A Study of Lg Coda Attenuation in North China— the Measurement of Lg Coda Q

AbstractBy using Lg coda time series with high signal‐to‐noise ratio from North China telemetry and digital seismic network during the period from 1989 to 1998 (ML ≥ 3.0), the spatial distribution of Lg coda Q(Q = Q0fn)is obtained with the stacked spectral ratio method through pretreatments of filtering and eliminating background noise. The results show that there is a significant lateral heterogeneity on Lg coda Q distribution in North China, which is approximately consistent with the velocity distribution in the crust of the region, and is related with the surface geological features. High Q0 values appear on propagating paths located in uplift areas, and low Q0 values in depression areas. Middle Q0 values exist on propagating paths between uplift and depression areas. These indicate that the crustal structure beneath the North China region has no abrupt change which can destroy seismic wave‐guide. The Lg coda Q0 values reflects basically intrinsic visoelastic attenuation of the crustal media.