World Stress Map Conference - International Lithosphere Program ...

Thursday, October 16 th
Oral Session IV: Numerical modelling of contemporary stress and strain observations
Contemporary mantle flow and tectonic stress beneath the
Central Mediterranean based on integrated analysis of
seismic, heat flow, geodetic and gravity data and numerical
modelling
Alik Ismail-Zadeh
Geophysical Institute, Karlsruhe University, Germany
Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
Alik.Ismail-Zadeh@gpi.uka.de
Abdelkrim Aoudia
Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
Giuliano Panza
Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
Department of Earth Sciences, University of Trieste, Italy
Density heterogeneities and geometry of the lithosphere beneath the Central Mediterranean
influence the lithospheric deformation, mantle flow, and tectonic stress state. To estimate the
contribution of the buoyancy forces to present dynamics of the region, three-dimensional
finite element models of contemporary uppermost mantle flow are developed, and tectonic
stress predicted by the models is analysed. We use density models for the crust and uppermost
mantle derived from S-wave seismic velocities and further constrained by observed gravity
data. Several viscosity models are tested in the modelling to explore the viscosity effect on
stress pattern and mantle flow. The viscosity models are constrained by regional heat flow
data and specific postseismic deformation studies. The movement of the uppermost crust
predicted by the most preferred model is consistent with the NE-oriented motion of the
lithosphere and is in an agreement with GPS data. The flow patterns of lower crustal and
uppermost mantle predict the NW-oriented movements beneath the SE part of the Adriatic
Sea region; the NE-subduction beneath the Dinarides; upwelling and opening beneath the
Tyrrhenian Sea; the western movement of the Ionian Sea subplate; and subduction beneath
the western Calabria region. The modelled features of the movements are consistent with the
observations. Our models predict the distinct compressional regime along the NE part of the
Italian peninsula and to the east of Sicily, and the tensional regime beneath the Tyrrhenian
Sea, Umbria-Marche region, and Ionian Sea. The predicted tectonic stresses in the lithosphere
of northern and central Apennines are correlated with stress patterns derived from the WSM
data. Based on the model results, we conclude that the buoyancy forces play an important role
in the contemporary tectonics of the region.
66 3 rd World Stress Map Conference, 15.-17. October 2008 in Potsdam