 Ultra-low velocity zone

An Ultra-Low Velocity Zone (ULVZ) is a region in the Earth's mantle characterized by exceptionally slow seismic wave speeds, particularly the speeds of seismic waves generated by earthquakes. These zones are typically located at the base of the Earth's mantle, just above the outer core, and can be detected using data from seismic waves, which are affected by the temperature, pressure, and composition of the materials they pass through.