echo sounding

The concept is similar to echo sounding: seismic waves are reflected at interfaces where rock properties change and the round-trip travel time, together with velocity information, gives the distance to the interface. The relief on the interface can be determined by mapping the reflection at many locations. For simple situations…

…though not without problems, is echo sounding, widely used today, in which a sound pulse travels from the vessel to the ocean floor, is reflected, and returns. By calculations involving the time elapsed between generation of the pulse and its return and the speed of sound in water, a continuous…

…waters, and the introduction of echo sounding in the early 20th century marked a great improvement. It was made possible by the invention of electronic devices for the measurement of short intervals of time. Echo sounding depends on timing the lapse between the transmission of a short loud noise or…