Source parameters and scaling relation of the Baikal rift's earthquakes

Abstract

Source parameters (the seismic moment M 0, the moment magnitude Mw, the source dimension [radius] r, the displacement amplitude D, and the stress drop Δσ) of the Baikal rift system's earthquakes were obtained by analyzing short-period records of S-waves of 150 local events with magnitude M L=3.1–4.7. For the source parameters calculation, Brune's model was used. To estimate the source spectrum, the local site corrections, path effects (the geometrical spreading and the attenuation), and source pattern were considered. The local site effects for all the seismic stations were obtained by Nakamura's method using ambient noise. The comparison between the seismic moment M 0 and the local magnitude M L relations for the Baikal rift system and other rift zones (such as the rifts of Greece, the North Sea, and Basin and Range Province) shows a satisfactory agreement whereas a significant difference is observed for the scaling relations “M 0 – M L” for rift zones and other tectonic settings (such as the transform fault, the Vrancea zone, the compression zones). This evinces the existing general pattern of the lithosphere's destruction and the seismicity in the crust extension settings.