Transient, accelerating slow slips drive the Preparatory Process of the 2023 Mw 7.8 Türkiye Earthquake

Abstract

On 6 February 2023, Southern Türkiye 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 aiming to highlight a preparatory process existence. We find patterns in seismic spatio-temporal distribution suggesting the existence of transient slow slip episodes accelerating in the fifteen months preceding the mainshock. Slow slip seems responsible for a progressive decoupling process in the main event nucleation area, which is highlighted by the fraction of non-clustered seismicity increase. The latter preparation phase started ~seven months before the 9 February 2023, Southern Türkiye Mw 7.8 earthquake. Our observations stimulate significant questions about East Anatolian Fault mechanics. Intercepting when a fault system starts deviating from its steady behavior, might be the key for identifying the preparatory phase of large earthquakes.