High resolution regional seismic attenuation tomography in eastern Tibetan Plateau and adjacent regions

Abstract

The Q of regional seismic phases Lg and Pg within the crust is assumed as a proxy for crustal Qβ and Qα, which is used as a constraint of crustal rheology. We measure regional‐phase Q of the eastern Tibetan Plateau and adjacent areas. This method eliminates contributions from source and site responses and is an improvement on the Two‐Station Method (TSM). We have generated tomographic images of crustal attenuation anomalies with resolution as high as 1°. In general we observe low Q in the northernmost portions of the Tibetan Plateau and high Q in the more tectonically stable regions such as the interior of the Qaidam basin. The calculated site responses appear to correlate with topography or sediment thickness. Furthermore the relationship between earthquake magnitudes and calculated source terms suggest that the RTM method effectively removes the source response and may be used as an alternative to source magnitude.