The National Oceanic and Atmospheric Administration says a 6-foot wave that hit the East Coast earlier this month was a rare tsunami.
The West Coast and Alaska Tsunami Warning Center said the source of the wave is "complex and under review," but they believe it was caused by a strong storm and perhaps even the "the slumping at the continental shelf east of New Jersey."
The weather service says that Brian Coen, who was spear fishing near Barnegat Inlet in New Jersey, saw the effect of the tsunami first hand.
He told the weather service that he noticed an outgoing tide that lasted a couple of minutes and exposed rocks that had been submerged. That was followed by a big six-foot wave.
The Asbury Park Press, which covers the Jersey coast, talked to Paul Whitmore, director of the tsunami center.
He explained the weather system that moved through the area may have changed the air pressure enough to "generate waves that act just like tsunamis." When that happens, the wave is called a "meteotsunami" — in other words a tsunami caused by meteorological conditions, not seismic activity.