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Tuesday, April 23, 2019

Maritime Logistics Professional


Posted to Maritime Musings (by on September 13, 2013

A large amplitude seiche oscillation generated by unusual weather conditions

A meteorological tsunami (or meteotsunami) is a tsunami created by air pressure disturbances, such as atmospheric gravity waves, roll clouds, pressure jumps, frontal passages, or squalls, occurring over large bodies of water and causing barotropic waves.  The waves become amplified as they enter shallow water and can become excessively amplified in the shallow water of a funnel-shaped bay or enclosure.  Although they tend to be of smaller height than earthquake or underwater land-slide generated tsunamis, they are functionally the same, differing only in their origin.  Meteotsunamis have been recorded in coastal areas worldwide.  In June 1954, one struck the shore of Lake Michigan at Chicago.  It was ten feet in height, killed seven people, and caused significant damage.  Similar events were recorded in Daytona Beach in 1992 and in Boothbay Harbor in 2008.  The largest recorded meteotsunami (fifteen feet in height) struck Nagasaki Bay in 1979, also resulting in loss of life.  Meteotsunamis strike Japan with sufficient regularity to have acquired their own name – abiki.  On 27 June 2011, a meteotsunami caused swells on otherwise calm Mounts Bay near the southwest end of Cornwall in the UK.  Tourists strolling along the walkway between the mainland and the tidal island of St. Michael’s Mount east of Penzance found themselves suddenly in knee-deep water.  As quickly as the high water came, it disappeared.  Scientists researching the event found that, the night before, a strong storm arose in the Bay of Biscay, 300 miles to the south.  The storm generated a small meteotsunami, which became of greater height when it entered the shallow waters of funnel-shaped Mount’s Bay.