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Wednesday, June 28, 2023

URI ocean engineering professor appears in French television documentary on tsunami threat to French Riviera

Stephan Grilli continues years of work with European scientists

By Dave Lavallee 

DISCUSSING THE SCIENCE OF TSUANMIS: Stephan Grilli being interviewed in his lab for a French TV documentary. URI photos by Nora Lewis

University of Rhode Island Professor of Ocean Engineering Stephan Grilli has had a keen interest in the French Riviera for the past 25 years. But his visits have not been about taking in the yachting scene, the beaches, golf courses or even the Cannes Film Festival.

Instead, he has spent time in France since 1996 on four separate sabbaticals collaborating with French, Italian, United Kingdom and other European scientists to further his research on the threat of tsunamis to the French Riviera and preventing the loss of life and property. In fact, his last research trip to the area, from January to July 2022 led to the URI scientist being interviewed remotely by French journalist Marine Chassang for CAPATV, France’s largest producer of television news reports and documentaries.

A TSUNAMI SIMULATION: University of Rhode Island Professor of Ocean Engineering Stephan Grilli simulates the effects of a tsunami in his laboratory for Photographer Edward Bally.

In February, a cameraman recorded the interview live and captured video of Grilli demonstrating the effects of tsunamis using the wave tank in his laboratory at URI’s Narragansett Bay Campus.

The documentary ran June 21 on the French RMC television channel.

Grilli’s seven-month sabbatical last year, one of four awarded to him since the mid-1990s to conduct research in the area, was funded through the Fulbright Distinguished Tocqueville Chair Award, the most prestigious appointment in the Fulbright Scholar Program. Scholars are expected to work with host institutions in a spirit that promotes understanding and the sharing of research findings. His two main partners during this period were researchers at the University of Toulon and the University of Nice.

DESTRUCTIVE WAVE: A “tsunami” is about to destroy a small “village” in Professor Stephan Grilli’s wave tank.

“The Mediterranean area is one of the most seismically active in the world,” Grilli said, while referencing the Feb. 6 earthquake in Turkey, the largest in that country since 1939. “They have earthquakes in that region–Turkey, Greece, and southern Italy–all the time. When those earthquakes occur on and below the seafloor, they may cause tsunamis. The Mediterranean has had many damaging tsunamis, the most damaging of which, the largest catastrophe in modern history, was in the Mesina straits in 1908. We’ve published extensively on that. It killed 80,000 people.

“The tsunami was produced by a very small earthquake, a 7.2 magnitude,” Grilli said. “We created models that showed it should have created a tsunami of about 6 or 7 feet, about 2 meters, but 12 meters were measured on the shore, and so that’s about 40 feet. That’s been a little bit forgotten.”

Work conducted by his research group and a doctoral student, Lauren Schambach, showed that there was an underwater landslide triggered by the earthquake in 1908 on the seafloor of Sicily from the slope of Mount Etna.

That is why he has been conducting extensive research in the area of the French Riviera. He doesn’t want people in that region, where about 2 million people live and which attracts more than 10 million tourists each year, to forget about the threat.

“My latest research was built around tsunami detection in the Mediterranean by radar. In fact, I was actually working in France in 2013-14 during a sabbatical supported by the French that focused on the use of ocean radar for tsunami detection.”

The documentary focuses on the coastal area from Genoa, Italy, to Marseille, France, much of which is along the French Riviera. Grilli said the Ligurian faults are located on the seafloor about 20 miles offshore.

“Those faults have been the sites of several earthquakes, the largest one in 1887,” Grilli said. “It caused a tsunami in the fishing villages that are now the big cities of Nice and Cannes, which could have reached 2 to 3 meters in some locations. We have the data. Only about half of the fault was affected. But now the big question is when is the next portion going to cause an earthquake and subsequent tsunami?”

Even the expansion of the airport in Nice, which involved adding tons of sediment to extend a runway into the ocean, caused a tsunami in 1979. The sediment collapsed into the ocean, causing a tsunami that killed two people. Grilli said.

He and his colleagues have completed models of two scenarios about what could happen if the Ligurian faults become active again. They also researched what would happen if a major earthquake occurred on the coast of Algeria.

“If an earthquake occurred and caused a tsunami, all of France’s south coast would be affected,” Grilli said.

“It’s a question of preparing,” Grilli said, adding that the U.S. is a bit more prepared.

Grilli serves on the National Tsunami Hazard Mitigation Program, which is part of National Oceanographic and Atmospheric Administration’s National Weather Service.

NOAA provides funding to regional agencies facing the potential of tsunamis such as the Northeast Emergency Consortium, which supports Grilli and a colleague at the University of Delaware. The team conducts research covering the 14 East Coast states from Florida to Maine.

“We have maps that emergency managers can look at to prepare for tsunamis,” Grilli said. “In France, they are starting to do it. France, Greece, Italy and Spain created the European Center for Tsunami Forecasting, which is creating tsunami scenarios and simulations.”

Grilli talked about what it means to him as a researcher to see governments taking action.

“That’s what you wish for, that what you do is useful to society, especially something like this that can help save lives. You want to save lives by informing people. When the 2004 tsunami occurred in Indonesia, the local people knew about the dangers of a tsunami. And they were aware of what could happen. But many people were killed because those living in the resorts were curious, when the water began receding from the coast, they went looking. A little English girl, who had watched a documentary in school about tsunamis, ran up and down the beach with her dad telling the people about the tsunami, and she saved hundreds of people. That English girl’s actions show that basic knowledge can save lives.”

Grilli said he and his colleagues are doing similar things on a much larger scale.

“Look at Narragansett (Town) Beach during the summer, there are 5,000 people there. If you had a bad tsunami off the (continental) shelf somewhere, the stakes are much higher,” Grilli said.

“In France where the faults are close to the coast, it might take only 10 to 15 minutes for a tsunami to reach the Riviera, a region that also has very crowded beaches from May to October. You might feel some vibrations from an earthquake, then you get on with enjoying your day, and then you have a major catastrophe.”

EDITOR'S NOTE: Dr. Grilli was my nephew Chris O'Reilly's teacher and mentor from Chris's undergrad days through the completion of his Ph.D. in ocean engineering. Our whole family owes Dr. Grilli a lifelong debt of gratitude.   - Will Collette