Scientists revisit Anegada to study causes of catastrophic event

Scientists are currently in the Territory conducting an eight-day analysis of the geological effects of Hurricane Earl on Anegada to ascertain whether a hurricane impact was responsible for the catastrophic overwash that occurred between 1650 and 1800.

According to the Director of the Department of Disaster Management Sharleen DaBreo, this study is ongoing and relevant because scientists are concerned that the Subduction Zone in this part of the region could create a significant earthquake or tsunami event in the future.

She said Anegada is ideal to search for geological records of ancient earthquakes and tsunamis because of its close proximity to the zone.

Dr. Brian Atwater and Mr. Robert Halley of the United States Geological Survey (USGS), Dr. Martitia Tuttle of M. Tuttle & Associates and Ms. Zamara Fuentes of the Puerto Rico Seismic Network (PRSN) said they are comparing Hurricane Earl’s sediment layers with those between 1650 and 1800.

Dr. Atwater said that 1650 is cited as the earliest possible date based on radiocarbon dating.  He added that 1800 was calculated based on written accounts from members of the Methodist Church on Anegada.  

He said, “We did find evidence of a catastrophe on Anegada, an overwash was evident on a big portion of the island, and we believe that this catastrophe can be explained by the tsunami that came from the Lisbon earthquake in 1755.” Photo Caption - Dr. Brian Atwater making a presentation before they head off to Anegada with information based on their 2008 and 2009 findings. Photo courtesy of DDM

The study, which was initiated in 2008, and subsequently in 2009, is being carried out in salt ponds that have been relatively undisturbed by crabs and other organisms because of the high salt content.

The team of scientists will present their findings to government officials. The study will then be published in the Natural Hazards scientific journal. Copies of the publication and access to the data will be given to the Government. This research is funded by US Nuclear Regulatory Commission (USNRC).

Overwash is the flow of water and sediment over the crest of the beach that does not directly return to the water body (such as ocean, sea, bay or lake; hereafter, ocean) where it originated after water level fluctuations return to normal.

A subduction zone is an area on Earth where two tectonic plates move towards one another and one slides under the other.

Radiocarbon Dating, or carbon dating is probably one of the most widely used and best known absolute dating methods. It is the archaeologist's tool kit that has revolutionized archaeology by providing a means of dating deposits independent of artifacts and local stratigraphic sequences


Back To Top