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It’s called “multibeam” because unlike the first single-beam sonars, which sent out one signal or ping, multibeam sonar sends out a whole group of pings at once. Multibeam sonar can cover a larger area than a single beam can.

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Multibeam sonar sends out many beams of sound waves to the sea floor. The equipment is usually mounted on the bottom of the boat.

How Is Sonar Used to Map the Sea Floor?

Scientists use two kinds of sonar to map the sea floor: multibeam and side scan.

Multibeam Sonar

Multibeam measures the depth of the sea floor. It measures the length of time it takes for the sound to travel from the boat to the sea floor and back as an echo.

Scientists use the time measurements to figure out how deep the water is.

Did you know?

Press play button to start the movie.

In this movie, a survey ship with a multibeam sonar measures the depth of the sea floor. These depth measurements are then used to create rainbow-colored maps. In general, red is used to show shallow depths and blue or purple for deeper depths. Can you see the shallowest point the ship surveyed?

Movie Credit: U.S. Naval Oceanographic Office

Click here if you want to see the movie in Quicktime.

You may need to download: Quicktime |  Windows Media

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