The tsunami triggered by the 24 June 2026 Venezuela earthquakes: tectonic context and tsunami modelling

Imagine the ocean floor not as a flat, silent stage, but as a giant, shifting puzzle of tectonic plates. Sometimes, these plates crash into each other like colliding cars, pushing the ground up and down. Other times, they scrape past one another like two people trying to squeeze through a narrow doorway, sliding horizontally. For a long time, scientists thought only the "crashing" earthquakes could shake the water enough to create a tsunami—a massive, dangerous wave. They believed the "sliding" kind was too smooth to splash the ocean. But the Caribbean Sea is a busy place where plates grind together, and this paper explores a fascinating twist: can a sliding earthquake still kick up a wave? It turns out, if the slide happens right next to a steep underwater cliff or a deep, bowl-shaped basin, it can act like a spoon stirring a cup of coffee, creating a splash that travels across the sea. Understanding this is crucial because millions of people live along these coastlines, and knowing exactly how these waves start helps us build better warnings to keep everyone safe.

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The Big Splash in Venezuela

On a Wednesday in late June 2026, the ground shook violently in Venezuela. Two earthquakes, one slightly smaller than the other, hit just 39 seconds apart. They were "strike-slip" events, meaning the ground mostly slid sideways rather than buckling up and down. But here's the kicker: the ocean didn't just ripple; it roared. A tsunami was born.

While the Caribbean Sea doesn't have a perfect network of sensors (it's a bit like trying to listen to a whisper in a crowded room with only a few microphones), the wave was spotted. In the town of Choroní, locals filmed the water pulling back dramatically, then crashing onto the seawall. The wave was estimated to be about 1.3 meters from its highest point to its lowest—roughly the height of a tall teenager. Far away, in Puerto Rico and the Virgin Islands, sensitive tide gauges picked up the wave, though it had shrunk to a more modest 10 centimeters by the time it arrived.

The Detective Work: Simulating the Source

The authors of this paper wanted to know: How exactly did a sideways-shaking earthquake create a wave? To find out, they used a supercomputer model called COMCOT. Think of this model as a digital sandbox where they could replay the earthquake over and over, changing the rules to see what happened.

They tested five different "source scenarios" (five different ideas of how the fault broke):

1. The Simple Slides: They tried three versions where the fault slid evenly, like a giant block of ice moving across a table.
2. The Complex Breaks: They tried two versions based on real, messy data (called Finite-Fault Models) where the slip wasn't even. Some parts of the fault moved a lot, others moved a little, creating a jagged, uneven motion.

What the Computer Told Us

The results were a clear lesson in complexity. The "Simple Slide" models were total failures. They predicted waves that were way too small to explain what people saw in Choroní or what the sensors in Puerto Rico recorded. It was like trying to explain a tsunami with a gentle ripple.

However, the "Complex Break" models were much better. Specifically, the model based on USGS data (FFM USGS) did a great job of matching the real-world observations. It successfully predicted when the waves would arrive and how big they would be at distant locations like Puerto Rico. This suggests that the earthquake didn't just slide evenly; it likely broke in a complex, uneven way that pushed the water more effectively.

The Mystery of the Missing Wave

But there was a catch. Even the best computer model couldn't fully explain the huge wave seen in Choroní. The simulations showed waves reaching about 1 meter in some spots, but the video evidence suggested the water was moving incredibly fast—maybe even faster than 3 meters per second locally. The computer models, which used a grid resolution of about 460 meters (roughly five football fields wide), simply couldn't see the tiny, sharp details of the coastline that might have amplified the wave.

The authors suggest a few reasons for this gap:

• The Bay Effect: The wave hit a semi-enclosed bay (Choroní). Just like sound echoes in a bathroom, the shape of the bay might have trapped the wave energy and made it bounce higher.
• The Landslide Guess: The authors suggest a possibility that the earthquake might have triggered a submarine landslide—a chunk of the ocean floor sliding down a steep slope. This is a strong idea because landslides are known to create very directional, powerful waves, and the area off Venezuela has very steep underwater slopes. If a landslide happened, it would explain why the wave was so strong near the source but weaker elsewhere.

The Takeaway

This paper confirms that even sideways-sliding earthquakes can generate dangerous tsunamis in the Caribbean, especially when they happen near steep underwater slopes or deep basins. The best way to understand these events is to use complex, messy models rather than simple, smooth ones.

However, the story isn't fully solved. The difference between the computer's prediction and the real video footage suggests that something else might be happening—perhaps a landslide or local coastal effects that our current maps and sensors are too blurry to see. The authors conclude that we need better tools, like more sensors along the Venezuelan coast and perhaps even smart cables on the ocean floor, to catch these waves in the act next time. Until then, we know that the "sliding" earthquakes in this region are not as harmless as we once thought, and they deserve our full attention.