Seismic data is used to visualize the Earth's sub surface. This is achieved by measuring travel times of reflections from pressure waves propagating through the ground. Seismic data and interpretations of seismic data will therefore often have z values in travel time, not depth. In order to get a depth value for the a travel time valuesvalue, we need to do a depth conversion. A depth conversion combines the velocity of the pressure wave with the travel time to get a depth value.
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