The radial anisotropy model (I-L) is plotted with respect to an isotropic reference. The dominant feature above 200 km is the faster Vsh than Vsv or Xi1 everywhere. Abnormal Xi is spotted beneath the northeastern Pacific rise, the Rio Grande Rift, the Nevada Basin and Range, and the central Trans-Hudson Orogen, suggesting Vsv is faster in those regions. At 300km, most of the radial anisotropy has disappeared, except beneath the western US where Xi 1, indicating a probable deep origin of the anomaly. A negative Xi anomaly is observed in the vicinity of the East Pacific Rise at all depths (I to L), suggesting a probable deep ( 300km) origin of this anomaly.
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