The map above allows comparison between P-wave tomography of SNEP+ dataset assuming a 1-D starting model, a 1-D starting mode but with Great Valley stations corrected for sediment, and an inversion starting from Josh Stachnik's ambient noise tomography above 55 km (converted from S to P with regression of Brocher (1995)). The ambient noise tomography itself as converted to P-wave anomalies is shown in the righmost collection of maps. The region shown is roughly coincident with the area inverted in the ambient noise tomography; this includes the core SNEP study area. Other maps show inversions over a broader region.