Linking the Anatolian microplate rigid motions to the 1999 Mw = 7.5 Izmit earthquake rupture

It is typically assumed that the occurrence of large earthquakes along the margins of tectonic plates does not impact on their rigid motions. However, for tectonic units of small size (i.e. for microplates), the viscous resistance at the plate base, and thus the torques needed to change their rigid motions, are significantly smaller than those needed for medium/large-size plates. In fact, a recent study that makes use of numerical simulations of synthetic microplates indicates that it is theoretically possible to link the temporal evolution of geodetically-observed microplate motions to the buildup and release of stresses associated with the earthquake cycle.

Here, we focus on the motion of the Anatolian microplate. We extract its rigid motion from GPS time series spanning the time around the 1999 M_W = 7.5 Izmit earthquake. We select those GPS stations that are sufficiently away from plate boundaries, such as the North Anatolian Fault, the East Anatolian Fault and the Western Anatolia Extensional Province. Then, we attempt linking the temporal evolution of the Anatolian microplate rigid motion to the stresses associated with the 1999 M_W = 7.5 Izmit earthquake rupture. The novelty of our approach lies in the fact that, in contrast to current models of the earthquake cycle, we connect earthquake stresses to changes in plate rigid motions and not to the crustal deformation in the vicinity of earthquake-prone faults.