Unit Affiliation: Seismology, Geology and Tectonophysics, Lamont-Doherty Earth Observatory (LDEO)
The project will use data from the 10-year deployment of the seismic stations in the USArray Transportable Array across the lower 48 states to map seismological properties of the top 100 km of the crust and shallow mantle beneath the continent. The focus of the project is a comprehensive analysis of seismic surface waves using traditional and modern methods, including the analysis of ambient seismic noise, which are seismic waves caused by human activity, ocean waves, and atmospheric phenomena such as wind. The project will generate high-resolution maps of different properties of the rocks in the crust and mantle that will facilitate continent-wide interpretation of the structure and tectonic evolution of North America. The seismic data collected by nearly 2000 sensors distributed across the continent will be used to determine (1) maps of short-period (5-40 sec) Love and Rayleigh wave speed using inter-station cross correlation of seismic noise; (2) maps of longer-period (25-125 sec) Love and Rayleigh wave speed using two-station and mini-array techniques; and (3) maps of local elastic Rayleigh wave amplification at longer periods using a differential-amplitude technique. Quantitative comparisons of the data with model-based predictions will be used to demonstrate the consistency between results of different researchers, and identify differences that motivate further investigation.