If you’ve never witnessed a tsunami firsthand, consider yourself very fortunate. But you’ve probably wondered just how much damage a tsunami can cause. How large was the biggest tsunami in history? In this article, we’ll explore the massive tsunami that struck Lituya Bay in Alaska, which is considered the largest tsunami ever recorded. We’ll also look at other significant tsunamis and the science behind these massive waves.
What is a Tsunami?
A tsunami is a massive wave (or more accurately, a series of massive waves) caused by the rapid displacement of water. This is often triggered by geological events such as earthquakes or volcanic eruptions.
Tsunamis can also be caused by landslides or the collapse of glaciers—any event that displaces large amounts of water and generates waves that are longer than typical ocean waves. The word “tsunami” comes from the Japanese, meaning “harbor wave.” 
Are Tsunamis the Same as Tidal Waves?
You may have seen tsunamis in movies, but not all tsunamis strike land like gigantic waves. In fact, they usually resemble rapidly rising tides, which is why they are sometimes referred to as “tidal waves.”
Strictly speaking, this term is inaccurate. Tides are caused by the moon’s gravitational pull, whereas tsunamis are caused by the displacement of water. Nevertheless, the term “tidal wave” is still commonly used, though it can lead to confusion.
The Largest Tsunami Ever Recorded: Lituya Bay (525 Meters)
The Lituya Bay tsunami occurred on July 9, 1958, when a 7.8-magnitude earthquake struck near the Fairweather Fault in Alaska. The earthquake loosened large chunks of rock above Lituya Bay, causing a massive landslide of about 30.6 million cubic meters of debris to plunge into the sea.
Just like throwing a stone into water, the larger the stone, the bigger the splash. This landslide generated a massive displacement of water, creating a wave that reached a height of 525 meters. This wave was high enough to surpass the Empire State Building, dramatically altering the geography of the cold bay.
Fortunately, at the time, the bay and its surroundings had almost no residents. Only three boats encountered the record-breaking tsunami. In the end, two people lost their lives. Although it was a tragic event, the damage was far smaller compared to tsunamis that struck densely populated areas.
Mega Tsunamis
Strictly speaking, the tsunami at Lituya Bay is considered a “mega tsunami.” This term is used to describe events like the one in Lituya Bay, where the displacement of water, usually caused by rocks or ice falling into the water, generates enormous waves. Landslides are a common cause of mega tsunamis.
Why are they different? It seems that when such a collapse happens, the waves produced tend to be higher than those caused by underwater displacement. This may be due to the suddenness of the water displacement.
Five of the Largest Tsunamis in History
While destructive tsunamis are relatively rare, such events have occurred throughout history, though modern technology now allows for more accurate measurement. Here are a few other massive tsunamis, listed by wave height:
1. Mount St. Helens Tsunami (260 Meters)
On May 18, 1980, the eruption of Mount St. Helens triggered a rare mega tsunami. Volcanic activity caused a massive collapse on the northern side of the volcano, leading to a landslide that produced a wave as high as 260 meters. The wave caused extensive damage and affected a wide area.
2. Vaion Dam Tsunami (250 Meters)
On October 9, 1963, a massive landslide occurred above the Vaion Dam in Italy, generating a wave that reached 250 meters. This mega tsunami was partially caused by human factors, as the dam held a large amount of water. When the landslide struck, it generated enough energy to create a tsunami. This event highlighted the destructive power of landslides and the importance of dam design and disaster management.
3. Ice Bay Tsunami (202 Meters)
On October 17, 2015, a massive landslide in Ice Bay, Alaska, caused large rocks to tumble into the water. The sudden movement displaced enough water to create a wave up to 202 meters high. This wave demonstrated the intensity of the landslide and its massive impact on the surrounding environment.
4. Lituya Bay Tsunami of 1936 (150 Meters)
Before the record-breaking tsunami of 1958, Lituya Bay had experienced a tsunami on October 27, 1936. While the cause remains unclear, it is believed to have been triggered by an underwater landslide. The wave reached 150 meters in height, illustrating the powerful effects of this event. The wave’s height was estimated to be between 30 and 76 meters, depending on various measurements and observations.
5. Karat Fjord Tsunami (100 Meters)
On June 17, 2007, a glacier collapse in Karat Fjord, Greenland, triggered a massive geological change that created a wave as high as 100 meters. This powerful wave caused significant damage to the surrounding environment and even affected areas up to 100 kilometers away. The event highlighted the potential impact of glacier melting on geological activity.
The Most Destructive: The Indian Ocean Tsunami (230,000 People Lost)
Today, tsunamis are often evaluated based on the height of the waves, but higher waves don’t necessarily equate to greater destruction. In 2004, an earthquake near Sumatra, Indonesia, triggered the most destructive tsunami in history.
When the first wave struck the surrounding coastlines, it caused massive damage across 14 countries, from India’s east coast to Myanmar’s west coast. The subsequent waves led to a death toll close to 230,000. Although the waves only reached a height of 30 meters, the damage was catastrophic due to the high population density of the affected coastal regions.
