We present a new catalog for the East Anatolian Fault Zone, covering from 2017 until February 2023—just before the M 7.8 and M 7.6 earthquakes that struck Türkiye, causing ~50,000 casualties. With unprecedented detail, the catalog reveals how seismicity evolved in the region where the major rupture began.

We find that eight months before the M 7.8 earthquake, small earthquakes began to concentrate around a minor fault near the eventual rupture initiation point. These events shifted from being mostly isolated to forming tightly packed clusters.

We interpret this clustering as a signal of a late-stage preparatory process, similar to patterns observed in Southern California. This process may have enabled the rupture to jump from the minor fault to the EAFZ. Finally, we examine the structure of the most prominent clusters to better understand how earthquakes interact within them, drawing connections to behaviors observed in laboratory experiments.