A Comparison of Attenuation of the Lithosphere in Continental Regions

Using a multi-phase regional amplitude tomography method (Pasyanos et al., 2009 BSSA), we have developed attenuation models (Qp and Qs) of the crust and upper mantle for a broad frequency band ranging from 0.5 - 10 Hz. Since the models are constructed using the amplitudes of regional phases (Pn, Pg, Sn, Lg), the models cover mostly continental regions that reside within regional distances (~16 degrees) of ambient seismicity. In all regions, we find that the crust and upper mantle attenuation maps correlate well with tectonic structure, with active regions (orogenic zones, ridges, etc.) having lower Q values (high attenuation) and more stable cratonic regions having higher Q values (low attenuation). Here, we will conduct a comparison of global attenuation results, primarily focused on the continents. Since attenuation is known to be very sensitive to temperature, we will compare our attenuation results of the lithosphere to proxies for temperature, such as surface heat flow models, lithospheric thickness, and the recency of thermo-tectonic activity. In addition, we will examine whether there are significant differences among cratons, between shields and platforms, and between regions of adjacent ocean and continental crust.