The low-velocity zone in the mantle is called?

The low-velocity zone in the mantle can also be called the peridotite mantle lithosphere. This is the zone that starts at the depths of about $50 \text{ km}$ and ends at the depths of about $300 \text{ km}$, the thickness of the low-velocity zone can vary. When passing through this zone primary seismic waves are slowed and secondary seismic waves are slowed or absorbed due to partial melting of the rock.