REELFOOT RIFT AND NEW MADRID SEISMIC ZONE EARTHSCOPE USARRAY TARGET

The northeastern end of the Cambrian Reelfoot rift is home to the New Madrid seismic zone. However, the detailed structure of the rift, and in particular its full seismic potential is poorly constrained. Recent research indicates that the entire Reelfoot rift has undergone Quaternary right lateral shear, but only the northeastern end of the rift is currently seismically active. Fundamental questions that remain to be answered include, 1) are currently quiet Reelfoot rift faults capable of generating earthquakes, 2) is the Reelfoot thrust fault an inverted normal fault that bounds the Reelfoot rift's northern margin, 3) is the seismogenic New Madrid North fault a northwestern rift margin fault, 4) is the Reelfoot rift continuous with the Rough Creek graben, 5) do the Proterozoic Central Plains Orogen faults in the Missouri and Arkansas Ozarks pass under and displace the overlying Granite Rhyolite Province strata to divide the Reelfoot rift into sub-basins, 6) what is the full extent and geometry of the mafic rift pillow that underlies the Reelfoot rift at the base of the crust, and 7) what are the geometries of the Phanerozoic plutons in the Reelfoot rift?

On a more regional scale the Mississippi Embayment formed due to passage over the Bermuda hotspot during the Cretaceous. Can this hotspot track be mapped by tomography and is there a relationship between the track and today's New Madrid seismicity? Can we image the Reelfoot rift at depth thereby providing insight into intraplate rifts globally? These and many more fundamental questions can be addressed in the Earthscope USArray program and justifies including the Reelfoot rift and northern Mississippi Embayment as part of a continent wide GeoSwath.