The biggest tsunamis in history
- A tsunami is one of Earth's most powerful and catastrophic natural events, capable of decimating whole islands and communities in minutes.
- Interesting Engineering (IE) round up some of the planet's biggest tsunamis in recorded history.
- While we can never prevent a natural tsunami from occurring, developing efficient alarm systems could help save lives.
A tsunami means 'great harbor wave" in Japanese. It is one of Earth's most powerful and catastrophic natural forces, capable of stretching for thousands of square kilometers across the ocean surface and traveling faster than 800 kilometers per hour. Disturbances to a mass of water, such as an underwater volcanic explosion, earthquake, or landslide, trigger a tsunami.
The height of a tsunami wave above sea level, known as the 'run-up height,' does not substantially increase the deeper it is in an ocean. In fact, tsunami waves are typically only about one meter high in deep water, making their destructive potential somewhat concealed.
Rather, it is only when the waves reach shallower depths, such as near coastlines, that they slow down and can begin to grow - although most tsunamis cause the sea to rise only about 10 feet (3 meters), some waves can reach as high as a skyscraper.
Still, even more, terrifying is a tsunami's wavelength, which determines how far inland it can travel- also known as its 'inundation distance.' As opposed to a large wave with a wavelength of 150 meters caused by a storm, a tsunami could travel more than 620 miles (1,000 kilometers) away and reach up to 0.6 miles (2km) or more inland! As such, some tsunamis can decimate whole islands and communities in a matter of minutes.
Although tsunamis are often referred to as 'tidal waves,' this is slightly misleading. This is because tides- the waves that move through the ocean in response to forces exerted by the moon and sun- have little to do with these immense waves.
Over 100 major tsunamis (those that have caused damage and deaths) have struck this planet's coastlines in the past hundred years, claiming hundreds of thousands of lives and destroying billion of dollars of properties.
Scientists have found startling evidence that even more giant waves, called 'megatsunamis,' have occurred in the past. No coastline on this planet is safe from the threat of megatsunamis.
Here, Interesting Engineering rounds up some of the planet's biggest tsunamis in recorded history.
The tallest tsunami ever recorded
In 1958, the largest- somewhat apocalyptic- tsunami wave ever to be witnessed broke out on a cool July night. After a 7.8 magnitude earthquake 13 miles away, a 1,720-foot tsunami, higher than the Willis Tower in Chicago, loomed over Lituya Bay, a quiet fjord in Alaska (U.S.). The enormous earthquake caused approximately 30.6 million cubic meters of rock to fall 3,000 feet into the Lituya tidewater glacier.
As such, this caused a massive wave of displaced water to rear up, creating a terrifying wave that rushed through Lituya Bay, over La Chaussee Spit, and into the Gulf of Alaska. Five people, including three people on the shore of Khantaak Island at Yakutat Bay's entrance and a couple on a boat in Lituya Bay, were killed. The wave destroyed millions of trees in its wake, the effects of which can be seen today.
Legend has it that there have been previous tsunamis in the Gulf of Alaska. While the enormous mountain ranges coated in snow and ice create a serene landscape on a typical day, the geology of Lituya Bay offers ideal conditions for tsunamis. This explains why it has maintained the tsunami wave record for the last 60 years.
The deadliest human-made tsunami disaster ever
On October 9, 1963, the top of Monte Toc, which sits on the border of Veneto and Friuli Venezia Giulia in Italy, gave way. This released 260 million cubic meters of rock into Vajont Dam's reservoir- one of the largest dams in the world at the time.
A massive wave of water with a volume of at least 50 million cubic meters and 771 feet high was created from the landslide. While the dam itself did not suffer any severe damage, flooding in the valley in the dead of night led to the destruction of several villages. This killed nearly 2,000 people, most of whom were sleeping at the time.
Longarone, a mountain village with primarily residential and commercial buildings, and a popular tourist destination, was destroyed by the giant wave.
Still, locals had been terrified that Monte Toc would one day collapse years before it did. Some had witnessed small landslides from as early as two years after the dam's construction in 1958. Builders and managers ignored soil conservation requirements, filling the reservoir far beyond safety regulations.
The Mount St Helens Tsunami
On May 18, 1980, after a quiet period of 123 years, a series of earthquakes were followed by an eruption of Mt. St. Helens. Its north flank collapsed, causing one of the largest landslides in recorded history. The landslide displaced an enormous amount of water, resulting in an 820-foot tsunami- the third-largest in history.
The tsunami slammed into the side of Mount Margaret before crashing into the basin below. Still, this was enough to cause havoc along the Pacific Northwest coastline, including Washington, Oregon, and British Columbia, where 14 people were killed and causing more than $1 billion in damage.
Tsunami of the Icy Bay, Alaska
On October 17, 2015, a historic megatsunami struck the remote Alaskan fjord of Icy Bay. The 633-foot wave removed eight square miles of forest from Wrangell St.-Elias National Park and Preserve. It was triggered by 180 million tons of rock sliding into Taan Fiord, an arm of the Icy Bay glacier.
Fortunately, no humans were in the area where the event occurred. Icy Bay, like Lituya Bay, has dramatically steep walls carved out by a retreating glacier, significantly contributing to the tsunami's ferocity.
Tsunami of the Ambon Island, Indonesia
The first megatsunami to be meticulously documented in Indonesia remains one of the most biggest tsunamis ever recorded. An earthquake struck the Maluku Islands in the Banda Sea on February 17, 1674.
The earthquake caused a massive wave to crash into Ambon Island, killing over 2000 people. The Hitu Peninsula's coastal hills were submerged when the water reached them, indicating that the tsunami's peak height was around 328 feet.
The largest Tsunami to hit Greenland
Tsunamis rarely hit Greenland, but in 2017 it was hit by one of the largest waves ever recorded there. On June 2017, a landslide on Karrat Fjord sent a 295-foot-high wall of water into the fishing village of Nuugaatsiaq. The megatsunami killed four individuals and destroyed 11 buildings.
The event, according to experts, was caused by a warming climate defrosting the glacial landscape. The mountains near Karrat Fjord continue to be unstable, and a future landslide-caused tsunami could be on the horizon for Greenland.
A Megatsunami of the Future, Canary Islands
La Palma, an island in the Canaries, has been the source of much talk as an ideal location for a landslide-induced megatsunami. Some scientists believe a future eruption of the island's Cumbre Vieja volcano may cause its western flank to collapse.
If that happens, a massive amount of rock, weighing up to 500,000 million tonnes, would fall into the Atlantic Ocean.
Experts have modeled the potential consequences of such a collapse in Switzerland. According to their model, it could produce a wave large enough to engulf every port on the east coast of the United States. They compare this future catastrophic tsunami event to one that occurred 120,000 years ago.
The most damaging tsunami to infrastructure
The earthquake and tsunami that struck the Tohoku region in Japan on March 11, 2011, caused damages to infrastructure far greater than any other tsunami in modern history.
An earthquake with a magnitude of 9.0 was followed by waves that rose as high as 132 feet. Over 15,500 persons lost their lives in this catastrophe, which also left over 450,000 people homeless.
The tsunami also caused a level seven nuclear meltdown and the leakage of radioactive materials at the Fukushima Daiichi power facility, with material losses estimated to be $300 billion.
The most deadliest tsunami in the 21st century
On the morning of December 26, 2004, an underwater 9.1 magnitude earthquake triggered a massive tsunami that raced across the Indian Ocean.
In just a few hours, the tsunami affected 11 nations, after first striking Indonesia, including Thailand, Sri Lanka, India, and South Africa. This tsunami has the highest recorded death toll at nearly 230,000, with some waves rising over 100 feet.
There were no adequate plans or communication methods for this kind of disaster in the Indian Ocean before the 2004 tsunami. Since then, researchers and governments have changed how research is conducted and how preparations are made to understand tsunamis better and put early warning systems in place.
While we can never prevent a natural tsunami from occurring, developing effective alarm systems that sense when one is underway could help people evacuate to higher ground in time and, ultimately, save lives.
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