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Abstract: What is the origin of the widespread Cenozoic volcanism on the Arabian Peninsula? How can we reconcile the long-term tectonic evolution of the Arabian Plate with the current surface geology in Saudi Arabia? What are the implications of deep Earth structure for the potential future use of geothermal energy resources in the Kingdom? The Earth structure underneath Saudi Arabia remained rather elusive until about a decade ago when the Saudi Geological Survey began installing a dense seismic network across the Kingdom. Whilst early studies provided a first-order understanding of crustal and upper-mantle structure based on small datasets (e.g. Mooney et al., 1985; Julia et al., 2003; Al-Damegh et al., 2005; Chang and Van der Lee, 2011), recent works focused on small regions of interest (e.g. Hansen et al, 2007, 2013; Koulakov et al 2015, 2016). However, a comprehensive large-scale three-dimensional model of the deep subsurface structure below the Arabian Plate has been missing.
Using a comprehensive dataset based on the dense Saudi National Seismic Network (SNSN, operated by the Saudi Geological Survey, SGS), adding also seismic measurements from neighboring countries, this talk presents a three-dimensional model of the lithosphere and asthenosphere below Saudi Arabia. I combine results from our collaborative research at KAUST during the past five years and discuss the shear-wave velocity structure of the crust and upper mantle, potential asthenospheric flow, and the thickness of the mantle-transition zone underneath the Arabian Plate. These deep-seated structures have profound effects on the current volcanism in western Saudi Arabia and determine the heat-flow near the Earth's surface, pinpointing to regions that may be conducive to develop geothermal energy as an alternative and renewable energy source for the Kingdom.
Biography: Prof. P. Martin Mai is a Professor of Geophysics in the Physical Sciences and Engineering Division at KAUST. He joined KAUST as a founding faculty member in June 2009, after being a post-doc & research scientist at ETH Zurich (2002 – 2009) and completing his Ph.D. at Stanford University (2001). Professor Mai’s research focuses on the physics of earthquakes and the complexity of earthquake phenomena, with emphasis on earthquake-source imaging, dynamic rupture simulations, and earthquake mechanics. His work extends to strong ground-motion properties and near-source seismic wave-field simulations that include wave scattering in heterogeneous media. His work thus spans from fundamental earthquake physics to earthquake-engineering applications, by quantifying earthquake source complexity for physics-based ground-motion and tsunami simulations using high-performance computing.
The second major thrust in Prof. Mai research uses seismological observations to investigate Earth structure. Using seismic data recorded in Saudi Arabia, Prof. Mai and his collaborators image the structure of the Earth crust and upper mantle underneath the Arabian plate, as these affect our ability to locate earthquakes and understand their tectonic origin. These fundamental studies facilitate further seismological research in Saudi Arabia, as well as studying the geodynamic context of the Arabian plate and the Red Sea. With their own portable seismic broadband stations, Prof. Mai and his team deploy temporary seismic networks, recently in northern Tanzania and currently in the Gulf of Aqaba region for local high-resolution seismic studies.