Attenuation measurements on shallow seismic refraction data in the Kocaeli region, Turkey: Fid-Bau Portal

Attenuation measurements on shallow seismic refraction data in the Kocaeli region, Turkey

Cengiz Kurtuluş / Fadime Sertçelik

Attenuation of P-waves (Q_p₎ in different geologic units in the Kocaeli region, NW of Turkey, was determined using both the pulse-broadening and the spectral amplitude ratio techniques. With that aim, shallow seismic refraction data were conducted at total 97 points at the Sirintepe, Akveren, Izmit, Korucu, Arslanbey, Sopalı, Peksimet and the Çınarlıdere formation sites, which are generally in dry states located in the vicinity of the North Anatolia Fault within the Kocaeli segment. The Q_p values determined from both techniques were correlated. The wide variation of the computed Q_p values indicated that the spectral technique can found to be generally slightly better than the pulse-broadening method. In addition to these studies, the dynamic elastic properties were figured out using P and velocities determined from seismic refraction studies, and the natural water content and density of the subsoil layers were determined from the soil samples collected from total 36 boreholes drilled in the formations to observe their variation with Q_p values. The dynamic elastic properties determined using P- and S-wave velocities in empirical equations were correlated with the quality factors. Generally, the physical parameters did not represent any linear relations with the quality factors which demonstrated that the attenuation characteristics of seismic waves cannot be used to derive dynamic elastic parameters of the subsurface sediments.