The preparatory process of the 2023 Mw 7.8 Türkiye earthquake.

To verify the existence of a preparatory process for the 6 February 2023, Mw 7.8 Kahramanmaraş earthquake, southern Türkiye, we analyze the temporal evolution of seismic catalog information for ~ 7500 earthquakes with magnitudes M ≥ 1.5, which occurred along the main segments of the East Anatolian Fault (EAF) since 2014. We find the EAF fault segments showing different temporal patterns in the proportion of nonclustered seismicity, which we interpret as temporal variation of coupling. We also study the evolution of the b-value, fractal dimension and energy rate. These seismic features show for the Amanos and Pazarcık fault segments a long-term trend during the period 2020-2022 that might correspond to a quiescence phase. The latter is followed by a change in earthquakes clustering and characteristics that starts about eight months before the Mw 7.8 Kahramanmaraş event. Our observations confirm the existence of a long-lasting preparatory phase for the 2023, Mw 7.8 Kahramanmaraş earthquake and can stimulate new investigations on the East Anatolian Fault mechanic. Intercepting when a fault starts deviating from its steady behavior, might be the key for identifying the preparatory phase of large earthquakes and mitigate seismic risk.