TWO DIMENSIONAL VELOCITY FIELD OF THE IRANIAN PLATEAU

Long-term crustal flow of the Iranian Plateau is computed using a kinematic model. Three independent data sets (geometry of the seismically active faults mapped in prior geological studies, geodetic benchmark velocities, and principal stress directions) are combined using a finite-element model to better understand regional geodynamics of the Iranian Plateau. We are successful to find the best kinematic model, in which all the data sets are fitted at a RMS level of 1.0 datum standard deviation. The best fitted model, for the first time, provides the velocity field over the Iranian Plateau from all available kinematic data. Spatial distribution of displacement rates within the plateau shows a mixed pattern, in which semi-rigid blocks (e.g. Lut Desert Block and South Caspian Block) are embedded in a deformation zone (e.g. the Zagros and Alborz Mountain Belt). Our estimated rates are consistent with the past earthquakes, and are in the range of previous published rates, in which geodetic benchmark velocities are merely analyzed using different modeling techniques. Sharp changes of displacement rates in some region (e.g. northeastern Iran) show high strain rates, and hence using elastic block modeling seems not to be suitable for fault slip rate estimation. Moreover, the obtained results are useful to calculate the strain rate field, which could be considered as an indicator for undiscovered or/and unmapped faults.

کلیدواژه ها:

Slip-rate ، PSHA ، Iranian Plat Eau