Thursday, March 05, 2015

The Caribbean’s Hidden Tsunami Potential (Revisited)



# 9784


Although little appreciated outside of the Indian and Pacific Ocean basins, tsunamis are a rare, but genuine threat to almost any coastal region of the globe.  Today we’ve word of a new study that finds evidence that a major tsunami struck the Yucatan coastline between 1500 and 1900 years ago.


A little over a year ago – in The Caribbean’s Hidden Tsunami Potential – we looked at a brief history of some of the destructive waves that have been spawned in the tropical waters to our south. 


In that blog I presented a  list of known or suspected Atlantic & Caribbean Tsunamis, starting off with the Great Lisbon Earthquake of 1755 (see A Look At Europe’s Seismic Risks), which also included:


    • November 1, 1755 - Lisbon, Portugal
    • October 11, 1918 - Puerto Rico
    • November 18, 1929 - Newfoundland
    • August 4, 1946 - Dominican Republic
    • August 18, 1946 - Dominican Republic
    • November 14, 1840 - Great Swell on the Delaware River
    • November 17, 1872 - Maine
    • January 9, 1926 - Maine
    • May 19, 1964 - Northeast USA


    • June 9, 1913 - Longport, NJ
    • August 6, 1923 - Rockaway Park, Queens, NY. An article on triplicate waves."
    • August 8, 1924 - Coney Island, NY. Contains a discussion, “An Observed Tsunami Building In Coastal Waters?"
    • August 19, 1931 - Atlantic City, NJ
    • September 21, 1938 - Hurricane, NJ coast.
    • July 3-4, 1992 - Daytona Beach, FL


The last suspected entry – the infamous Daytona Beach `rogue wave’ of 1992 - was described by witnesses as being between 10 and 18 feet tall, slammed onto a 27 mile stretch of Florida Beaches without warning and smashed hundreds of cars, causing as many as 75 (mostly minor) injuries.


In A Brief History of Tsunamis in the Caribbean Sea (2002), researchers James F. Lander, Lowell S. Whiteside, and Patricia A. Lockridge of NOAA’s National Geophysical Data Center  list descriptions of of  91 reported  waves over the past 500 years that might  have been  tsunamis  within  the Caribbean  region. 


Of  these, the authors judged 27 to be actual tsunamis, while nine more were considered `likely’ tsunamis’.


Credit - A Brief History of Tsunamis in the Caribbean Sea


Adding to this list, today we’ve a press release from the University of Colorado at Boulder which describes recently discovered evidence suggesting  a major tsunami struck along the eastern shore of Yucatan, Mexico within the past 2,000 years.


Public Release: 5-Mar-2015

Evidence indicates Yucatan Peninsula hit by tsunami 1,500 years ago

University of Colorado at Boulder

The eastern coastline of Mexico's Yucatan Peninsula, a mecca for tourists, may have been walloped by a tsunami between 1,500 and 900 years ago, says a new study involving Mexico's Centro Ecological Akumal (CEA) and the University of Colorado Boulder.

There are several lines of evidence for an ancient tsunami, foremost a large, wedge-shaped berm about 15 feet above sea level paved with washing machine-sized stones, said the researchers. Set back in places more than a quarter of a mile from shore, the berm stretches for at least 30 miles, alternating between rocky headlands and crescent beaches as it tracks the outline of the Caribbean coast near the plush resorts of Playa del Carmen and Cancun.

Radiocarbon dates of peat beneath the extensive berm indicate a tsunami, which may have consisted of two or even three giant waves, likely slammed the coastline sometime after A.D. 450. In addition, ruins of Post-Classic Mayan structures built between A.D. 900 and 1200 were found atop parts of the berm, indicating the tsunami occurred prior to that time.


One implication of the Yucatan tsunami is the potential destruction another one could cause. While the geologic evidence indicates tsunamis in the region are rare -- only 37 recorded in the Caribbean basin since 1492 -- the Yucatan coastline, which was only lightly populated by Mayans 1,500 years ago, is now home to a number of lavish resort communities and villages inhabited by some 1.4 million people.

"If such an event occurs in the future, it would wreak havoc along the built-up coastline, probably with a great loss of life," said Benson. But it's far more likely that powerful hurricanes like the Class 5 Hurricane Gilbert that made landfall on the Yucatan Peninsula in 1988, killing 433 people in the Caribbean and the Gulf of Mexico and causing more than $7 billion in damage, will slam the coastline, said the researchers.


In 2013 the  USGS warned the Earthquake/Tsunami Hazard in Caribbean Higher Than Previously Thought, stating `Enough strain may be currently stored in an earthquake zone near the island of Guadeloupe to cause a magnitude 8 or larger earthquake and subsequent tsunami in the Caribbean’


Beyond damage to local islands, it is not inconceivable that a large Caribbean or Atlantic origin tsunami could negatively impact the coastlines of the Gulf states, the Eastern Seaboard, Mexico, Central and South America, and even parts of Africa and Europe.


You can access current Tsunami warnings and arrival times at the  Pacific Tsunami Warning Center.


As far as what to do before a tsunami threatens, READY.GOV has a Tsunami Awareness Page with helpful hints.NOAA  provides several useful documents, including a Tsunami Zone PDF (see below) and Tsunami Web page.


Tsunamis, while comparatively rare, are just one of scores of possible disaster scenarios that one can find themselves suddenly thrust into.


When you add in the risks from earthquakes, hurricanes, tornadoes, floods, blizzards, and other – even more common – emergencies, it makes sense to maintain a general level of preparedness against `all threats’.

Everyone needs an appropriate disaster plan, just as everyone should have a good first aid kit, a `bug-out bag’, and sufficient emergency supplies to last a bare minimum of 72 hours.


As the graphic above from NOAA advises, people should consider maintaining a 2-week supply of supplies in their home.  A topic I address in When 72 Hours Isn’t Enough.


As we move into the spring severe storm season, and ultimately back into the Atlantic Hurricane season, now is a good time to review and refresh your emergency preparedness plans.