Abstract: The most significant earthquake hazard in Saudi Arabia is along the coast of Gulf of Aqaba and near Strait of Tiran (GAST). The hazard is due earthquakes on the Dead Sea fault system, which extends from the Red Sea, through Strait of Tiran, along the entire Gulf of Aqaba and all the way north to Turkey. Many devastating earthquakes have occurred on the Dead Sea fault during the past 2000 years, with the last major earthquake occurring in the middle of Gulf of Aqaba in 1995 (magnitude 7.3), causing several fatalities and considerable damage in Nuweiba in Egypt and Haql in Saudi Arabia. However, the earthquake released only a portion of the earthquake moment that has accumulated in the GAST area during the past several hundred years, so more major earthquakes can be expected. The recent decisions of building a bridge between Saudi Arabia and Egypt and the new city of NEOM has put this area in focus, e.g., with respect to earthquake hazard. The planned bridge will span Strait of Tiran and go across the Dead Sea fault, which is capable of producing earthquakes larger than magnitude 7, multi-meter fault offsets, and violent shaking. To improve our understanding of the tectonics and the level of earthquake activity in the GAST area, we are working on an interdisciplinary project aimed at constraining better the location and geometry of active faults in the gulf and its overall tectonics, as well as obtaining new information about how frequent and how large major earthquakes in the area likely are. We have acquired new high-resolution multibeam bathymetric data and are re-analyzing decades of earthquake data to map active faults within the gulf. To get better information about the structure and activity of normal faults bounding the gulf’s pull-a-part basins, we have run a seismic survey along a 7 km long profile, crossing one of the faults, and dated samples from uplifted coral terraces along the gulf. In addition, we have installed and remeasured a geodetic GPS network to constrain the moment accumulation rate in the area and collected sediment cores from the seafloor for evidence of pre-historic earthquakes. Finally, we are running scenario calculations to estimate expected shaking levels in future major earthquakes on the GAST faults. Together the results will significantly improve knowledge of the active tectonics and earthquake activity in the GAST area and provide valuable information for future seismic hazard assessments.
Bio: Prof. Sigurjón Jónsson grew up among volcanoes and earthquakes in northern Iceland and went on to study Geophysics at the University of Iceland, from where he received both a bachelors and a masters degree in the subject. He earned his doctoral degree in Geophysics and a master’s degree in Electrical Engineering from Stanford University in 2002. After graduation, Prof. Jónsson was a postdoctoral researcher at Harvard University and a senior researcher and lecturer at the Institute of Geophysics, ETH Zurich, Switzerland. From 2009 he has been with the ErSE program at KAUST, first as Associate Professor of Geophysics and since 2016 as Professor. During his career, he has been interested in volcanic and seismic processes, and used crustal deformation observations (satellite radar interferometric imaging in particular) to gain insight into the subsurface activity. At KAUST, Prof. Jónsson leads the crustal deformation and InSAR research group (http://cdi.kaust.edu.sa).