These investigators, along with graduate and undergraduate students, are installing 83 broadband seismic stations from the EarthScope Flexible Array pool to explore the deep structure of the Mid-Continent Rift System (MCRS). The MCRS is the fossil remnant of an extensive rifting event that failed to split North America during the Middle-Proterozoic era. This event left a large volume of dense basalts and associated strong geophysical anomalies. By imaging the deep structure beneath the rift, this seismic experiment investigates how such rifts form and then die, rather than developing into oceanic spreading centers. The seismic stations are located around, across, and along the failed rift, from the Minnesota-Iowa border into Canada by Lake Superior. Imaging the deep seismic structure of a central part of the MCRS will be undertaken with receiver function migration, ambient noise analysis, teleseismic surface wave dispersion analysis, regional S- and surface wave-train fitting, teleseismic arrival time tomography, re-analysis of existing seismic reflection & refraction data, and SKS-splitting analysis. These analyses are combined into a multi-resolution, three-dimensional image of the isotropic and anisotropic structure of the crust and mantle beneath the MCRS and its surroundings. Results of these analyses will illuminate the role of the mantle in the rifting process and its initiation and cessation. The results will also enhance our understanding of mid-continental earthquakes. This research project employs at least three graduate students, also involves undergraduate students, and fosters collaboration between researchers from Canada and the USA.
