Ultrasonic velocity refers to the speed at which ultrasonic waves travel through a material, commonly used in geophysical surveys to characterize rock properties. Ultrasonic velocity is significant in geophysics for understanding the elastic properties of rocks, subsurface imaging, and the detection of fractures and faults.
Reference: Krautkrämer, J., & Krautkrämer, H. (1990). “Ultrasonic Testing of Materials.” Springer.