Romain Jolivet on the 2023 Turkey-Syria Earthquakes
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Romain Jolivet studies active faults and the relative motion of tectonic plates. His research focuses on the relationship between slow, aseismic slip that occurs “silently” between earthquakes and the rapid slip accompanying earthquakes. As he describes in the podcast, he uses interferometric synthetic aperture radar (InSAR) images from radar satellites to examine surface deformation over wide areas at meter-scale resolution. InSAR images of the 2023 Turkey-Syria earthquakes reveal complicated slip patterns occurring on well-recognized plate boundary faults as well as on hitherto ignored faults.
Romain Jolivet is a Professor of Geoscience at the École normale supérieure in Paris.
Podcast Illustrations
Tectonic setting of the Anatolian plate. The Mediterranean Basin, including Anatolia and the Aegean Sea. Red lines mark the major faults that accommodate the westward movement of Anatolia. The barbed black lines show subduction zones, the yellow circles show earthquakes of magnitude 3 and above, and the red triangles show volcanoes.
Close-up view of the Eastern Mediterranean region. Westward movement of Anatolia (light brown region) results from the collision between Africa, Arabia, and Eurasia as well as the Hellenic subduction zone to the south and rollback (i.e., retreat) of the subducting African plate. The Aegean Sea (turquoise region) is undergoing rapid extension, thought to be driven by slab rollback. Slab rollback is discussed in the previous podcast with Laurent Jolivet, and animated visualizations appear on that episode’s web page. The main movement of the February 2023 earthquakes occurred along the East Anatolian Fault (EAF) and the North Anatolian Fault (NAF). The Hellenic volcanic arc is colored purple. Black arrows indicate the local velocity relative to Eurasia. The black lines indicate subduction zones. The rectangle indicates the region covered by the map of the East Anatolian Fault segments shown below. BZS, Bitlis-Zagros Suture; CAFZ, Central Anatolian Fault Zone; DSTF, Dead Sea Transform Fault; EFZ, Ezinepazarı Fault Zone; KTF, Kefalonia Transform Fault; MAF, Movri-Amaliada Fault; MOF, Malatya-Ovactık Fault; NAT, North Anatolian Trough; TIP, Turkish–Iranian Plateau.
Barbot, S. & Weiss, J.R. (2021), Geophysical Journal International, 226, 422
Segments of the East Anatolian Fault derived from the historical earthquakes and geology along the fault. The pink and orange stars indicate the locations of the February 6, 2023, magnitude 7.8 and 7.5 earthquake epicenters respectively. The magnitude 7.8 earthquake ruptured the East Anatolian Fault , while the magnitude 7.5 earthquake occurred along the Sürgü fault, which branches to the west from the East Anatolian Fault. The red braces indicate the extent of slip along the named historical earthquakes. Note that in the map, north is to the top right. FC: Fault Complex; RB: Releasing Bend; RtB: Restraining Bend; DRrB: Double Restraining Bend; PB: Paired Bend; Ulv: Uluova; NAF: North Anatolian Fault.
Guvercin, S.E., et al. (2022), Geophysical Journal International 230, 50
The history of major earthquakes along the North Anatolian Fault (colored purple and yellow) showing how the earthquakes have migrated to the west. The color shading shows surface movement, with blue representing east-to-west movement and red west-to-east.
Hussain, E., et al. (2018), Nature Communications 9, 1392
Interferometric Satellite Radar Imagery (InSAR)
InSAR images are interferograms obtained by subtracting a synthetic aperture radar image of the Earth’s surface from a second such image captured during a subsequent orbit of a radar satellite. The images are colored to represent the phase difference between the two images. The closer the fringes, the greater the deformation.
The InSAR image of the earthquake region described by Romain Jolivet in the podcast. It is an Interferogram of the earthquake region generated by subtracting radar images captured on successive passes of the Sentinel 1 satellite on January 29 and February 10, 2023. The earthquakes occurred on February 6. The satellite captures a 250-km-wide swath of the Earth’s surface and revisits the same location every 12 days. The image is centered on the East Anatolian Fault. The interferogram fringes appear to converge on the fault at points about 300 km apart, indicating the approximate length of the surface rupture. As explained in the podcast, deformations cannot be observed near the fault where the deformation was large and coherence was lost. The rate at which the deformation decreases (indicated by fringe spacing increases) is a measure of the extent of the slip at depth, with slip extending to greater depths causing deformation to extend farther away from the fault. The circles indicate the location of earthquakes, the largest two white ones being the magnitude 7.8 and 7.5 earthquakes of February 6.
Sentinel 1 (ESA/Copernicus) InSAR processing by ISCE