Dictionary:Low-velocity layer, low-velocity zone (LVL, LVZ)

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{{#category_index:L|low-velocity layer, low-velocity zone (LVL, LVZ)}} 1. Near-surface aerated sediments that have very low velocity, also called weathering or weathered layer. The LVL is important in seismic interpretation because it can have marked effect on reflection arrival times. The low-velocity zone often varies in thickness, lithology, density, velocity, and attenuation effects. The velocity of the layer is comparatively low, commonly of the order of 500 m/s. 2. A layer whose velocity is lower than that of shallower refractors. See blind zone. 3. Any layer bounded on both sides by layers of higher velocity. Such a layer can carry channel waves (q.v.). 4. LVZ often means the B-layer in the upper mantle (see Figure E-1) from 60 to 250 km deep, where velocities are about 6% lower than in the uppermost mantle. LVZ may also mean the region just inside the Earth’s core.