What Caused The Record-Breaking Megatsunami In Greenland?


Robin Andrews

Science & Policy Writer

The wave height, at its peak, was around 100 meters. Dzmitry Melnikau/Shutterstock

One of the largest tsunamis ever recorded – a veritable “mega-tsunami” – took place back on June 17 this year, but it probably passed you by.

This 100-meter-high (328 feet) wave devastated a small Greenlandic community. It was generated by a landslide, which itself was so large that it registered as a 4.1M earthquake on nearby seismographs.


Before we go into the backstory here, a little science lesson is required. Most tsunamis are triggered by earthquakes along specific fault zones called “thrusts”, which involves one side of the fault moving downwards relative to the other. This allows for a vast volume of water to be displaced and triggers a tsunami, which only rises up and causes destruction when it hits land.

The world’s most powerful earthquakes have almost always produced tsunamis, which are invariably more destructive than their paradoxically named, less significant cousins, the so-called “mega-tsunamis.” These are created when a huge object – a piece of a volcano, or a mountain, or even an asteroid – impacts a shallow body of water.

This creates a massive movement of water proportional to the size of the basin it’s in. Apart from an asteroid impact, this creates sudden surges of water that remain quite localized, but whose peak heights dwarf that of most “normal” tsunamis. On a small scale, these beasts are inarguably devastating.

One took place when Thera – now known as Santorini – catastrophically erupted, causing much of the island to fall into the Aegean Sea. The resulting mega-tsunami wiped out most of the Minoan civilization on the island and nearby on Crete.


The same happened in 1792 after Japan’s notoriously deadly Mount Unzen blew itself apart. After the entire southern flank of the volcano fell into the sea, a mega-tsunami emerged that end up killing 15,000 people just across the bay.


Greenland’s megatsunami was no different. Like the tallest tsunami ever created in Alaska’s Lituya Bay (530 meters/1,740 feet high), this one was created when a landslide caused massive chunks of glacier-held rock to fall nearly a kilometer down into the sea. The resulting mega-tsunami wiped out the fishing village of Nuugaatsiaq, as reported by Nature.

The question, then, is what caused the landslide? Unlike the 1958 Lituya Bay event, there wasn’t any tectonic activity at the same time, so an earthquake didn’t cause it. There’s a chance that running melt water loosened the cliff enough to cause it to collapse en masse – and this meltwater is linked to increasingly warm summers.


So is climate change to blame in this specific case? Potentially, but it’s too early to say. One thing’s for sure though: the worse climate change gets, the more often these mega-tsunamis will take place.


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