The LVZ shows a reduction in velocity of about 3–6% with the effect being more pronounced with S-waves compared to P-waves.[9] As is evident from the figure, the reduction and depth over which reduction occurs varies with the choice of tectonic province, that is, regions differ in their seismic characteristics. Following the drop, the base of the zone is marked by an increase in velocity, but it has not been possible to decide whether this transition is sharp or gradual. This lower boundary, found beneath the continental lithosphere and oceanic lithosphere away from mid-ocean ridges, is sometimes referred to as the Lehmann discontinuity and occurs at about 220±30 km depth. The interval also shows a reduction in Q, the seismic quality factor (representing a relatively high degree of seismic attenuation), and a relatively high electrical conductivity.
The LVZ is present at the base of the lithosphere except in areas of thick continental shield where no velocity anomaly is apparent.