How does a tsunami originate after an earthquake like the Kamchatka earthquake?

Madrid, July 30 (EFE).- The depth, magnitude of 8.8, and fault characteristics of the earthquake off Russia's Kamchatka Peninsula combined to generate a tsunami that has already reached several countries, including the United States.

The first waves of the tsunami hit Hawaii, and the alert forces the evacuation of Fukushima.

The earthquake off Russia's Kamchatka Peninsula, the eighth largest ever recorded in the world at 8.8, triggered a tsunami, which has already impacted several countries due to the vertical movement of the fault.

What is a tsunami?

A tsunami is a sudden movement of sea water, which can occur as a result of a meteorite falling, avalanches and underwater volcanic eruptions or when the epicenter of an earthquake is located on the seabed, as has been the case here, according to the National Geographic Institute (IGN).

This causes ripples to propagate through the water and create giant waves.

How did the Kamchatka disaster happen?

As explained in its X account by the Institute of Geosciences (IGEO), a joint center dependent on the Spanish National Research Council (CSIC) and the Complutense University of Madrid, for a tsunami to occur after an earthquake, the fault must have a vertical movement.

In the case of Kamchatka, it occurred at a depth of 20 kilometers due to a "compressive and expected" movement because it is in the Pacific subduction zone against the North American plate.

In fact, for a tsunami to occur, the earthquake on the seafloor must be of great magnitude, as it must move abruptly vertically, thus pushing the column of water above it.

From a wave to a wall of water

The head of the IGN area, José Benito Bravo Monge, explained to EFE how these waves behave in the open sea and when they reach the coast.

"In the deep ocean, tsunami waves are barely perceptible. They can be only a few centimeters high and go unnoticed even by ships. But as they approach the coast, the depth of the sea decreases and the speed of the waves slows," he explained.

This sudden braking causes waves to overtake each other, accumulating like a chain reaction: "They pile up on top of each other and gain height. What was once a nearly invisible wave on the high seas can transform into a wall of water several meters high when it hits land. That's what causes the destruction."

In this context, he emphasized that the danger of a tsunami depends not only on its magnitude, but also on the location where it hits, as the real risk is determined by whether it hits inhabited areas or infrastructure. If it strikes an uninhabited coast, the impact may be less severe.

International collaboration and alert system

The IGN actively collaborates with international organizations to share data and improve the location and analysis of seismic events, the expert noted, adding that "the more data we have and the more seismic networks involved, the more precise we will be in determining where and how the earthquake occurred."

Regarding preparedness for these types of phenomena, the expert emphasized the importance of early warning systems, especially in the case of tsunamis. "Although we cannot predict an earthquake, we can anticipate some of its most dangerous consequences. That's why it's essential to have good infrastructure, resilient buildings, and effective warning systems," he stressed.