3D Analysis of Scattering Attenuation Before and After the February 6, 2023, Earthquake Doublet in Türkiye

On February 6th, 2023, an earthquake of Mw 7.8, known as the Kahramanmaraş earthquake, struck between southern Turkey and northern Syria. The strike-slip event ruptured multiple southwestern segments of the East Anatolian Fault System (EAFS). It was followed by a severe series of aftershocks, as the Mw 7.6 Elbistan earthquake, occurred just nine hours from the Kahramanmaraş event, rupturing an east-west trending fault near the main EAFS. The Mw 6.4 Antakya aftershock occurred along a bifurcation of the EAFS.

Seismic attenuation is a powerful tool to look at variations in the crustal properties, being strongly controlled by structural irregularity and heterogeneities: fractures, temperature, and pressure variations can cause an increase or a decrease in the amplitude of seismic wave amplitude. Hence, seismic attenuation imagining can provide us with information about the areas with a variation in fracturing or other changes in the crust (Gabrielli et al., 2022; 2023; 2024).

This work aims to present an initial 3D imaging of seismic wave scattering variations before and after the February 6th earthquakes, examining their spatial and temporal changes at different frequency bands. To achieve this, we utilized distinct datasets: the first covers the period before the sequence (pre-sequence phase, January 2020 - February 5, 2023), while the second begins with the February 6 event and extends through May 2023 (sequence phase). The datasets are composed of ~48000 waveforms for the pre-sequence and ~238000 for the sequence, recorded by 64 stations, ensuring a good coverage for our analysis in the examined area. 

We calculated the peak-delay parameter, a proxy of seismic scattering, and mapped using a regionalization approach. The preliminary results show a difference between the pre-sequence and the sequence phase, with increased scattering between the  EAF main branch and the Sürgü-Çardak Fault (to the northwest). Between the EAF and the North Anatolian Fault/Bingol area, we record a constant high scattering.