Complex rupture dynamics on an immature fault during the 2020 Mw 6.8 Elazığ earthquake, Turkey

Abstract

Physical laws governing friction on shallow faults in the Earth and spatial heterogeneity of parameters are critical to our understanding of earthquake physics and the assessment of earthquake hazards. Here we use a laboratory-derived fault-friction law and high-quality strong-motion seismic recordings of the 2020 Elazığ earthquake, Turkey, to reveal the complex rupture dynamics. We discover an initial Mw 5.8 rupture stage and explain how cascading behavior of the event, involving at least three episodes, each of M > 6, caused it to evolve into a large earthquake, contrarily to other M5+ events on this part of the East Anatolian Fault. Although the dynamic stress transfer during the rupture did not overcome the strength of the uppermost ~5 kilometers, surface ruptures during future earthquakes cannot be ruled out. We foresee that future, routine dynamic inversions will improve understanding of earthquake rupture parameters, an essential component of modern, physics-based earthquake hazard assessment.

From Interseismic Deformation With Near‐Repeating Earthquakes to Co‐Seismic Rupture: A Unified View of the 2020 Mw6.8 Sivrice (Elazığ) Eastern Turkey Earthquake

“…The existence of the foreshock and the actual location of the mainshock are also pointed out by Gallovič et al. (2020), and their epicenter for the mainshock and estimated magnitude are similar to this study.…”

“…We estimated the magnitude of the foreshock as M ∼ 5.4 from the azimuthal average of P wave amplitude ratios of the foreshock and mainshock. The existence of the foreshock and the actual location of the mainshock are also pointed out by Gallovič et al (2020), and their epicenter for the mainshock and estimated magnitude are similar to this study.…”

“…Our inferred rupture velocity is slightly higher than previously reported value of 2.2 km/s by Gallovič et al. (2020). The rupture velocity is still significantly slower than the 1999 M w 7.4 Izmit, and M w 7.1 Düzce earthquakes along NAF, which propagated with speeds higher than the S‐wave speed (Bouchon et al., 2001; Konca et al., 2010).…”

“…This led Gallovič et al. (2020) to interpret the EAF as an immature fault, leading to a slower rupture velocity and lack of surface slip. The heterogeneous stress with patches of high and low prestress, and barriers either due to fault complexity or interseismic behavior, led to a partial rupture of the segment.…”

Early Stage and Main Ruptures of the 2015 Mw8.3 Illapel, Chile, Megathrust Earthquake: Kinematic Elliptical Inversions and Dynamic Rupture Simulations

“…More recently, Gallovič et al. (2020) obtained for the 2020 M6.8 Elaziğ (Turkey) earthquake 1 m and a total fracture energy of 3.3 × 10 15 J. This is close to our scaling assumption (e.g., Aochi & Twardzik, 2020).…”