The Preparatory Process of the 2023 Mw 7.8 Turkey Earthquake

Abstract On 9 February 2023, Southern Turkey was struck by a magnitude 7.8 earthquake. Especially during major events, seismologists are confronted with the inability to predict earthquakes. Indeed, how, when, and where large earthquakes are generated remain fundamental unsolved scientific questions. We analyze the spatio-temporal evolution of thousands of small magnitude earthquakes for the two years that preceded the mainshock. We find that patterns in seismic spatial distribution and energy released per event are clues of a ten-month lasting preparatory process. Our results suggest the existence of a progressive localization of seismic events and stress over a large area of the fault segment which released the higher slip during the earthquake. When the mainshock has nucleated, it might have found the unfortunate best conditions to grow. Intercepting when a fault system starts deviating from its steady behavior might be the key for identifying the preparatory phase of large earthquakes.