The world is going through a period of climate change and extreme environmental and natural phenomena at all levels, from last year’s earthquakes in Turkey and Morocco to the floods and torrents in Syria. We have begun to seek to anticipate and predict disasters in order to put in place warnings and protect people’s lives.

One warning that has recently appeared in Egypt is that of a tsunami, or giant wave, in the Mediterranean Sea that could hit the country’s coastline. The word “tsunami” consists of the Japanese words “tsu” (meaning port) and “nami” (meaning wave). A tsunami can be a series of huge waves created by underwater disturbances and is usually associated with earthquakes that occur below or near the ocean.

Volcanic eruptions, submarine landslides, and falling coastal rocks can also generate tsunamis, and a large asteroid could also do so by impacting the ocean. Tsunamis arise as a result of vertical movements on the sea floor that cause the displacement of the water mass. They often appear as walls of water and can be dangerous for several hours, with waves arriving every five to 60 minutes on the coastline.

The first wave may not be the largest, but often the second, third, fourth, or even subsequent waves are. After one wave overflows or floods inland areas, it retreats towards the sea again, carrying with it much inland debris. The next wave then rushes ashore within minutes, carrying with it much of the floating debris destroyed by previous waves.

Earthquakes generated by movements along faults associated with plate boundaries can cause tsunamis. Most strong earthquakes occur in subduction zones where parts of the ocean floor slide beneath a continental plate or a smaller ocean plate.

Not all earthquakes cause tsunamis, and there are four conditions necessary for them to do so. The earthquake must occur under the ocean or as a result of the sliding of materials in the ocean. It must be strong and no less than a magnitude of 6.5 on the Richter Scale. It must occur at a shallow depth and less than 70 km below the Earth’s surface. It must cause vertical movements of the sea floor (up to several metres).

Other natural phenomena can cause tsunamis, including landslides and volcanic eruptions. A landslide occurring along the coast could displace large amounts of water, thus generating a tsunami. Underwater landslides can also trigger tsunamis when material from them moves violently, pushing the water in front of them.

Although relatively rare, violent volcanic eruptions can displace large volumes of water and generate highly destructive tsunamis in the vicinity of the source. In August 1883, for example, the largest and most destructive tsunami ever recorded occurred after the explosion and collapse of the Krakatoa Volcano in Indonesia. This explosion generated waves that reached 135 feet in length and destroyed coastal villages along the Sunda Strait on both the Islands of Java and Sumatra, killing 36,417 people.

Tsunamis caused by collisions with extraterrestrial objects such as asteroids and meteorites are extremely rare. Although no tsunami caused by a meteorite or asteroid has been recorded in modern history, scientists say that if these celestial bodies collide with the ocean, they will undoubtedly displace large amounts of water and thus cause a tsunami.

 

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EDITERRANEAN SEA: According to a report published by the UNESCO Intergovernmental Oceanographic Commission (IOC), as reported by the US broadcaster CNN, a tsunami exceeding one metre in height could hit the Mediterranean Sea within the next 30 years.

The Spanish newspaper La Razon has reported that the area most at risk is the Ibn Rushd fault area under the Alboran Sea, which is approximately halfway between the coast of Malaga and North Africa. A tsunami there could be caused by an earthquake that could cause six-metre-high waves that would reach Spain in less than 21 minutes. In the best-case scenario, coastal residents would only have 35 minutes to flee inland, scientists predict.

About 100 tsunamis have occurred in the Mediterranean Sea and its surroundings since the beginning of the 20th century, or about 10 per cent of the total in the world during that period.

Tsunamis in the northeastern Atlantic are less common, although an 8.5-magnitude earthquake occurred in 1755, causing a tsunami that destroyed most of the city of Lisbon in Portugal, Cádiz in Spain, and parts of Morocco, and even reached southwest Cornwall in the UK.

While a tsunami of one metre or even six metres high may not be as large as the 2004 Indian Ocean event that killed more than 230,000 people and displaced 1.7 million others, or the 2011 Japanese tsunami which caused losses estimated at $243 billion, it could cause great damage.

“We do not expect waves of 20 metres, as was the case in Japan, Chile, or Sumatra, but we expect waves of up to a metre or so,” Hélène Hébert, national coordinator of the Tsunami Centre in France (CENALT), told Euronews earlier this year.

“What is very dangerous is not only the high tsunami waves, but also the water flows that lead to floods, which can cause damage to beaches, ports and streets. If the port is small and the waterfront is very low, the tsunami may be more treacherous.”

Pascal Rodel, technical coordinator at the Tsunami Centre in France, told Euronews that “tsunami waves can arrive very quickly, and an earthquake off the coast of Malaga could lead to a tsunami that hits the shore within 21 to 35 minutes.”

“In the western Mediterranean, if an earthquake occurs near Algeria, it will cross the sea within an hour and 15 minutes.”

“Also, although our tsunami waves are not as large as those in the Pacific Ocean, you do not need waves 30 metres high to cause damage and injury, and even a distance of 50 cm can pose a danger to swimmers.”

A number of users of the X platform have shared pictures of water receding from the beaches in more than one Egyptian city, including Port Said and Ras Al-Barr, recently, amid fears of the country being exposed to tsunamis.

The past few days have also witnessed the closure of beaches on the Mediterranean coast in several governorates, including Port Said, Damietta, and Alexandria, in addition to Kafr Al-Sheikh. These closures took place shortly after the occurrence of large waves, while preventing vacationers from going into the sea in areas that witnessed them.

During a meeting last week that brought together Minister of Local Development Manal Awad and the governors of six coastal cities, “developments related to the beaches were followed up due to the receipt of news about expectations of the possibility of earthquakes occurring in countries overlooking the Mediterranean Sea, which may cause waves and currents to rise,” a statement said.

“Severe conditions have occurred on a number of beaches in the coastal governorates, resulting in the taking of the necessary measures for the safety and security of people frequenting those beaches,” it said.

According to the statement, the meeting asked the minister to “coordinate with the rescue agencies working in the governorates to be fully prepared and to take all necessary measures to confront any severe rip currents if they occur, while sending periodic reports immediately and coordinating with officials to take the necessary measures regarding any incidents.”

Vice President of the IOC Amr Hamouda confirmed that the closures were due to weather changes and wind activity, referring to warnings that appeared in the Saudi newspaper Asharq Al-Awsat against vacationers going to some beaches if high waves occur and people being warned against swimming in these areas.

Hamouda said that the Egyptian coasts have not witnessed strong tsunami waves for hundreds of years, however. Such waves were recorded in 365 and 1303 CE as a result of earthquakes with a strength greater than 8 on the Richter Scale. Tsunami waves start from earthquakes whose strength exceeds 7 on the Scale.

The National Institute for Astronomical and Geophysical Research in Egypt commented on the news circulating about the possibility of a tsunami occurring in the Mediterranean Sea. According to its director, Taha Tawfik Rabah, the institute’s seismic monitoring stations, which are located throughout Egypt and are connected to international seismic monitoring stations in the Mediterranean, had not shown any unusual activity.

“Things remain at normal levels, and the stations have not detected any atypical seismic activity,” he said.

 

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ECEDING WAVES: Hisham Al-Askari, professor of remote sensing and earth sciences and systems at Chapman University in the US, told the Al-Hadath Al-Youm TV channel that the ebb and flow of the tides is more likely to be the explanation behind recent alerts.

“A stronger than usual high tide occurred recently due to the Moon’s approach to the Earth, and this led to a more noticeable receding of the sea water from certain beaches,” he said.

Moreover, should an earthquake occur in the Mediterranean threatening to cause a tsunami, this would strike minutes after the earthquake and not wait several days to appear.

“The 2023 earthquake in Turkey included vertical movements of the Earth’s crust, which are the basis for the occurrence of a tsunami, but the horizontal movement reduced them,” Al-Askari said.

Globally, more than 700 million people in low-lying coastal areas and small island developing states are exposed to sea-level hazards, including tsunamis.

An early warning system can only be effective when residents are well informed about tsunami risks and know what to do in the event of an emergency. This means ensuring that vulnerable populations have equal access to relevant information and ways to evacuate.

Inequality creates conditions that increase people’s exposure to disasters such as tsunamis. The groups most affected by such disasters are often the poorest and most vulnerable. Efforts to reduce vulnerability to disasters include addressing issues such as poverty.

Tsunamis are rare, but they can be extremely deadly. Over the past 100 years, 58 tsunamis have killed more than 260,000 people, or an average of 4,600 people per disaster, more than other natural hazards.

The Indian Ocean tsunami in December 2004 led to the largest number of deaths in that period and caused an estimated 227,000 deaths in 14 countries, with Indonesia, Sri Lanka, India and Thailand being the most affected.

Just three weeks later, the international community met in Hyogo in Japan. Governments adopted the 10-year Hyogo Framework for Action, the first comprehensive global agreement on disaster risk reduction.

They also established the Indian Ocean Tsunami Warning and Mitigation System, which includes dozens of monitoring stations recording earthquakes and sea levels and disseminating alerts to national tsunami information centres.

Rapid urbanisation and growing tourism in tsunami-prone areas are also putting more people in harm’s way. This makes risk reduction an essential factor if the world wants to achieve significant reductions in the rate of deaths resulting from disasters, which is the primary goal of the Sendai Framework, a 15-year international agreement adopted in March 2015 as a successor to the Hyogo Framework for Action.

* A version of this article appears in print in the 15 August, 2024 edition of Al-Ahram Weekly