Ancient Caribbean Tsunami May Have Altered Ecosystems

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As we know, the Caribbean is highly vulnerable to coastal hazards such as hurricanes, tsunamis, mudslides and floods. There is new evidence that an ancient tsunami caused dramatic long-term ecological changes in the Caribbean more than 3,000 years ago. Scientists investigated sediments from a coastal lagoon on the Caribbean island of Bonaire about 50 miles (80 kilometers) north of the Venezuelan coast.

Bonaire has not experienced a tsunami during the past 500 years of its recorded history. However, analysis of the size of sediment grains found on the island, the organic matter present in the sediment (such as animal remains and carbonate minerals), as well as other factors suggest that a devastating wave struck the island about 3,000 to 3,300 years ago.

[. . .] The researchers estimate the tsunami reached at least 820 feet (250 m) onshore. “Lagoons and valleys of the island might be inundated up to a kilometer (0.6 miles) or more, and the flat and low-lying southern tip of the island might have been entirely inundated,” Engel told OurAmazingPlanet.

This catastrophe apparently altered the coastal ecosystem and sedimentation patterns in the area. In the wave’s aftermath, a barrier of coral rubble separated a former mangrove-fringed bay from the open sea, transforming it into a highly salty lagoon that has persisted up to now. “Large tsunamis may occur on the ABC islands — Aruba, Bonaire, Curaçao — even though tsunamis have never been observed in historical times,” Engel said.

It remains uncertain where this tsunami might have come from. “The most likely source would be a local to regional tsunami triggered by an earthquake along the southern boundary of the Caribbean tectonic plate — that is, the coast of Venezuela,” Engel said. For instance, historical records suggest a devastating tsunami in 1530 was triggered by an earthquake near Cumaná, Venezuela.  In addition, a strong earthquake at the northeastern boundary of the Caribbean cannot be excluded as the tsunami’s cause either. For instance, the 1867 temblor in the Anegada Passage in the U.S. Virgin Islands triggered a tsunami that traveled across the Caribbean. “Further possible trigger mechanisms include submarine volcanic activity in the southern Antilles island arc, though these tsunamis tend to be local,” Engel said.

The wave may even have been a “teletsunami,” an oceanwide tsunami originating on the other side of the Atlantic.

For full article, see http://www.nbcnews.com/id/50643496/ns/technology_and_science-science/t/ancient-caribbean-tsunami-likely-altered-ecosystems/

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