus Drive, Evanston, IL 60208-2150 United States
AB: The Vrancea region in the South-East Carpathians of Romania is a seismically active area related to past or ongoing lithosphere subduction. One of the outstanding questions is whether the subducting slab is attached, detached or in the process of being detached from the overlying lithosphere. GPS campaigns of 3-D crustal displacements in this region, performed by ISES (Netherlands) in collaboration with SFB-461 (Germany) and the University of Bucharest (Romania), are expected to assist in solving this issue. Measurements have been performed in this area since 1995 and the current GPS network consists of more than 50 campaign points and six permanent GPS stations. However, ongoing deformation related to large ($M_w$ $>$ 7) earthquakes that struck the Vrancea region in 1977, 1986 and 1990 could have a considerable contribution to GPS-observed displacement rates. This so-called postseismic deformation results from viscoelastic relaxation of crustal and shallow upper-mantle low-viscosity zones due to the redistributed stress and strain after faulting. Results from the GPS campaigns combined with numerical postseismic deformation modelling indicate that postseismic relaxation is even the dominant mechanism for present-day horizontal crustal displacements in the Vrancea region. This suggests small ($<$ 1 - 2 mm/yr) to insignificant ongoing plate convergence. Vector solution directions are not very sensitive to the earth model, while magnitudes agree for a seismically and tectonically consistent earth model for the Vrancea region. This has important implications for interpreting neotectonic processes in the Carpathians.
DE: 8110 Continental tectonics--general (0905)
DE: 1206 Crustal movements--interplate (8155)
DE: 1208 Crustal movements--intraplate (8110)
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting