An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities

Abstract : We present the most extensive and up-to-date unified GPS velocity field for Iran. We processed the data collected during 10 yr (2006–2015) from the Iranian Permanent GNSS Network (IPGN) and combined them with previously published velocity solutions from the GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain-rate map for this region and we designed a block model based on the main geological, morphological and seismic structures. Comparison between both approaches suggests similar results and allows us to present the first comprehensive first-order fault-slip-rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. However, we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematics of the faults north of the Makran in the Jazmurian depression. Indeed, although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E–W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio; hence, the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.