What Would Happen if Santorini Erupted Today? A VEI 7 Simulation

THE DAY THE SKY TURNED BLACK: THE CATASTROPHIC ERUPTION OF SANTORINI

Prelude to Disaster

The signs had been there for months, even years.

Santorini, the jewel of the Aegean, a crescent-shaped paradise of whitewashed homes and sapphire seas, had begun to change. It started with tremors—small at first, barely perceptible. But by the end of the year, they became impossible to ignore. In Athens, seismologists warned of something massive shifting beneath the volcanic island.

In the weeks leading up to the eruption, the island’s caldera floor swelled. Villages on the rim cracked and buckled as the earth heaved upward. Streets split open, revealing fissures that vented steam and sulfurous gas. Fishermen reported boiling water and strange gases bubbling up from the deep, and some witnessed dead fish floating in unnatural numbers near the caldera rim. Tourists still came, drawn by curiosity, oblivious to the dread settling over those who had lived here for generations.

Before magma ever reached the surface, the first signs of violent activity came in the form of phreatic eruptions—explosions caused by the interaction of rising heat with underground water. These eruptions occur when groundwater or trapped seawater is suddenly superheated by the intense heat from the rising magma below, but without direct magma-water interaction. Instead of mixing with molten rock, the water is heated through conduction and rising gases, causing it to expand into steam almost instantly. The rapid expansion generates immense pressure, fracturing the rock above and launching it skyward in violent blasts. These early explosions serve as warnings of what is to come, destabilizing the landscape and creating new pathways for magma to eventually escape.

Then came the first phreatic explosions—sharp, thunderous cracks from the depths of the earth, as superheated groundwater flashed into steam, blasting apart the fractured rock above the magma chamber. Columns of steam and ash rose from the volcanic vents at Nea Kameni, signaling the onset of a volatile precursor phase. The sky above the island darkened, as these initial steam-driven eruptions sent clouds of ash and pulverized rock over the caldera’s rim, lightly dusting buildings. These explosions were a warning—though they contained little fresh magma, they signified that the hydrothermal system within the volcano was destabilizing. The lack of direct contact between magma and water at this stage meant that the eruptions were driven purely by steam pressure, rather than the more explosive reactions that would occur later when magma finally breached the surface. The venting of steam, sulfur dioxide, and pulverized rock suggested that the magma was now dangerously close to the surface, increasing the risk of a full-scale magmatic eruption. Scientists warned that these phreatic blasts were only the beginning. As cracks widened and pressure continued to build, it was only a matter of time before fresh magma reached the surface, transitioning the eruption into a full-scale Plinian event. Yet, authorities hesitated to issue full-scale evacuation orders, fearing unnecessary panic.

Gas emissions increased drastically, with plumes of sulfur dioxide reaching unprecedented levels. Earthquakes grew stronger, their epicenters shifting closer to the island’s heart. Wildlife began to disappear, birds taking to the skies and fleeing in all directions. In the days before the eruption, an ominous silence fell over Santorini—no birds sang, the winds stilled, and the once-busy tourist spots became ghost towns.

The final warning came in the form of harmonic tremors—deep, rhythmic shaking, a sign that magma was on the move. Those monitoring the volcano knew what was coming, but there was nothing left to do. Roads were already choked with people trying to flee, but ferry services struggled to keep up with the demand. As night fell, the island lay eerily still, its fate sealed by the pressure building beneath it.

Then, the earth roared.

The Beginning of the End

On a warm summer morning, just before dawn, the island shook violently—an earthquake larger than any before it. It toppled buildings and sent landslides crashing down the caldera walls. The sea receded from the cliffs, as if the island itself was gasping. Then, in one violent instant, the sky was torn apart.

The phreatomagmatic phase began as magma finally breached the surface and made direct contact with seawater that had infiltrated the fractured landscape. The reaction was immediate and cataclysmic—vast explosions of steam and molten rock tore through the caldera, sending towering jets of ash, gas, and fragmented lava high into the sky. The sound was deafening, a concussive blast that shattered what little remained of Santorini’s structures. Torrents of scalding water mixed with pyroclastic material, generating surges that raced outward, engulfing the island in superheated slurries of ash, pumice, and gas.

The violence of this stage far surpassed the earlier phreatic explosions. Unlike the steam-driven eruptions that had come before, these blasts contained fresh magma, increasing their intensity and destruction. The mingling of water and magma created an unrelenting series of rapid, pulverizing explosions, as each surge of seawater was instantly vaporized upon contact with the magma. The resulting pressure waves sent shockwaves through the Aegean, felt even on the distant shores of Crete and beyond. What had been a towering ash column now became a chaotic, expanding maelstrom of incandescent rock and steam, as the eruption transitioned fully into its Plinian climax.

A colossal plinian eruption launched a jet of incandescent ash and gas 40 kilometers into the sky. The detonation was heard as far away as Italy.

Within minutes, the entire island was cloaked in darkness as ash began falling in suffocating torrents. The sun vanished, replaced by a thick, roiling cloud of volcanic debris. Tourists and residents alike ran for cover, seeking shelter in basements, caves, and makeshift refuges. The air grew thick, unbreathable. Lightning streaked through the volcanic plume, flashing like an omen of destruction as pyroclastic surges—searing avalanches of gas, ash, and rock—began their deadly descent toward the sea.

By noon, Santorini was unrecognizable. Ash had buried buildings, and entire neighborhoods had been set aflame by the intense heat. Livestock lay dead in the streets, and those caught in the open perished within seconds, their lungs seared from the superheated air. The air was so thick with dust and sulfur that daylight vanished entirely. A howling, suffocating darkness blanketed the land.

The weight of falling ash collapsed rooftops, burying survivors who had sought shelter indoors. Rescue teams, desperate to reach those trapped beneath the rubble, found themselves working blind in a suffocating, toxic atmosphere. The island, once a lively paradise, had become a vision of hell.

The ash column continued to rise, propelled first by the sheer force of the eruption, sending debris in all directions, including westward over mainland Greece. However, as the hours passed, the prevailing trade winds took control, driving the thick volcanic plume eastward toward Turkey and beyond, blanketing the region in darkness. This immense cloud of ash stretched for hundreds of kilometers, turning day into night and raining fine volcanic particles over vast swathes of land. The land trembled as fountains of lava shot into the air. Fiery debris rained down on neighboring islands, igniting wildfires that raged uncontrollably. Even those who had fled Santorini were not safe. Ships in the Aegean found themselves coated in a layer of volcanic ash, choking their engines and rendering them helpless against the rough seas.

For hours, the volcano continued to expel vast amounts of ash and pumice, burying the island under a thick, smothering layer of debris. The eruption did not stop in a single explosion—it persisted, the sky darkening with each successive burst of volcanic material. The plinian phase was relentless, the column of ash reaching the stratosphere, where winds carried the fine particles across continents. Across the Mediterranean, people awoke to find their cities coated in a thin layer of ash, the air thick with a sulfuric haze.

With each eruption pulse, violent shockwaves rippled outward, breaking windows hundreds of kilometers away. The unrelenting roar of the volcano was deafening, an ever-present sound of destruction that echoed across the Aegean. Those who had not yet succumbed to the initial phases of the eruption now faced a terrifying reality—escape was no longer a mere choice; it was a necessity. Every breath was a struggle, the air thick with scorching ash, reducing visibility to nearly nothing. Entire towns and villages were abandoned as survivors fled toward the coastline, hoping for a chance to escape before the island met its final fate. Volcanic bombs—glowing chunks of molten rock—fell like meteorites, setting the land ablaze. The ground quaked continuously, a reminder that the island was being reshaped by forces beyond human control. Santorini itself was disappearing beneath its own destruction, its once-proud cliffs eroding beneath the unyielding downpour of ash and rock. Those who managed to reach the shores found themselves at the mercy of an unforgiving sea. Boats overloaded with desperate souls attempted to navigate through waters that were now boiling with submerged lava fragments, the heat rising in waves from the ocean’s surface. Some vessels capsized under the weight of their passengers, others were swallowed by the relentless waves stirred by constant seismic activity. The volcano, still spewing fire into the heavens, continued its merciless campaign, each eruption bringing the inevitable collapse of the island closer. If life still remained at this point, now was the time to escape before the next step took place.

Hell Unleashed

The second phase began several days later, as the eruption showed no signs of stopping. The relentless explosions had gradually weakened the very foundation of the island. The land trembled constantly, with deep fractures appearing along the caldera’s edges. Great fissures split open the ground, some venting steam while others spewed molten rock in fiery cascades. The coastline was reshaped by the day, as landslides and cliff collapses sent plumes of dust and debris into the churning sea. It became evident that the island was on the brink of an irreversible transformation. The island could no longer hold back the fury below. As the eruption continued, vast amounts of magma were ejected, leaving behind a void beneath the surface. Over the following days, the weakened structure of the island could no longer support itself. Then, as if the earth itself could bear no more, a final, thunderous detonation signaled the collapse. With a deafening roar, the entire center of Santorini collapsed inward. The sea rushed in, consuming what was left of the land, creating a massive vacuum that sent shockwaves through the region. The water boiled violently upon contact with the still-molten rock, sending up towering columns of steam that mixed with the already darkened sky. Entire sections of the island crumbled into the abyss, leaving behind a vast, sunken caldera where a thriving landscape once stood., triggering one of the most violent geological events in recorded history. The ancient magma chamber, now empty, gave way in an instant, swallowing towns and villages as the caldera caved in.

This triggered the most violent pyroclastic flows yet—immense walls of superheated gas and ash moving faster than a jet plane, obliterating everything in their path. Nowhere on Santorini was safe. Those who had survived the first phase had only seconds to react. As the caldera collapsed, a massive vacuum was created, causing the surrounding seawater to rush inward with immense force. This sudden displacement triggered a titanic tsunami that raced outward in all directions. Pyroclastic flows cascading into the sea further disturbed the water, adding to the chaotic surge, but it was the sheer scale of the caldera collapse that set off the largest and most destructive waves.

Crete was the first to be hit.

A 30-meter tsunami surged onto the northern coast, demolishing harbors and sweeping entire towns into the sea. The tsunami tore through the Mediterranean, reaching Turkey, Israel, and Egypt in mere hours, devastating coastal cities in its path. Ships in Alexandria, caught off guard, were hurled inland, smashing into buildings and sinking in flooded streets.

The fallout continued to spread. By the next day, ash had darkened the skies across the eastern Mediterranean, spreading eastward toward the Middle East. While the eruption’s immense force initially propelled ash in multiple directions, the prevailing trade winds prevented significant ashfall over much of Europe, instead directing the thick volcanic plume toward Turkey, the Levant, and beyond. Airports were shut down as jet engines choked on the debris. Crops in Greece and Turkey were buried beneath meters of volcanic ash. Acid rain began to fall as sulfur dioxide spread into the stratosphere, dimming the sun.

Entire regions were plunged into darkness. The Mediterranean became a disaster zone, with millions displaced by the combination of fire, water, and suffocating ash. Countries bordering the Aegean Sea were left in chaos, struggling to grasp the magnitude of what had occurred.

The Earth Chokes

Days passed, but the eruption did not stop. The Aegean was now a war zone of fire and water. The remnants of Santorini, a smoldering shell of its former self, were unrecognizable. The once-idyllic white buildings were buried beneath thick layers of pumice and ash.

As the volcanic plume reached the stratosphere, global temperatures began to drop. The dense veil of ash and sulfur dioxide circled the globe, blocking out sunlight. What was once a Mediterranean summer became a long, cold darkness.

Farms in Europe and Asia suffered devastating crop failures. Livestock died en masse, poisoned by tainted water and suffocated by falling ash. The world, unprepared for such a drastic shift in climate, began to spiral into crisis. Governments collapsed, and food riots erupted in major cities.

VEI Rating and the Scale of the Eruption

The eruption of Santorini in this event would be classified as a Volcanic Explosivity Index (VEI) 7—a super-colossal eruption. This rating is based on the immense volume of material ejected, the height of the eruption column reaching the stratosphere, and the widespread global effects. A VEI 7 eruption releases more than 100 cubic kilometers (24 cubic miles) of tephra, causing catastrophic environmental, atmospheric, and societal consequences. The last known VEI 7 eruption was the 1815 Tambora eruption, which caused the Year Without a Summer due to its impact on global climate. Santorini’s eruption would rival or even exceed this devastation, plunging the world into turmoil and reshaping entire regions.

Aftermath: A World Transformed

Historians compared the event to the Minoan eruption of 1600 BCE, which had once doomed an ancient civilization—but this time, it was not just a single culture at risk. The entire world now felt the weight of nature’s fury.

Santorini had not just erupted. It had reshaped the world.

Here's the video that we made on the eruption simulation of Santorini.