Caribbean: Honing tsunami warning system

Reading time 5 min.

Frequent Caribbean earthquakes and concern about tsunamis prompted the island nations, the UNESCO Intergovernmental Oceanographic Commission (IOC) and neighbors, including the United States, to build on local experience with hurricanes and volcanoes to establish a regional warning system for tsunamis and other coastal hazards.

While no warning system can prevent naturally occurring hazards like earthquakes and storms, having an early warning system can minimize the loss of life and destruction that accompanies these hazardous events, giving people time to prepare.

The effort began in 2005. Today, the islands are protected by real-time seismic stations for detecting earthquakes, three deep-ocean detection systems (DARTs) for tsunami waves, and a growing number of stations for monitoring sea level. By the end of the year, the United States with the University of Hawaii Sea Level Center and the Puerto Rico Seismic Network will have installed 11 more sea-level stations in the region.

After the magnitude 9.0 Indian Ocean earthquake and tsunami that took 230,000 lives in 2004, the U.S. National Oceanographic and Atmospheric Administration (NOAA) has helped enhance the Caribbean’s warning capacity, Jenifer Rhoades, tsunami program manager for NOAA’s National Weather Service, said in a recent interview.

With the U.S. Geological Survey [USGS], she said, “we enhanced the seismic network in Puerto Rico and the U.S. Virgin Islands, and we are working with the USGS and other international partners to enhance the seismic capability elsewhere in the Caribbean.”

With IOC oversight and coordination, and technical and financial help from many nations, initial seismic and tsunami warning systems are in place in the Pacific and continue to be improved in the Indian Ocean, the northeast Atlantic and Mediterranean, and the Caribbean.

Around-the-clock coverage

The Caribbean region consists of 7,000 islands, islets, reefs and cays, and under the clear-blue Caribbean Sea are deep-sea trenches and fault zones between tectonic plates where geologic stresses breed earthquakes like the one that struck Haiti January 12.

The level of seismic activity in most of the Caribbean is considered moderate to severe. In the past three years, according to the University of the West Indies Seismic Research Centre, at least three earthquakes greater than magnitude 7.0 ― the strength of Haiti’s deadly quake ― have occurred in the Caribbean.

Across the islands, meteorological services or disaster response agencies in 23 countries and territories provide around-the-clock coverage, and the United States is helping establish a Regional Tsunami Warning Center at the University of Puerto Rico-Mayaguez.

With funding provided by the U.N. Development Programme, Barbados has agreed to host a Caribbean Tsunami Information Center to help educate local communities about how to respond to tsunami watches and warnings and where to go in an emergency.

Until the regional warning system is operational, NOAA’s Pacific Tsunami Warning Center (PTWC) in Ewa Beach, Hawaii, is providing interim tsunami watch services for the region and its West Coast and Alaska Tsunami Warning Center in Palmer, Alaska, is providing tsunami warnings for U.S. territories in the Caribbean.

“In the first week of February we are having a training for seismic network operators, so we are accelerating the work of the Seismic Research Centre in Trinidad, which is part of the University of the West Indies,” Bernardo Aliaga, technical secretary for UNESCO’s Intergovernmental Coordination Group for the Caribbean Tsunami Warning System, said in a January 26 interview.

“We are working with FUNVISIS [Fundación Venezolana de Investigaciones Sismológicas] in Venezuela and seismic networks in Central America, particularly INETER [Instituto Nicaragüense de Estudios Territoriales],” Aliaga said. “This creates a dense network of seismometers that enable PTWC, and later the Caribbean warning center, to rapidly locate and determine the magnitude and epicenter of an earthquake” in the Caribbean region.

Tsunami warnings

All tsunami warnings start with earthquake monitoring devices called seismic stations. All over the globe, nations, universities and technical consortiums maintain networks of seismic stations that can detect earthquakes wherever they happen and use communications systems and satellites to send the data to warning centers like the USGS National Earthquake Information Center in Colorado or the PTWC in Hawaii.

Even the Comprehensive Nuclear Test Ban Treaty Office (CTBTO), whose International Monitoring System uses seismic stations and other kinds of technology to listen for nuclear explosions worldwide, is helping nations bolster their tsunami warnings.

“We have agreements to provide data from close to 40 seismic and hydroacoustic [echo sounder] stations to tsunami warning alert centres in the United States, Australia, Japan, the Philippines, Indonesia and Thailand,” Annika Thunborg, chief of public information for the CTBTO Preparatory Commission, wrote in a January 27 e-mail. The centers use the CTBTO data directly to issue tsunami alerts, she said.

“An arrangement with Malaysia is also in the pipeline and discussions are being conducted with other countries in the region of the Indian and Pacific oceans,” Thunborg added. “Countries in Latin America and the Caribbean have expressed an interest in establishing regional tsunami warning centres and to use CTBTO data for tsunami warning alert purposes. We at the CTBTO stand ready to assist them whenever it is suitable for them.”

At the warning centers, experts determine the earthquake’s magnitude and location from the seismic data, then use data that come in later from sea-level gauges and DARTs to determine whether an earthquake has generated a tsunami. Experts evaluate the threat and issue alerts to each affected region or country, and local officials decide whether the threat warrants alerting the public.

“There has been progress in improving the detection and the capability to generate our warning products to the Caribbean,” NOAA’s Rhoades said. “There is more work to be done, though, in how that information is disseminated to the public and improving outreach and education to ensure that people know how to respond.”

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