Southern Türkiye faced widespread catastrophic destruction by two devastating earthquakes on the same day. As the earthquakes occurred at 04:17 (M _w = 7.7, Pazarcık, Kahramanmaraş) and 12:30 (M _w = 7.6, Elbistan, Kahramanmaraş) on 6 February 2023, neighbouring active fault systems were broken in succession between the Hatay and Malatya provinces in the region. The first earthquake, one of the largest earthquakes in this region during the last century, caused major fatalities and widespread damage to infrastructure and buildings, and produced large-scale seismo-gravitational surface deformation such as landslides, lateral spreading, liquefaction and extensional cracks. Here, we present the surface rupture geometry and coseismic displacement characteristics of the fault systems, determined by field observations immediately after the 6 February 2023 Pazarcık (Kahramanmaraş, Türkiye) earthquake (M _w = 7.7). Preliminary results show that the total rupture length ( L _max ) is 270 ± 10 km on the Karasu, Pazarcık and Erkenek segments of the East Anatolian Fault Zone. Left-lateral strike-slip faulting developed with a maximum horizontal displacement ( D _max ) of 7.30 m and an average displacement ( D _avg ) of 3.00 m. Although the surface rupture generally exhibits a narrow deformation zone width of 2–5 m, this expands to 50 m in some sections of the faults. The implications for rupture dynamics suggest that fracture development started on a secondary fault (Narlı Fault), transferred to the main fault and triggered the breaking of asperities on the Pazarcık segment, which exhibits a long period of accumulation of stress, to initiate the major rupturing. Supplementary material: Figures S1–S12 with details on coseismic displacement are available at https://doi.org/10.6084/m9.figshare.c.6487245

New ages and strain analysis of syntectonic calcite from the west-central part of the North Anatolian fault zone (NAFZ; northern Turkey) shed light on the debate over the origin and reactivation behavior of this major active fault system. Contrasting views suggest that the west-central part of the NAFZ was already active during the mid-Eocene, mid-Miocene, or early Pliocene. The deformation style is also controversial: early stages of activity are associated with strike-slip, thrust, or normal faulting. Strike-slip deformation of the NAFZ marks the onset of tectonic escape of the Anatolian block westwards and is therefore a key player in tectonic reconstructions. We sampled syntectonic calcite from polished fault surfaces with horizontal slickenlines at four key sites along a 190-km-long sector of the NAFZ. All sites still show active faulting during the Holocene. Combined U-Pb ages (laser ablation–multicollector–inductively coupled plasma–mass spectrometry) and strain analyses of mechanically twinned calcite indicate that the west-central part of the NAFZ was associated with an extensional normal fault system at 42 Ma and reactivated as a dextral strike-slip fault at least 11 m.y. ago. The results indicate that the NAFZ evolved through the reactivation of major preexisting fault structures rather than by a gradual east (13 Ma) to west (5 Ma) propagation. The onset of westward translation of the Anatolian block occurred at least 11 m.y. ago, possibly as a result of the Miocene collision between the Arabian plate and Anatolian block.