Have the 1999 Izmit–Düzce earthquakes influenced the motion and seismicity of the Anatolian microplate?

Abstract

SUMMARY In the current plate tectonics paradigm, relative plate motions are assumed to remain unperturbed by temporal stress changes occurring during the seismic cycle, whereby stress slowly built up along tectonic plate boundaries is suddenly released by rapid fault slip during earthquakes. However, direct observations that could challenge such a tenet have not been identified so far. Here we show that the rigid motion of the whole Anatolian microplate, measured using space geodetic techniques, was altered by the stress released during the 1999 Izmit–Düzce earthquakes, which ruptured along the North Anatolian Fault. This kinematic change requires a torque change that is in agreement with the torque change imparted upon the Anatolian microplate by the Izmit–Düzce coseismic stress release. This inference holds across realistic ranges of data noise and controlling parameters, and is not hindered by active deformation in western Anatolia. These results suggest the existence of a whole-plate kinematic signal associated with the stress released by large earthquakes.