Apr 2023
On February 6, 2023, two powerful earthquakes of magnitude 7.8 and 7.6 rocked south-central Türkiye and northern Syria, strongly affecting the regions around Gaziantep, Kahramanmaraş, Malatya, and Hatay. The epicenter of the first mainshock is located close to the East Anatolian Fault (EAF), while the second large earthquake 9 hours later initiated ~90 km north of the first mainshock on an east-west trending fault. Aftershocks delineate fault lengths of ~350 km and ~170 km, respectively. The death toll surpassed 50’000 victims in Türkiye and 7’000 in Syria, rendering these earthquakes the deadliest in Türkiye in modern history.
KAUST scientists responded to media requests soon after the quakes happened and began collecting data and relevant information. Using seismic and satellite data, we performed first-order analyses to quantify surface-fault offsets, studied the earthquake rupture process, and examined the ground-shaking patterns to shed light on the reason for the immense destruction caused by these two earthquakes. The first earthquake started on an EAF-branch and then ruptured the EAF bilaterally, lasted for ~80 sec and created surface-offsets of up to 6 m. The second event had a duration of ~35sec, ruptured bilaterally and generated up to 8 m surface displacements. Strong-motion recordings showed PGA values up to 2g in the first mainshock, with particularly severe shaking in the Hatay Province, where multiple stations recorded ground-accelerations of over 0.5 g. Specific rupture-process behavior and local site amplifications were likely responsible for very strong ground-shaking locally.
The talk begins with a short review of the tectonic context of the East Anatolian Fault, with its large earthquakes in the past, and then provides an overview on how scientist quantify earthquake hazards. I also briefly address the question if such earthquakes can occur elsewhere, for example in Saudi Arabia. Furthermore, I will not only illustrate the results of our fast-response collaborative research to understand these earthquakes and their tragic consequences. I will also attempt to describe the experience as a scientist to suddenly be exposed to mass-media, urgent live TV appearance, and public attention.
Prof. P. Martin Mai is Professor of Geophysics in the Physical Sciences and Engineering Division at KAUST. He joined KAUST as founding faculty member in June 2009, after a PhD at Stanford University (2001) and positions as post-doc and research scientist at ETH Zurich (2002 – 2009).
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. Prof. Mai’s research 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. Another line of Prof. Mai research uses seismological observations to identify & locate earthquakes and to image the structure of the Earth crust and upper mantle underneath the Arabian plate to better understand the tectonic context of the Arabian plate and the Red Sea. Furthermore, Prof. Mai is active in the research field of geothermal energy, with a focus on identifying and developing low-temperature geothermal reservoirs for direct use (desalination, district cooling/heating) in the syn-rift sedimentary basins along the Red Sea coast in Saudi Arabia.
Currently, Prof. Mai is the Editor-in-Chief for the Bulletin of the Seismological Society of America (BSSA), the premier international journal in earthquake seismology (established in 1911). From 2018 to 2021, he served as the Associate Dean (Students) for the PSE-Division at KAUST.