SPREE stations sense soil-dependent response to atmosphere
Seismic stations of the Superior Province Rifting Earthscope Experiment (SPREE) were installed in shallow hand-dug vaults in Minnesota, Wisconsin, and Ontario around the Mid-continent Rift. Because of their shallow burial in soft soil, SPREE stations were able to sense the tilting of the Earth’s surface caused by fluctuations in atmospheric pressure.
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Igneous rock layers above and below the continental crust of the MCR
The Mid-continent Rift is distinguished by voluminous one-billion-year-old lava flows. Layer boundaries in the Mid-continent’s Rift’s crust scattered some of the distant earthquakes’ seismic wave energy in ways that the SPREE stations could record perceptibly for more than one hundred earthquakes. Our analysis of these scattered waves reveals
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A clearer look at a giant scar that underlies the American Midwest
Buried beneath the fertile flat farmland of the midwest, a huge scar gives rise to the most prominent gravity and magnetic anomalies within the old and stable core of the North America continent. The Midcontinent Rift (MCR) was the location of an episode of extension between eastern and western North America, and is now filled by a large volume of ~ 1.1 Ga old igneous rocks. Recent deployments
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One billion year-old Mid-continent Rift leaves no clues in the mantle
Seismic stations of the Superior Province Rifting Earthscope Experiment (SPREE) recorded seismic waves from distant earthquakes for two and a half years. SPREE stations were installed in Minnesota, Wisconsin, and Ontario, around the Mid-continent Rift, a feature distinguished by voluminous one billion year-old lava flows.
These lava flows along with deeper, “underplated” igneous rocks at the bottom of the crust slightly slow these seismic waves down compared to seismic waves recorded by stations away from the Mid-continent Rift. We measured the differences in arrival times
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Fabric in the crust and mantle across the Mid-Continent Rift
By analyzing earthquake recordings, we obtain information on structures within the Earth’s crust and mantle beneath the instruments. We analyzed a type of earthquake wave that travelled through the Earth’s core and is called SKS.
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