Mount Etna’s Underwater Flank: A Looming Tsunami Threat

Mount Etna, located on the east coast of Sicily, is a majestic yet perilous giant that has captivated the world with its beauty and ferocity.

However, recent scientific findings have unveiled a chilling reality: the volcano’s southeastern flank is undergoing rapid movement, raising concerns about the potential for a catastrophic underwater landslide that could trigger a tsunami.

This mass, consisting of approximately 25 cubic kilometers of volcanic rock, is shifting at an alarming pace, four times faster than previously recorded.

What is causing this sudden acceleration?

The answer lies not in magma but in the force of gravity itself.

As this colossal block of rock inches closer to the sea, scientists are drawing parallels to a similar event that occurred around 8,000 years ago, when a section of Mount Etna collapsed into the Mediterranean, generating a tsunami that wreaked havoc on coastal communities.

Deep beneath the Ionian Sea lies a hidden world, a vast underwater landscape that holds the key to understanding the current threat.

The geological records reveal layers of disturbed sediment and ancient landslide deposits, remnants of past collapses that serve as ominous reminders of nature’s power.

These deposits tell a story of instability, where the balance of the mountain was lost, leading to violent interactions with the sea.

Modern research teams are employing advanced techniques, such as deep-sea cores and seismic imaging, to investigate these underwater scars and assess the risk posed by the shifting flank.

The sheer scale of the unstable mass has prompted intense scrutiny from scientists and researchers.

While the movement has been measured in centimeters per year, the potential for a sudden collapse remains.

The teams from Italy’s National Institute of Geophysics and Volcanology, along with international collaborators, are meticulously mapping and monitoring the area, understanding that if a block of this size were to break free, it could displace enough water to generate tsunami waves that would radiate across the Mediterranean.

The evidence of past collapses is clear, preserved in the sediments that blanket the seafloor.

These geological markers indicate moments in history when the stability of the mountain was compromised, leading to catastrophic events that reshaped coastlines.

The current situation is particularly alarming, as recent monitoring has shown a dramatic increase in the rate of movement along the underwater flank.

In May 2017, sensors recorded a staggering shift of over 4 centimeters in just eight days, a rate that far exceeds the background motion previously observed.

This acceleration is not just a fleeting disturbance; it signals a system under increasing stress.

Gravity is the primary driver here, pulling the massive underwater slopes downward, while the steepness of the seafloor and the weight of the overlying rock contribute to the instability.

Unlike traditional volcanic eruptions driven by magma pressure, this phenomenon is rooted in the relentless pull of gravity, creating a natural slide that could have catastrophic consequences.

The situation is further complicated by recent volcanic activity detected beneath the eastern flank of Etna.

In early 2025, new magma intrusions were identified, leading to fresh fractures and openings in the mountain.

While these intrusions do not directly push the underwater slope, they add internal pressure that can exacerbate the existing instability.

The interplay between gravity and volcanic activity creates a precarious situation where small changes can escalate into significant hazards.

Research has revealed that the most rapid deformation occurs far from the summit, along offshore faults that lie beneath more than 1,000 meters of water.

During the 2017 slip event, the underwater flank moved as much as the entire onshore system combined, confirming that the instability is deeply rooted below the surface.

This discovery has overturned decades of assumptions about Etna’s behavior, shifting the focus from magma-driven processes to gravity-controlled dynamics that can accelerate with little warning.

The challenge for scientists is not only to measure these changes but to comprehend how gravity, fault structure, and volcanic activity work together to set the pace of instability.

As the rates of movement continue to exceed historical norms, the urgency to monitor and interpret every shift has become paramount.

Inside the monitoring center, teams are working tirelessly to analyze the data streaming in from a network of sensors deployed on the seafloor.

These devices, capable of detecting minute shifts with incredible precision, play a crucial role in tracking the movement of Mount Etna’s underwater flank in real time.

In the wake of the 2017 slip event, the deployment of acoustic transponders on the seafloor has revolutionized how scientists monitor the volcano’s behavior.

With these sensors anchored at depths of around 1,200 meters, researchers can capture every subtle shift, providing invaluable insights into the ongoing changes beneath the waves.

The data collected has revealed a consistent pattern of deformation, with movement increasing as one approaches the submerged edge.

This gradient reinforces the understanding that gravity, not magma pressure, is the primary force at play.

As scientists continue to analyze the data, they remain acutely aware of the implications of a potential collapse.

With over three million people living within the Mediterranean’s tsunami impact zone, the stakes are incredibly high.

Coastal towns like Katana, Syracuse, and numerous smaller villages are directly in the line of fire, making the need for effective emergency planning and response all the more critical.

Local officials are grappling with the realities of evacuation logistics, knowing that the window for action may be as short as 15 to 20 minutes between the first signs of a collapse and the arrival of a tsunami.

This challenging landscape compels emergency managers to develop comprehensive evacuation plans, ensuring that residents and visitors are informed and prepared to respond swiftly.

The task is daunting, as many coastal roads run parallel to the sea, limiting options for rapid escape.

Moreover, the complexities of coordinating responses across borders add another layer of difficulty.

As the Mediterranean is home to multiple nations, the need for a unified approach to disaster response has never been more pressing.

In response to this urgent threat, government officials and scientists from Italy, Greece, and North Africa are collaborating to create protocols that ensure alerts triggered by Etna’s monitoring network reach every coastal authority without delay.

This requires a sophisticated system that integrates various technologies and procedures, allowing for seamless communication during a crisis.

The goal is clear: to save lives by ensuring that when the warning comes, the response is immediate and coordinated.

As climate change and rising populations exacerbate the risks, the urgency for preparedness continues to grow.

Nature operates on its own timeline, and the responsibility to act before disaster strikes falls on the shoulders of those in power.

The threat posed by Mount Etna is not merely theoretical; it is a pressing reality that demands immediate attention and action.