Source parameters for the M_w = 6.6, 03 February 2002, Çay Earthquake (Turkey) and aftershocks from GPS, Southwestern Turkey

The 03 February 2002 Çay Earthquake (M_w ~6.7) occurred on the fault segment between Eber and Akşehir Lakes followed by a large aftershock (M_w ~ 5.6) near the western end of the fault and two sequential aftershocks. We computed the coseismic surface displacements from static GPS measurements to determine the fault geometry parameters and uniform slip components. The coseismic displacements were obtained through combining the regional pre-earthquake and post-earthquake GPS data. Fault geometry and slips were acquired through the inversion of GPS data modeling the events as elastic dislocations in a half-space and assuming all four events took place on the same fault plane. Results suggest that one-segment fault of ~33km length and dipping ~43° northward suffices to model the dislocation, assuming uniform slip distribution with 0.51m dip slip, 0.26m left-lateral slip extending to a depth down to ~11.5km which is consistent with seismological evidence. The results also verify the normal faulting in the eastern flank of Isparta Angle which has long been assumed as a thrusting structure. While the available data cannot identify the four individual events on the same day, an attempted distributed slip model differentiates dip slip and left-lateral slips near the hypocenter with maximum values of ~1 and 0.6m, respectively.