A Stochastic View of the 2020 Elazig Mw 6.8 Earthquake (Turkey)

Until the M-w 6.8 Elazig earthquake ruptured the central portion of the East Anatolian Fault (EAF, Turkey) on January 24, 2020, the region had only experienced moderate magnitude (M-w < 6.2) earthquakes over the last century. We use geodetic data to constrain a model of subsurface fault slip. We adopt an unregularized Bayesian sampling approach relying solely on physically justifiable prior information and account for uncertainties in both the assumed elastic structure and fault geometry. The rupture of the Elazig earthquake was mostly unilateral, with two primary disconnected regions of slip. This rupture pattern may be controlled by structural complexity. Both the Elazig and 2010 M-w 6.1 Kovancilar events ruptured portions of the central EAF that are believed to be coupled during interseismic periods, and the Palu segment is the last portion of the EAF showing a large fault slip deficit which has not yet ruptured in the last 145 years. Plain Language Summary The Elazig earthquake ruptured the central portion of the East Anatolian Fault (EAF), a major strike-slip fault in eastern Turkey, on January 24, 2020. Before this event, the region had only experienced moderate magnitude earthquakes over the last century. We aim at understanding the rupture of this earthquake, and how it relates to the historical ruptures of the EAF. To do so, we use measurements of displacement at the surface to image the subsurface slip on the fault that occurred during the earthquake. As the characteristics of the crust are poorly known, we make realistic assumptions on the fault geometry and Earth structure, and build on novel approaches to account for the possible biases of our assumptions and to characterize the uncertainties of the imaged slip. We suggest that the Elazig earthquake rupture may be controlled by structural complexity of the fault, and that two main regions of slip surround a fault bend acting as a barrier to rupture propagation. We also suggest that the fault segment located between Lake Hazar and the city of Palu is the last portion of the central EAF, showing a large deficit of the fault slip, which has not yet ruptured in the last 145 years.

Automated summary

The M-w 6.8 Elazig earthquake in Turkey on January 24, 2020 ruptured the central portion of the East Anatolian Fault, which had previously only experienced moderate magnitude earthquakes. Using geodetic data, a model of subsurface fault slip was constrained, showing a primarily unilateral rupture pattern controlled by structural complexity. The earthquake events in the region are believed to be linked to historical ruptures of the EAF, indicating the potential for future seismic activity.