Apparent Attenuation Beneath the United States and its Correlation with Lithospheric Provinces

Abstract:

We map apparent attenuation beneath the continental United States through an analysis of ~16 deep-focus teleseismic events recorded by the USArray Transportable Array. For each event, we stack the best quality recordings to generate a source estimate and then apply an attenuation operator to the source estimate using a range of t* values to fit the record at each station. The regional attenuation pattern is extracted from the ensemble of observations using a regularized inversion scheme. Preliminary results from the analysis of four events show good correlation with tectonic boundaries. The lowest apparent attenuation occurs in the upper Midwest, and corresponds to the Superior Craton; while high apparent attenuation dominates outside the cratonic continent as defined by the Rocky Mountain, Ouachita and Appalachian fronts. Our results indicate that different lithospheric provinces have distinct attenuation signatures that are consistent with expectations.