In 2009, a group of researchers studied the geology of Anegada looking for evidence of past tsunamis. Photo: PROVIDEDIn the end, 14 countries were hit by the tsunami. Many small resort or fishing towns in the region were levelled. Nearly two million people were displaced, and more than 230,000 people died.

Hardly anyone remembered the last time a major tsunami had struck outside of the Pacific Ocean, but in the face of such massive destruction, there was no more room to deny the potential danger.

There was a bright spot amidst all the death and destruction. A decade of warnings from scientists who study the earth and its movements finally gained traction, said Christa von Hillebrandt-Andrade, director of the National Oceanographic and Atmospheric Administration’s Caribbean Tsunami Center.

“We were aware of the danger and we had tried to raise the awareness level,” Ms. von Hillebrandt-Andrade said. The former head of the Puerto Rico Seismic Network added that records show that more than 75 tsunamis have struck the region.

However, compared to the Pacific, where approximately 80 percent of tsunamis occur, tsunamis are relatively rare here, according to Ms. von Hillebrandt-Andrade.

“Our biggest enemy is its infrequency,” she said. “It just falls off the agenda of families and governments.”

But after the Boxing Day disaster, proposals to explore the possibility of establishing a tsunami warning system similar to what NOAA already operates in the Pacific got fast-tracked. In 2010, Ms. Hillebrandt-Andrade was named director of the new Caribbean Tsunami Center, which spearheaded a regional tsunami drill this March.

The centre’s goal is to help predict tsunamis by using sensors to send satellite messages about post-earthquake sea-level changes. Currently, there are four sensors in the Caribbean, out of 50 worldwide.

But there is more work to be done before the system will function reliably, and progress is not as fast as some would like. At a Kingston, Jamaica tsunami-preparedness workshop in April, officials said funding setbacks have pushed back plans for the Caribbean warning system.

A new timeline calls for a larger network of sensors to be installed and operational by 2014. In the meantime, the CTC, based at the University of Puerto Rico at Mayaguez, continues to work with UNESCO, the Caribbean Disaster Emergency Management Agency and local governments to help prepare for the worst.

Often, it takes a nearby disaster to convince people to pay attention to the risk for themselves, said Sharleen DaBreo, director of the Department of Disaster Management in the Virgin Islands.

The DDM held the first earthquake and tsunami drill in the territory in 2009, and at the time, the public didn’t fully embrace the exercise, she said.

“Then Haiti occurred and the question of earthquakes in the Caribbean came to the forefront,” Ms. DaBreo said.

Haitian officials reported that 300,000 people were killed by the 2010 quake and about one million were left homeless, although a report commissioned by the United States government and leaked to some US news agencies last month said those numbers are greatly exaggerated. The quake was estimated to have caused about $14 billion in damage, and sparked an immediate aid response worldwide.

In the VI, organisations like the BVI Red Cross and the Lions and Rotary clubs joined forces to collect and donate some $300,000, plus non-perishable items, to the reconstruction and relief efforts.

And while it got much less attention in light of its relatively minor damage, the Haiti quake — a magnitude 7.0 — also caused a tsunami.

According to BBC reports a month after the quake, the draw-down, or receding of the ocean that often precedes a tsunami, could be seen near the Dominican Republic border. In Haiti, a wave up to nine feet tall hit parts of the Port-au-Prince shoreline, killing a family of three.

And with the memory of Haiti still fresh, this year’s VI earthquake and tsunami exercise saw widespread participation — and not just of schoolchildren and government workers. The March drill had the staff of law offices, health clinics and other private-sector businesses heading to high ground, too.

Looking back

The last time a tsunami of note hit the VI was 1867. Estimates suggest that an earthquake with a magnitude between 7.0 and 7.5 with an epicentre in the Anegada Trough triggered the tsunami, which sent “high waves” or observable tide changes as far as Venezuela. Twenty-three people were killed in the USVI.

Even farther back in history, geologists suspect, a tele-tsunami, or tsunami triggered by a quake far away, likely struck Anegada, said Dr. Brian Atwater, a self-described “geological detective” and geology professor at the University of Washington.

By carefully examining the soil in Anegada, Dr. Atwater and his team discovered recently that ocean water washed over much of the island sometime between 1650 and 1800.

After examining written records from as early as the late 1700s, and radiocarbon dating the sediment on the island, Dr. Atwater thinks it’s most likely that Anegada was struck by a tsunami generated by a 1755 earthquake near Lisbon, Portugal. He added that because the wave struck on the opposite side of the island from The Settlement, there likely would have been no eyewitnesses.

“That whole side of the island was just for cattle grazing,” he said.

At the time of the 1867 tsunami, the VI still was basically a farming and fishing community, with some minor trade in Road Town.

Witnesses reported 10- to 12-foot-high waves in Road Harbour, and the water probably reached to the base of what is now Joe’s Hill Road, said Glenn Ashmore, author of These Rocky Shores: A Sailor’s Guide to the Geology of the British Virgin Islands. Sopers Hole was reportedly badly damaged, and many structures along the coast in Road Town were destroyed, according to the amateur geological historian.

This was much milder than the wall of water described in Frederiksted in the United States Virgin Islands (see sidebar), but Mr. Ashmore said Tortola may have been spared by its natural protection.

“All of Wickhams Cay was mangroves back then,” he said. Just as mangrove forests and coral reefs protect the territory’s beaches from stormy seas, he explained, they would also absorb some of the energy of a tsunami, causing it to slow down and lose some of its size and force.

Today’s risk

Almost a century and a half later, the VI has changed. Thousands of people commute to Road Town daily, and many of the territory’s most crucial services – water, power and the hospital – are literally a stone’s throw from the sea.

High population density and heavy coastal development are the main reasons tsunamis are potentially so deadly in the Caribbean, Ms. von Hillebrandt-Andrade told other scientists at a Puerto Rico workshop in February. The resulting risk means increased seismic monitoring is crucial, she advised.

In the VI, coastal development is almost unavoidable, according to Ms. DaBreo.

“We have a challenging place to build in,” Ms. DaBreo said. “We have a very narrow coastline, but we also have steep hillsides.”

Throughout the territory’s history, builders have had to balance the risks. Building close to shore means the property is subject to the dangers of the sea, including tsunamis, but building on a hillside means worrying about erosion and possible landslides.

There’s a modern risk, too: reclaimed land. Wickhams Cay is the largest example of reclamation, a process by which land is created artificially. The practice is common in much of the world, but in terms of seismic activity, it can be downright scary.

“Wherever you have reclaimed land, you have a risk of liquefaction,” Ms. DaBreo said of a process by which earthquakes or saturation cause soil to act like quicksand.

According to media reports from Japan in the wake of the March 11 earthquake and tsunami, liquefaction is the reason for extensive damage to Urayasu, a community 186 miles away from the epicentre of the quake, which was built on reclaimed land.

Managing the risk

Throughout the Caribbean, many officials are now taking a proactive approach when it comes to tsunamis. Many governments distribute tsunami-warning brochures so that residents and tourists alike can recognise the signs of a tsunami and react accordingly. In some coastal communities, signs have been erected to remind people that if they feel the earth shaking, a tsunami could be on the way.

In a region with such a high volume of transient residents and visitors, these educational campaigns are critical, but difficult, Ms. von Hillebrandt-Andrade said.

“Both the winter birds and tourists need to also be educated and prepared for events like tsunamis, but their short time on the island and the fact that they are on vacation makes them harder to engage and educate,” she said.

In the VI, brochures and practice drills are the highly visible efforts, but government has taken steps recently toward building a more prepared territory.

DDM has partnered with the Town and Country Planning Department to develop a hazard risk assessment, which TCP requires for many developments, Ms. DaBreo said.

“We provide them advice on what to consider during design and construction,” the DDM director explained. The potential hazards range from proximity to a ghut to a rise in sea level caused by global warming.

Planners now recommend that new developments have a contingency plan for emergencies that occur either during construction or after the project is completed, including a tsunami plan, she said.

“There was some resistance in the beginning because people felt that we were adding another step,” Ms. DaBreo said, adding that thanks to one-on-one sessions with planners, many developers have expressed their support of the risk assessments.

This broad buy-in of the importance of planning is perhaps the most important factor in preparing for such a rare but potentially deadly disaster.

“Because the reality is that the hazards are not going to go away,” Ms. DaBreo said, “we have to live with them.”

(This report appeared in the June 23, 2011 issue.)