Geo-hazard assessment of the NEOM area, Northwest Saudi Arabia, using seismological and potential field data

Abstract

The active tectonics of the Gulf of Aqaba (Red Sea) may affect the newly established NEOM megacity in northwestern Saudi Arabia. Using seismological and potential field data, this study aimed to evaluate the major tectonic trends around NEOM area and their hazard impacts on the NEOM area. In particular, aeromagnetic and gravity data were used to explore the major tectonic trends that may affect this area. The interpreted tectonic trends are directed mainly along the NNE and NNW, as well as NW and EW tectonic trends. A good correlation was found between the distribution of the earthquake epicenters (Mw ≥ 4) and the interpreted tectonic trends. Moreover, the distribution of epicenters was congruent with the fault trends obtained from the potential field data, implying that the observed fault trends can generate earthquakes. For the seismic hazard assessment, the source parameters and expected ground motions of two moderate earthquakes that occurred in the Gulf of Aqaba in 2015 and 2016 were analyzed. Assuming an omega-squared source model, a grid search method was applied to fit the amplitude spectra of the S-wave group over the model parameters that were used to compute Mo values of 4.06E + 23 and 2.14E + 23 Nm, corresponding to Mw of 5.0 and 4.8, fault radii of 831 m and 835 m, and stress drop (Δσ) values of 7.72 and 4.01 MPa for the 2015 and 2016 earthquakes, respectively. An empirical Green’s function summation technique was performed to simulate high-frequency ground motions expected for future large earthquakes, demonstrating the influence of such earthquakes on the study area. For a Δσ value of 10 Mpa (characteristic of past earthquakes in the Gulf of Aqaba), peak ground accelerations of ∼ 5.6 and 5.53 m/s2 are to be expected for future earthquakes with Mw 7.0 in the epicentral regions of the 2015 and 2016 earthquakes.