SHEAR-WAVE VELOCITY STRUCTURE OF THE CRUST AND UPPER MANTLE IN EASTERN NORTH AMERICA FROM FULL-WAVE AMBIENT NOISE TOMOGRAPHIC IMAGING

Eastern North America provides a superb opportunity to advance our understanding of continental accretion and lithospheric evolution through geologic time. An important characteristic of the eastern North American passive margin is the observed along-strike variation in a wide variety of properties and processes. However, the causes, effects, and relationships among the various along-strike gradients are not well understood. In this study, the crust and upper mantle seismic structure of eastern North America is imaged with full-wave propagation simulation and ambient noise tomography. To retrieve Rayleigh-wave Empirical Green’s Functions between station pairs, the vertical component of continuous seismic data, recorded from 1995 to present by a total of 1031 seismic stations, are processed. The combined data set includes sites from EarthScope Transportable Array, Canadian and US national/state networks, LDEO and New England networks, the ENAM Community Seismic Experiment, and a number of portable deployments. Central and Eastern US network (CEUSN) retained many of the TA sites in the region. The frequency-time waveform normalization method improves the quality of surface waves extracted from ambient seismic noise. In this study we include Rayleigh waves at a wide period range of 7-300 seconds, which approximately corresponds to a depth range of 10-300 km. The ray path coverage is excellent, allowing us to achieve a fine-resolution shear-wave velocity model from the uppermost crust through the mantle lithosphere down to the upper mantle. The checkerboard resolution tests of seismic tomographic imaging show that we are able to resolve the crustal structure at a horizontal scale of 30-40 km and the upper mantle structure at a horizontal scale of 50-75 km. The waveform cross-correlations between land-land and land-ocean station pairs along the eastern North American margin provide preliminary resolution of seismic structures immediately offshore near the coast in eastern North America. A shear-wave velocity model from the crust down to mantle lithosphere will be presented during the meeting.