The Tallest Tsunami On Record Hit Alaska With A 524-Meter Wave In 1958

It’s difficult to fathom a wave taller than the Empire State Building, but a tsunami that big struck Alaska in 1958. The megatsunami remains the tallest ever recorded, but it wasn’t the most destructive as it hit Lituya Bay, a remote spot along the Gulf of Alaska where not many people live.

Five people are believed to have died that day. Three were standing on the beach at the mouth of the Yakutat Bay when it subsided 30 meters (100 feet) below sea level, explains the Western States Seismic Policy Council (WSSPC), and two people who had gone fishing when the wave struck were never seen again.

Some survivors actually managed to ride out the apocalyptic waves in their fishing vessels. According to the NASA Earth Observatory, one fisherman explained the way his ship was “lofted over a forested spit on the crest of one wave and looking down at trees below.”

The megatsunami was triggered by a huge chunk of rock that was 732 meters (2,400 feet) by 914 meters (3,000 feet), and 91 meters (300 feet) thick, that plunged 610 meters (2,000 feet) from the northern wall of the inlet into the water. The size and severity of the rockfall has been compared to an asteroid hitting the water, and the shape of the fjord is partly to blame for the subsequent chaos.

    

Lituya Bay is a narrow fjord with a U-shaped seabed. You can imagine the movement of water within it by considering what would happen were you to drop a bowling ball into a bath: The impact of the rockfall caused a similar back-and-forth of sloshing water that meant the bay was struck by multiple enormous waves, the biggest of which was taller than the Empire State Building at 524 meters (1,720 feet) high.

The rockfall was caused by an earthquake, and the WSSPC concluded that while there’s little that could have been done to prevent the five deaths that day, we can learn from the sheer enormity of what happened.

“The earthquake was so strong, and the tsunami came so quickly, that there was not time to get to a safe place,” they said. “It does, however, highlight the importance of documenting such events for posterity, and to consider such extreme events when making development decisions for coastal areas in areas with high seismicity or vulnerability to tsunamis.”

The Lituya Bay tsunami wave had a run-up height compared to the Burj Khalifa, Empire State Building, and Eiffel Tower.
Image credit: Phoenix CZE – Own work, CC BY-SA 4.0, via Wikimedia commons

Its effects can still be seen today, even from space, represented as a barrier of treeline where the foliage is much younger than that which sits above it. The ferocity of the tsunami ripped trees up by their roots, making conditions even more dangerous for the two boats that managed to ride out the waves.

If you’re in the mood for calmer waters, check out the largest lake that ever existed.

[H/T: Indy100]

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