An unprecedented tidal wave hit the mascarene islands on Saturday night. Waves with average height of 5 to 6 metres and peaks of 10 to 11 metres caused considerable damage to coastal habitations. These coincided with the high tides at 10.30 pm. Eight persons are reported missing, one in Mauritius, five in Rodrigues and two in Reunion Islands.
Information from the Meteorological Services reveal that these waves have been caused by an extra-tropical storm some 2000 km to the South of the Mascarenes. With a central pressure of 950 hPa it may be compared to intense tropical cyclone Gervaise which hit Mauritius in 1975 when a maximum gust of 175 km/h was recorded. Extra-tropical depressions are common during this transition period to winter which is also characterized by strong anticyclones to the south. The southern coasts have been mainly affected.
Some people thought it was a tsunami. But tsunami is a different phenomenon. It is triggered by earthquakes in the deep seas. Its waves travel over very long distances. They can enter several meters inland with devastating effects. Tidal waves occur at the surface of the sea as a result of strong sustained winds.
Although this time the waves have been phenomenal, tidal waves have been observed in the past in 1915, 1976, 1987 and 1995 during similar periods of the year. It is therefore not a new phenomenon as some people tend to believe.