UCLA

The 2023 Türkiye/Syria earthquake sequence includes the February 6 M7.8 mainshock followed approximately nine hours later by a M7.7 aftershock, and many smaller aftershocks including a M6.8 and M6.3 on February 6 and 20, respectively. These events occurred in a region near the plate boundary of the East Anatolian Fault, in the proximity of which numerous ground motion recordings sites had been installed north of the Türkiye/Syria border. As a result, the events were well recorded both near the fault and at rupture distances up to 570 km. We describe the available recordings and component-specific data processing performed with the aim of optimizing usable bandwidth. The resulting database includes 310, 351, 291, and 229 usable three-component recordings from the M7.8, M7.7, M6.8, and M6.3 events, respectively. We also present source, path, and site metadata that was compiled according to uniform protocols. Comparisons to a global ground motion model (GMM) for active tectonic regions and a local, Türkiye-specific model demonstrate the existence of complex path effects that result in relatively poor fits between the GMMs and observed data at large distances (generally RJB > 200 km). Under-predictions at some stations may be influenced by directivity and/or basin effects that affect the ground motions but that are not accounted for directly in the GMMs. We also present analysis of spatial variability of peak ground acceleration for the M7.8 mainshock. A residual map produced from this analysis demonstrates that the global GMM over-predicts on the Anatolian block and under-predicts on the Arabian block, further supporting the existence of complex attenuation features in the region.