The 2023 Turkey earthquake doublet: Earthquake relocation, seismic tomography, and stress field inversion

On February 6, 2023, two earthquakes with magnitudes of M-W 7.8 and M-W 7.5 struck southeastern Turkey, causing significant casualties and economic losses. These seismic events occurred along the East Anatolian Fault Zone, a convergent boundary between the Arabian Plate and the Anatolian Subplate. In this study, we analyze the M-W 7.8 and M-W 7.5 earthquakes by comparing their aftershock relocations, tomographic images, and stress field inversions. The earthquakes were localized in the upper crust and exhibited steep dip angles. Furthermore, the aftershocks occurred either close to the boundaries of low and high P-wave velocity anomaly zones or within the low P-wave velocity anomaly zones. The East Anatolia Fault, associated with the M-W 7.8 earthquake, and the Surgu Fault, related to the M-W 7.5 earthquake, predominantly experienced shear stress. However, their western sections experienced a combination of strike-slip and tensile stresses in addition to shear stress. The ruptures of the M-W 7.8 and M-W 7.5 earthquakes appear to have bridged a seismic gap that had seen sparse seismicity over the past 200 years prior to the 2023 Turkey earthquake sequence.