When the Earth moves : From Pangaea to the unpredictable Earth
(Pangaea broke apart. Continents drifted. And the Earth never stopped moving.)

Mangsatabam Dinachandra Meetei *

The World Before Our World

Imagine Earth about 200 million years ago. The Atlantic Ocean does not yet stretch between Africa and South America. India is far to the south of Asia. North America and Europe belong to a vast interconnected continental realm. Much of the world's land is gathered into a single supercontinent: Pangaea.

It is a world almost impossible to recognize today. Yet beneath this apparently solid landscape, Earth is already in motion.

Pangaea was never permanent. It was one moment in a much longer planetary cycle in which continents assemble, collide and separate. Earth's rigid outer shell is divided into immense tectonic plates, moving so slowly that their journeys are invisible to human eyes. Over millions of years, however, those tiny movements can redraw the planet.

Oceans open. Continents separate. Mountains rise. And sometimes the energy accumulated by these movements is released in seconds as an earthquake.

From Pangaea to Laurasia and Gondwana

Pangaea itself emerged from the collision and assembly of older continental masses. But by roughly 200 million years ago, it had begun to fragment.

Its northern realm became broadly known as Laurasia, containing the continental blocks that would eventually form much of North America, Europe and Asia. To the south lay Gondwana, an immense landmass incorporating South America, Afri- ca, Antarctica, Australia and India.

Between these evolving continental realms lay the ancient Tethys Ocean. But neither Laurasia nor Gondwana was permanent.

Gondwana gradually fractured. South America separated from Africa as the South Atlantic opened. Australia moved away from Antarctica. India broke free and began an extraordinary northward journey across an ancient ocean. Eventually, India collided with Eurasia.

The collision compressed and thickened Earth's crust, helping raise the Himalaya, a mountain system still being shaped by tectonic forces. The continents we know today were therefore not arranged once and for all. They were assembled and rearranged slowly by an Earth whose surface has been continuously changing.

The Plates Beneath Land and Sea

The phrase tectonic plate can sound abstract, but these plates are the moving pieces of This becomes especially important where different plates meet. When a dense oceanic plate encounters a less-dense continental plate, the oceanic plate can bend downward and sink beneath it in a process called subduction. As it descends into the mantle, enormous stresses can accumulate along the plate boundary.

In rarer circumstances, however, fragments of oceanic crust can be thrust onto a continental margin rather than disappearing into the mantle. This process, known as obduction, can preserve pieces of ancient seafloor on land as rocks called ophiolites. The Semail Ophiolite of Oman and the Troodos the planet itself.

Some portions of plates carry continents; others form vast stretches of ocean floor. Continental litho-sphere is generally thicker and less dense, while oceanic lithosphere is generally thinner and denser. Most large plates actually contain both continental and oceanic lithosphere, so plate boundaries rarely correspond neatly to coastlines.

Complex of Cyprus are among the best-known examples. Such remnants offer geologists a remarkable glimpse into oceans that vanished millions of years ago. Subduction zones, meanwhile, are among the planet's great geological danger zones. They produce some of the largest earthquakes ever recorded and can generate devastating tsunamis.

The Pacific Ring of Fire is a spectacular expression of this world of moving plates, where numerous tectonic boundaries encircle the ocean basin. The story of the continents, therefore, cannot be separated from the story of the oceans. The land beneath our feet and the ocean floor beneath the waves are parts of one restless planetary system.

A Planet Powered from Within

The engine of this restless world lies deep inside Earth. Our planet formed about 4.5 billion years ago from material orbiting the young Sun. Gravity drew that material together, while colli- sions and radioactive decay generated tremendous heat. Dense metals sank toward the centre to form the core, while lighter rocky material formed the mantle and crust.

Much of Earth's internal heat remains

The rigid outer shell, the lithosphere, is broken into tectonic plates. Beneath it lies the hotter, mechanically weaker asthenosphere. Dri-ven by processes within Earth and forces associated with interactions at plate boundaries, these plates slowly move. At some places they pull apart. At others they collide. Elsewhere they slide past one another.

These almost imperceptible movements have assembled and rearranged continents, opened oceans and raised mountain ranges. They also store the potential for sudden violence.

When Slow Motion Becomes Violent

A tectonic plate may move only a few centimetres in a year, but rocks along a fault can become locked by friction. The plates continue moving. The rocks deform. Stress accumulates. Energy is stored within the crust. Then, sometimes after decades, centuries or much longer, the resistance holding the fault together is overcome. The fault slips. Stored energy travels through Earth as seismic waves.

The ground shakes. An earthquake has begun. An earthquake is therefore not a separate story from continental drift. It is one of the sudden expressions of the same tectonic machinery that has been moving continents and building mountains for hundreds of millions of years.

Not every earthquake occurs at a plate boundary, and not every major earthquake generates a tsunami. But most large earthquakes are ultimately associated with the stresses produced by Earth's tectonic activity.

Continental drift is the slow face of a restless Earth. An earthquake is its sudden face.

When the Earth Shakes Beneath the Sea

When a powerful earthquake occurs beneath the ocean, the danger can extend far beyond the rupture itself. If the seafloor is suddenly displaced, it can push an enormous volume of water upward and generate a tsunami. Unlike ordinary wind-generated waves, a tsunami consists of a series of long waves capable of crossing entire ocean basins.

The 29 July 2025 Kam-chatka earthquake, with a magnitude of 8.8, provided a dramatic recent example. The offshore earthquake generated a tsunami that was observed throughout the Pacific Ocean basin, prompting warnings and advisories across distant coastlines. NOAA reported preliminary maximum tsunami run-up of about 17–19 metres in southeastern Kamchatka and the northern Kuril Islands.

The event demonstrated both nature's reach and modern science's growing ability to respond. Deep-ocean instruments and coastal tide gauges detected and tracked the tsunami, allowing scientists to refine forecasts as the waves travelled across the Pacific. Yet the earthquake itself had not been predicted before it began.

Recent Reminders from a Restless Planet

The 28 March 2025 Myanmar earthquake, magnitude 7.7, provided another stark reminder. The shallow earthquake occurred as a result of strike-slip faulting associated with the boundary between the India and Eurasia plates and was consistent with rupture of the Sagaing Fault.

USGS observations later showed a rupture extending roughly 475 kilometres, making it an extraordinary example of the scale to which a continental strike-slip earthquake can grow. Modern satellite and ground observations subsequently helped scientists reconstruct the movement of the fault in remarkable detail.

But understanding a rupture after it happens is different from knowing beforehand exactly when it will occur. This is the central paradox of earthquake science. We can increasingly observe the Earth in extraordinary detail. Yet we cannot reliably foresee its next great rupture.

Why Can't We Predict Earthquakes?

We can reconstruct Pangaea. We can trace the journeys of Laurasia and Gondwana. We can measure continents moving by centimetres each year. Satellites detect subtle deformation of Earth's surface. Seismometers detect earthquakes thousands of kilometres away. Scientists can map faults and calculate long-term seismic hazards.

Yet we still cannot reliably say: “A major earthquake will occur here at this exact time and with this exact magnitude.” The difficulty lies in the complexity hidden underground.

A fault is not a perfectly smooth crack. Its geometry, friction and rock properties vary along its length. Temperature, pressure and fluids can influence conditions at depth. Different faults can interact. Most importantly, scientists cannot directly observe every relevant physical condition kilometres beneath the surface. We can measure pieces of the system. We cannot yet see the entire system.

Prediction Is Not Early Warning

This distinction matters. Earthquake prediction would mean reliably specifying the time, location and magnitude of a future earthquake. Modern science cannot yet do this.

Forecasting is different. Scientists can estimate the probability of earthquakes occurring in particular regions over longer periods using geological evidence, fault history and statistical models. Then there is earthquake early warning.

An early-warning system detects an earthquake after rupture has already begun. Because some seismic waves travel faster than the strongest shaking, alerts can sometimes reach people farther away before destructive waves arrive. Those seconds can be precious. A train can slow down. Machinery can shut down. People can protect themselves.

For tsunamis, rapid detection and modelling can provide crucial time for coastal populations to evacuate. But early warning is not prediction. The earthquake has already started.

A Map Still Being Written

Pangaea is gone. Laurasia and Gondwana fragmented. The Atlantic opened. India crossed an ancient ocean and collided with Eurasia. The Himalaya rose. But the geological engine responsible for these transformations has never stopped.

Oceanic plates continue to form at spreading centres and descend at subduction zones. Continents continue their almost imperceptible journeys. Faults continue to accumulate stress. The ground beneath our feet appears permanent only because our lives are brief. To Earth, movement is normal.

A Planet That Still Keeps Secrets

The history of Pangaea, Laurasia and Gondwana reveals a planet whose surface has never been fixed. The earthquakes and tsunamis of our own time show that the forces responsible for that ancient rearrangement are still active.

A continental plate carrying a civilisation, an oceanic plate descending beneath it, a fault silently storing strain, an earthquake rupturing the seafloor and a tsunami travelling across an ocean may appear to be separate events. They are not. They are chapters of the same planetary drama.

We have become extraordinarily good at reading Earth's geological past and increasingly sophisticated at monitoring its present. We can measure continental movement, detect earthquakes within seconds and model tsunami waves across entire oceans.

But somewhere beneath the surface, rocks are deforming, plates are moving and stresses are accumulating. We do not know exactly when the next great rupture will occur. And perhaps that is the most humbling lesson.

The Earth that assembled Pangaea is the same Earth that broke it apart, separated Laurasia and Gondwana, raised the Himalaya, opened oceans and continues to shake beneath our feet.

For 4.5 billion years, the planet has been moving. We have only recently learned how to listen.