A detailed¹ analysis of sediments³ from the island of Bonaire in the Caribbean presents convincing evidence for an extraordinary wave impact dating back some 3,300 years, even though no historical records of tsunamis⁵ exist for this island. Of particular interest are the consequences this large wave impact had on the island's ecosystem⁶. The sediments studied by the scientists suggested that this tsunami⁴ entirely⁷ changed the coastal⁸ ecosystem and sedimentation⁹ patterns in the area. The work by Dr. Max Engel and colleagues, from the University of Köln in Germany, is published online in Springer's journal, Naturwissenschaften -- The Science of Nature.

 

The Caribbean region is highly vulnerable to coastal hazards, including tropical cyclones¹⁰, earthquakes, volcanoes, and tsunamis. Even though the island of Bonaire has not experienced a tsunami during the past 500 years, which is the period of historical documentation, overwash（冲刷） deposits from a coastal lagoon¹¹（泻湖） provide evidence for at least one such event in prehistory.

 

Engel and colleagues investigated sediment² cores from Washington-Slagbaai National Park. They looked specifically at grain size distribution, carbonate content, organic matter, magnetic susceptibility and fauna¹²（动物群）. Their analyses showed that the sediments had criteria¹³ typically linked with tsunami deposits, consistent with a tsunami with a maximum age of 3,300 years.

 

The authors conclude: "This single catastrophic event is of long-term ecological¹⁴ significance. Formation of a barrier of coral rubble¹⁵ was triggered by the tsunami separating a former inland bay from the open sea and turning it into a highly saline（盐湖） lagoon which persists until today. Further studies of the geology of tsunamis, using well-dated deposits, are required over the entire Caribbean to reconstruct reliable patterns of magnitude, frequency and spatial¹⁶ occurrence of tsunami events and their environmental impact."

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