SCIENTIFIC RATIONALE FOR A GREATLY DENSIFIED PERMANENT SEISMIC NETWORK IN THE CENTRAL PLAINS UTILIZING USArray

The Central Plains (CP) area of the conterminous U.S. is characterized by a diverse amalgamation of tectonic features developed over the past 2 billion years. Boundaries between three major Precambrian terranes and one of the largest continental rift systems on Earth (the Midcontinent Rift) are located in this area. Preliminary geophysical studies suggest that the mantle transition between the Cenozoic Cordilleran and the ’stable’ North American craton lies within the western part of this area. In addition, some of the greatest historical earthquakes in the conterminous United States have occurred in the New Madrid Seismic Zone in the southeastern CP. Therefore, detailed geoscientific studies of the CP will significantly improve our understanding of: (1) the growth, modification, and destruction of continental lithosphere; (2) the nature of the active-to-stable transitional area in the mantle; and (3) the formation mechanism of intra-continent earthquakes. However, the understanding of basement structure in the CP is rudimentary because it is obscured by sedimentary cover, and is thus greatly dependent on a state of the art permanent broadband seismic network. The lack of damaging historic earthquakes in most of the CP has resulted in fewer seismological research efforts relative to the western US. Over the past several decades, seismology has evolved into a much broader branch of geoscience that examines not only earthquakes, but also the structure and dynamics of the Earth's deep interior using data from permanent stations collected over decades. The detectability of the current sparse seismic network in the area can be greatly improved by converting some of the USArray stations into permanent ones. The greatly-densified permanent seismic network will dramatically improve our capability for studying the velocity, anisotropy, and layered structures of the Earth's crust, mantle and core, detecting small earthquakes, assessing seismic risks, and providing effective education and outreach to the general public. To facilitate such an effort, CPEP (Central Plains Earthscope Partnership) was established in 2007. Currently CPEP involves about 60 geoscientists from four CP states (NE, IA, KS, MO). Detailed information about CPEP can be found at http://seismo.device.mst.edu/cpep