CodaNorm: A software package for the body-wave attenuation calculation by the coda-normalization method

The software package CodaNorm was applied for the estimation of the attenuation of the body P- and S-waves in the area of the South and Central Baikal (Baikal rift system, Southern Siberia, Russia) using 185 regional earthquakes with magnitude Ml=2-5. The calculations were carried out for eight traces crossing the rift system in different directions and for the frequency range from 0.5 to 16 Hz. In the low frequency area the coincidence of the values of the seismic quality factor for P- and S-waves (QP and QS, respectively) is observed while for the high frequencies (8-16 Hz) the ratio between quality factors is QS≈1.7QP. Such difference is the evidence of different absorption of longitudinal and transverse waves by geological medium. The comparison of the attenuation parameters for different azimuthal traces showed that higher attenuation is observed for the traces crossing the rift system in normal direction to the main tectonic structures. This fact may reflects the differences between the local elastic properties of the crust of the Baikal rift system and the high heterogeneity of the medium.