The Rigidity of the Western Arabian Margin: Extensional Strain Rate Field from GPS Networks

Previous analysis of the deformation field of the Arabian margin using then the available network of Global Navigation Satellite System (GNSS) stations found that an assumption of a rigid Arabia satisfied the observations as reported by ArRajehi et al. ( Tectonics 29, no. 3, 2010 ). However, an Mw 5.4 intra-plate earthquake occurred in 2009 in the Alshaqqah Harrat as discussed by Pallister et al. ( Nature Geoscience 3, no. 10:705, 2010 ) suggesting that there is ongoing active deformation within the western Arabian margin. We evaluate the Arabian margin deformation field using an expanded network totaling 87 GPS stations distributed within Saudi Arabia. With the addition of these GPS stations, we found evidence of extensional strain within the Arabian margin, in regions that were unsampled by the previous geodetic networks. Although, due to the short time series, the signal at these new GPS sites is very close to the limit of the resolution, this study provides the first indication, derived from GPS velocities, of the location and extent of active internal deformation within the Arabian plate.