Coseismic and postseismic surface deformations of the Mw 7.2, October 23, 2011 Van Earthquake (Turkey) from GPS measurements

Coseismic and postseismic surface displacements due to the Mw 7.2, October 23, 2011 Van (eastern Turkey) earthquake were obtained from campaign and continuous GPS data sets. Coseismic field was deduced by GPS surveys within one week after the event with the contribution of available continuous sites in the far field. The coseismic displacements that reach about 50 cm in horizontal and 11 cm in vertical (uplift) direction confirm the seismological and field observations that the event is associated with reverse faulting with a minor left-lateral strike slip component on a NE-SW trending and northward dipping fault. A campaign GPS network consisting of 8 benchmarks was established to monitor the near field postseismic surface deformation about one month after the earthquake. GPS measurements from three campaigns following the earthquake in November 2011, January 2012 and June 2012 indicate that the early postseismic deformation is most probably due to shallow afterslip that appears to decrease exponentially with time. Space-time evolution and the nature of the postseismic deformation will be better revealed by additional campaign and continuous GPS measurements for the next three years. Keywords: 2011 Van earthquake, GPS, Co- and postseismic deformation