An analysis of directivity pulses using empirical data and dynamic rupture simulations of the 2023 Kahramanmaras earthquake doublet

Near-field earthquake ground motions characterized by strong velocity pulses can cause extensive damage to buildings and structures. Such pulses were identified during the Mw 7.8 and Mw 7.5 earthquake doublet of the 2023 Turkey seismic sequence, potentially contributing to the extensive damage it caused. Therefore, a better understanding and characterization of pulse properties (e.g. period and amplitude) and their underlying physical factors are crucial for earthquake-resistant design. In this study, we characterize the velocity pulses reported in observed records and synthetic waveforms generated by a three-dimensional (3D) dynamic rupture simulation of the Mw 7.8 event. We observed significant variability in the pulse properties of the observed records in near-fault regions, particularly regarding their orientations. This variability was not fully captured by the dynamic rupture simulation. Our results indicate that directivity effects are not the only factors influencing pulse characteristics in this earthquake doublet. While site effects (e.g. basin effects) may influence pulse characteristics at some stations, local heterogeneities in slip amplitude, orientations, and fault geometries can be critical in generating or influencing pulse properties in this earthquake doublet.