Sep 20, 2026
There is something deeply unsettling about seeing the sea suddenly disappear.
The waterline recedes, exposing rocks and sandy areas that are normally submerged beneath the Mediterranean, and for a few minutes, the coastline appears to have changed shape. Then, the water quickly returns and can surge onto beaches, promenades, and even nearby streets.
That is precisely what happened in different parts of the Costa Blanca at the end of August 2026. And although the image may be reminiscent of stories about tsunamis, in these specific episodes it was not an underwater earthquake that caused the movement of the sea.
It was another phenomenon, much less known: a meteotsunami .
When the sea changes location in a matter of minutes
On August 24, 2026, abrupt fluctuations in sea level occurred at several points along the Valencian coast. Santa Pola, Xàbia, Dénia, and Gandia were among the towns where the phenomenon was particularly visible.
In Santa Pola, the sea receded, exposing areas that are normally submerged. Shortly afterward, it surged back toward the coast, reaching areas near Blasco Ibáñez Avenue and even forcing temporary road closures in some places.
In Gandia, the tide gauge readings from the State Ports Authority showed an extraordinarily rapid variation: about 33.6 centimeters above the reference level and, just six minutes later, 37.1 centimeters below . That is, an oscillation of around 70 centimeters in a very short time.
The phenomenon was also observed in Torrevieja and Orihuela Costa , where oscillations of approximately 30–40 centimeters were recorded, especially visible in the Playa de los Locos area.
The State Meteorological Agency (AEMET) explained that it was not a tsunami caused by an earthquake, but a phenomenon related to atmospheric gravity waves , pressure changes and the response of the water mass itself.
And the most interesting thing is that it wasn't the first time something like this had happened on this coast.
The Costa Blanca has already experienced similar episodes.
In July 2017, abrupt sea level movements were recorded at several points along the Alicante coast: Torrevieja, Santa Pola, El Campello and the Marina of Elche, among others.
In Torrevieja, at Playa de los Locos, oscillations of about 30–40 centimeters were observed for approximately an hour and a half.
Four years later, in August 2021, Santa Pola experienced another, much more dramatic event. The sea level rose sharply in the port area, affecting moored boats, beaches, and promenades. Water even flooded some streets.
AEMET officially classified that episode as a rissaga or meteotsunami .
And at the end of August 2026 it happened again.
On August 28, Torrevieja and Guardamar del Segura also activated the red flag and prohibited swimming due to the risk associated with new rapid oscillations in sea level and the currents that can occur during these episodes.
In some areas of Orihuela Costa and Campoamor, witnesses described how the sea receded several meters before returning with force.
There had been no major underwater earthquake.
So, what exactly is a meteotsunami?
The word can be misleading. A meteotsunami doesn't originate at the bottom of the sea, but in the atmosphere.
Certain weather conditions can produce rapid changes in atmospheric pressure and pressure waves that travel across the Mediterranean . When these disturbances coincide with specific sea and coastal conditions, they can generate considerable fluctuations in water level.
The effect is similar to that of a tsunami: the sea can recede quickly and then return towards the coast.
The fundamental difference lies in the origin.
A classic tsunami typically begins with an underwater earthquake that vertically displaces a large volume of water . It can also be triggered by an underwater landslide, a volcanic eruption, or other significant movements of the seabed.
In contrast, in a meteotsunami the energy comes from the atmosphere.
In the Mediterranean, moreover, conditions can amplify these small disturbances. The shape of certain bays, ports, and coastal platforms can act as a kind of resonator, increasing the movement of the water.
That's why an atmospheric change that initially seems small can end up producing a very visible oscillation on the coast.
But real tsunamis are also possible in the Mediterranean
The fact that recent episodes on the Costa Blanca have been meteotsunamis does not mean that a tsunami caused by an earthquake is impossible in the Mediterranean.
Spain has a much more significant seismic and tsunamigenic history than is usually imagined.
The most recent example is May 21, 2003 , when an earthquake of approximately magnitude 6.8 off the coast of Algeria generated a tsunami that swept across the western Mediterranean.
The phenomenon was recorded by tide gauges at various locations in Spain and other Mediterranean countries. In Spain, maximum wave heights of nearly 2 meters were recorded, and the sea movement was particularly significant in the Balearic Islands, although the tsunami signal was detected at numerous points throughout the western Mediterranean.
According to the National Geographic Institute, it was the last tsunami to affect Spain .
Spain even has specific settings for this coast.
The State Civil Protection Plan for the Risk of Tsunamis identifies different zones and faults capable of generating significant sea movements.
Among them are structures related to the southeast of the peninsula, such as the faults of Crevillente, Santa Pola and La Marina .
The studies used for emergency planning consider scenarios in which certain coastal areas could experience sea level rises exceeding one meter. In some scenarios for the northern coast of Murcia, for example, increases of around two meters have been calculated in association with a possible rupture in the La Marina fault, with arrival times on the order of half an hour.
That does not mean a tsunami will occur, nor is it a prediction.
These are planning scenarios used to study how to respond to a hypothetical emergency.
Since 2015, Spain has had a National Tsunami Warning System , coordinated by the National Geographic Institute. The seismic network and tide gauges allow for the detection of potentially dangerous earthquakes and real-time monitoring of sea level variations.
Why does the sea recede before a wave?
This is perhaps the most well-known image of a tsunami and, at the same time, one of the most dangerous.
When a tsunami reaches a coast, the first wave is not always a rise in sea level. Depending on how the seabed is displaced and the direction in which the wave propagates, the water may recede first .
The problem is that this retreat can be fascinating.
The beach seems to suddenly expand. Rocks, sand, objects, and areas of the seabed that are normally unseen appear. It's easy to get closer to look or even take pictures.
But doing so can be extremely dangerous.
The returning water can travel at high speed and sweep away people, vehicles, and objects. Furthermore, after the first wave, others may follow, and the first one won't necessarily be the largest.
That is why the National Geographic Institute recommends that if a person is on the coast and observes an abnormal and sudden retreat or rise of the sea, they should immediately move away from the shore and head towards a higher area or inland , especially if they have previously felt an earthquake.
A Mediterranean that doesn't always behave as we expect
Perhaps the most interesting thing about these episodes is not thinking about a huge wave reaching the Costa Blanca, but understanding the extent to which the Mediterranean can change its behavior in a matter of minutes.
We are used to thinking of the sea as a constant presence: it rises and falls slowly with the tides, responds to the wind and storms, and returns every day to occupy practically the same place.
But beneath that calm appearance lies a system that is extremely sensitive to the atmosphere, the shape of the coast, pressure, wind, seismic movements, and the very configuration of the seabed.
The episodes of 2017, 2021 and 2026 have demonstrated this in familiar places such as Torrevieja, Santa Pola, Xàbia or Guardamar.
Sometimes the sea doesn't need an earthquake to surprise us.
All it takes is an atmospheric disturbance, a certain coastal configuration, and a few minutes.
And when the Mediterranean suddenly decides to retreat, the most important thing is not to approach and see how far it has gone.
It is understanding that, at that moment, the sea is warning that something has changed.