Crustal Thickness of the Eastern US from Receiver Function Analysis

Though there have been a number of controlled source seismic surveys performed within the eastern US, the depth of the Moho beneath these regions has remained somewhat ambiguous because most of the seismic rays generally turn above or undersample the Moho. Furthermore, there have been few detailed receiver function studies of crustal structure in the eastern US. In this study we present H-k stacking analysis and forward and inverse modeling of receiver functions from permanent broadband and short-period stations, as well as new stations from the TEENA network (Test Experiement for Eastern North America), which consisted of 9 broadband stations that operated in Virginia and West Virginia between 2009-2010. Overall, our crustal thickness values seem to be lower across the region, particularly in the Appalachian Piedmont province where previous estimates of crustal thickness from controlled source experiments and the EarthScope Automated Receiver Survey (EARS) have been ~ 35-40 km compared to our findings (28-33 km thick). Furthermore, forward modeling of stacked receiver functions from many Piedmont and Coastal Plain stations strongly suggests the existence of a 8-10 km layer beneath the Moho with a Vp ~7.3 km/s, which we interpret as magmatic underplate. The crustal thickness beneath the Blue Ridge Mountains and Valley and Ridge province tend to be ~ 40-50 km thick, and there appear to be abrupt changes in crustal thickness between the different physiographic provinces. Furthermore, these sharp lateral variations in crustal thickness correlate with Precambrian structures, suggesting that pre-rift structures influenced later rifting.