"Passive Source Seismic Imaging of the Continuous US and the Southern Margin"

November 1, 2019 9:00 AM
Robert Porritt

Robert Porritt
Research Engineering/Scientist Associate V
Institute for Geophysics, The University of Texas at Austin

The USArray has facilitated a revolution in passive source seismic imaging and observations of seismicity. Here we present multi-scale imaging results for the continuous US utilizing multiple seismic imaging methods. For the broadest, continent-wide scale, we jointly invert body-wave delay times with Rayleigh and Love surface waves in a data-adaptive, radially anisotropic global model with fine resolution under the USArray. From this model, we are able to track the subduction of the Farallon slab, along with assessing the variations in the structure of the lithosphere. This is perhaps most notable along the Ouachita-Marathon Front, where the thick cratonic lithosphere is adjacent to significantly thinner lithosphere. Zooming into this region using data from TexNet and a joint inversion of ambient seismic noise and receiver functions, we can start to assess the thinning of the crust and mantle lithosphere across this transition and investigate the source region of induced seismicity. Our model suggests some earthquakes in southeastern Texas are occurring near the top of the basement and that there is a correlation between observed seismicity and uplifted middle crust, such as the San Marcos Arch.