But that doesn't mean that it's the largest such shift ever to have been caused by an earthquake, cautioned Chris Goldfinger, director of the Active Tectonics and Seafloor Mapping Laboratory at Oregon State University.

The March earthquake was, however, the first time that scientists have directly measured such a slippage thousands of feet of underwater.

"Any magnitude 9 earthquake will have similar values," said Goldfinger, who was not part of the study team.

For instance, the 2004 Sumatra earthquake may have moved the seabed by as much as 100 feet (30 meters), he said by email.

(Related: "Japan Earthquake Shortened Days, Increased Earth's Wobble.")

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