The tsunami could soon hit major cities in or near the Mediterranean, including Marseille, Alexandria and Istanbul, with almost 100% probability that the wave will reach more than a meter high in the next 30 years, according to UNESCO.
The risk of a tsunami in Mediterranean coastal communities is expected to rise sharply with rising sea levels. While communities in the Pacific and Indian Oceans, where most tsunamis occur, were often aware of the dangers, they were underestimated in other coastal regions, including the Mediterranean, said UNESCO.
The UN educational, scientific and cultural organization has now said that five endangered communities in the Mediterranean will join 40 more tsunami-ready cities in 21 countries by next year. In addition to Marseille, Alexandria and Istanbul, these include Cannes and Chipiona, a city on the Spanish Atlantic coast near Cádiz.
The “tsunami-ready” program is part of a wider UNESCO effort launched ahead of next week’s UN Ocean Conference in Lisbon to ensure that all vulnerable communities know what to do in the event of a 2030 tsunami.
“The 2004 and 2011 tsunamis were awakening,” said Bernardo Aliaga, chief tsunami expert at UNESCO. “We have come a long way since 2004. We are safer today. However, there are gaps in preparedness and we need to improve; we need to make sure that visitors and communities understand the warnings. “
The Indian Ocean tsunami, Boxing Day 2004, the deadliest in history, killed an estimated 230,000 people in 14 countries, while a magnitude 9.1 earthquake and tsunami in 2011, which reached a height of almost 40 meters (130 feet), killed 18 000 people. Japan.
Since the 2004 Indian Ocean tsunami, the Pacific Tsunami Warning Center for the United States has responded to 125 tsunamis, an average of seven a year.
“The upstream part is in good condition,” Aliaga said. “12 tsunami warning centers covering most of the ocean, including the Mediterranean, have been set up.”
The warning centers include five in the Mediterranean and the North-East Atlantic, including Greece, Turkey, Italy, France and Portugal.
“The risk of a tsunami is underestimated in most areas, including the Mediterranean,” Aliaga said. “Events are not very common and risk is not passed on from one generation to the next.
“We have to get the news out,” he added. “There is no doubt about that in the Mediterranean: not if, but when.”
One of the deadliest earthquakes in history struck Portugal on All Saints’ Day in 1755, causing a 6-meter tsunami in Lisbon and Cádiz. As many as 50,000 people died in the earthquake, but many unsuspecting others died in the ensuing fires and tsunamis.
A tsunami only 1.5-2 meters high can lift cars off the ground, while smaller waves can cause water walls moving at 40 mph (65 km / h).
“The warning is not a complete story,” Aliaga said. “The second part is community preparedness – how people behave and react. That’s the way to go. “
He cited the case of Tilly Smith, a 10-year-old British girl who brought 100 people, including her family, to safety during the 2004 tsunami. The school’s geography teacher told her to evacuate as soon as she saw the receding water.
Rising sea levels, which are increasing the impact of the tsunami on coastal communities, are “another reason to increase the pace of our work,” he said.
“The connection is that rising sea levels are increasing the impact of the tsunami.”
A 2018 study modeling the tsunami in Macau, China, found that rising sea levels increased the risk of tsunamis because they could travel further inland. The incidence of tsunami floods increased 1.2 to 2.4 times with sea level rise of 45 cm and 1.5 to 4.7 times with increase of 90 cm, the study found.
Authorities in Alexandria, Istanbul, Marseille, Cannes and Chipion are working on tsunami preparedness, including evacuation signs and procedures, as well as tourist warning plans, Aliaga said.
“We want 100% of communities where there is a proven danger to be ready to respond by 2030,” he said. “They will have evacuation maps, drills and 24-hour warnings.”
The alerts were triggered about 10 minutes after the quake, he said, and can take the form of anything from speakers to WhatsApp reports.
“If it’s a local tsunami, you have a maximum of 20 minutes before the first wave hits.” The second wave is larger and comes 40 minutes after the first. You still have a chance to escape. “
Vladimir Ryabinin, executive secretary of the UNESCO Intergovernmental Oceanographic Commission, said: “More than 40 communities in 21 countries are now safer because they have implemented our tsunami-ready program. If we are to meet this global challenge by 2030, we need to expand our agenda very quickly. ”