This study investigates seismic body-wave attenuation in the Biga Peninsula, northwestern Türkiye, focusing on the quality factors of P waves (Qp) and S waves (Qs) across the Ganos Fault Zone (GFZ), Çan-Biga Fault Zone (CBFZ) and Ayvac\(\mathrm{\imath}\)k Fault Zone (AFZ). We analysed 1,714 local earthquakes recorded by 12 seismic stations from 2010 to 2019 using the Coda Normalization Method (CNM) to determine frequency-dependent attenuation for 10 central frequencies (between 1.5 and 18 Hz). Each fault zone exhibits distinct attenuation characteristics, which are influenced by its unique geological and tectonic structure. The Ganos Fault Zone, part of the northern branch of the North Anatolian Fault, represents power-law equations of Q\(_{p}\)(f)=12.2f\(^{1.15\ }\)and Q\(_{s}\)(f)=20.7f\(^{1.24}\), with an average Q\(_{s}\)/Q\(_{p}\) ratio of 2.02, consistent with the thick, heterogeneous Neogene sediments in the Thrace Basin that increase absorption and scattering. The strike-slip Çan-Biga Fault Zone is defined by functions of Q\(_{p}\)(f)=6.7f\(^{1.40}\), Q\(_{s}\)(f)=19.3f\(^{1.36}\), and an average Q\(_{s}\)/Q\(_{p}\) ratio of 2.58, indicating significant scattering and fluid-related attenuation in its fractured structure. In contrast, the extensional Ayvac\(\mathrm{\imath}\)k Fault Zone has Qp(f) = 34.7f\(^{1.33\ }\)and Qs(f) = 8.4f\(^{1.15}\), with the lowest Qs/Qp ratio (\(\mathrm{\approx}\)1.63), indicating efficient P-wave propagation but strong S-wave attenuation due to geothermal activity, hydrothermal alteration, and young volcanic units. The findings highlight that fault type and lithology are the primary factors controlling seismic attenuation in the Biga Peninsula. The differences between strike-slip and extensional fault zones also offer insights into the effects of scattering, fluid content, and crustal heterogeneity on attenuation. These region-specific Qp(f) and Qs(f) relations provide essential input functions to many seismological investigations, such as ground motion simulation, focal mechanism calculation, spectral source characterization, etc. and will improve seismic hazard assessments in NW Türkiye.
