The 2020 Mw 6.8 Elazığ (Turkey) Earthquake Reveals Rupture Behavior of the East Anatolian Fault

• Published in: Geophysical research letters 2020-07, Vol.47 (13), p.n/a
• Main Authors: Pousse‐Beltran, Léa, Nissen, Edwin, Bergman, Eric A., Cambaz, Musavver Didem, Gaudreau, Élyse, Karasözen, Ezgi, Tan, Fengzhou
• Format: Article
• Language: English
• Subjects: Deformation; earthquake; Earthquakes; Fault lines; Faults; Geodesy; Geodetics; Geological faults; Geological hazards; Hazard assessment; Nucleation; Offsets; Rupture; Rupturing; Satellites; Seismic activity; Seismic hazard; Seismology; Slip; Structural models; Turkey
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2020GL088136

The 2020 Mw 6.8 Elazığ earthquake was the largest along the East Anatolian Fault (EAF) in over a century, providing valuable insights into its rupture behavior. We use satellite geodesy and seismology to detail the mainshock rupture, postseismic deformation, and aftershocks. The mainshock propagated mostly westward at ∼2 km/s from a nucleation point on an abrupt ∼10° fault bend. Only one end of the rupture corresponds to an established EAF segment boundary, and the earthquake may have propagated into the slip zone of the 1874 M ∼ 7.1 Gölcuk Gölu earthquake. It exhibits a pronounced (∼80%) shallow slip deficit, only a small proportion of which is recovered by early aseismic afterslip. The slow rupture velocity, shallow slip deficit, and minimal afterslip are characteristic of earthquakes hosted by faults of low‐to‐intermediate structural maturity, indicating that faults continue to evolve in important ways even as they accrue cumulative offsets of tens of kilometers. Plain Language Summary We investigate the 2020 Mw 6.8 Elazığ (Turkey) earthquake, the largest along the East Anatolian Fault (EAF) in over a century. Anatolian faults are emblematic within the earthquake science community, but most attention has focused on the North Anatolian fault which ruptured repeatedly during the twentieth century, and relatively little is known about the EAF. We use satellite geodesy and seismology to map fault motions during the earthquake, after the earthquake, and in its aftershock sequence. Documenting relations between this earthquake, previous earthquakes, and early postseismic deformation is pivotal to gain a better understanding in what drives rupture behavior. Our results show that previous structural models of the EAF were only partially successful in predicting the end points of the 2020 rupture and that many aspects of this earthquake are characteristic of structurally immature faults. These results are important for seismic hazard assessment in this region. Key Points The mainshock propagated mostly westward from a nucleation point on an abrupt ∼10° fault bend Only one rupture termination corresponds to an established EAF segment boundary, and the rupture may partially overlap with an 1874 earthquake The mainshock exhibits a pronounced shallow slip deficit that is not fully recovered through early shallow afterslip