The San Andreas Fault is an example of tectonic plates sliding past each other

Tectonic earthquakes are caused by tectonic plates sliding past one another at fault zones, deforming rock through friction as energy builds like a stretched rubber band.

Some tectonic plates move faster than their underlying convection currents

Like a chain slipping off a ledge, as tectonic plates sink, their weight can pull the rest of the trailing plate forward, accelerating their movement. Plates can also break apart and fall, creating a suction effect that drives movement, resembling leaves following a passing car.

Deep-sea trenches form when one tectonic plate subducts another underwater

Oceanic plates sink when colliding with less dense continental plates, bending the seafloor into steep depressions that can be almost 11 kilometers deep. Many of Earth’s strongest earthquakes occur at these plate boundaries, often featuring volcanic activity.

View a map of the world's major earthquakes from 1956 to 2022, which can be used to identify tectonic plate boundaries.

Explore case studies of each type of convergent plate boundary

At these boundaries, a collision of two oceanic plates produces a curved chain of volcanic islands, like those seen in the Caribbean. A continental-continental plate collision results in plates buckling upward, forming large mountain ranges.

View maps of seafloor topography, earthquakes, and volcanic activity, which scientists use to create outlines of Earth's tectonic plates.

Earth’s major tectonic plates make up 95% of its surface

Tectonic plates are pieces of Earth’s lithosphere, which consists of the crust and the solid, upper layer of the mantle. Segments of major plates can break and form minor or microplates, whose total number varies based on ongoing geological activity.

Convection flows in Earth’s mantle drive the movement of tectonic plates

These processes transfer heat from Earth’s core to the surface via rising magma plumes, while cooler, denser rock falls into the mantle at rates similar to human fingernail growth. These rates are determined by combining seismic data with computer simulations to model Earth’s interior.

View examples of rift valleys, the product of surface divergent boundaries

At these boundaries, tectonic plates move apart, stretching and thinning Earth’s crust as long valleys are formed from smaller, interconnected valleys and troughs. Ongoing rifting and erosion can further sink the valley, becoming a rift lake if volcanic activity becomes inactive.

The Ring of Fire, which spans 40,000 kilometers (24,900 miles) around the Pacific Ocean, is the most geologically active region on Earth.

Scientists determined that tectonic plates moved the ocean floor by observing symmetric patterns of magnetic stripes on opposite sides of underwater volcano systems, which could only result from seafloor spreading.

When oceanic plates sink beneath tectonic ones, they can generate magma

At converging oceanic-continental plate boundaries, the subduction of the oceanic plate introduces seawater that reduces the melting temperature of the overlying mantle. This causes it to melt into less dense magma, which can rise to fuel more volcanic activity.

200 million years of tectonic plate movement

The Earth's internal forces have continuously pushed and reshaped how the planet's land masses are arranged. From one supercontinent hundreds of millions of years ago, to present day, the Earth has looked dramatically different throughout the...

Simulate geological activity at plate boundaries using virtual planetary models.

Predicting earthquakes is difficult because different rock types can withstand different amounts of stress before breaking and melt at different temperatures within Earth's interior, introducing uncertainty into predictive models.

Slab pull and ridge push contribute to convection-driven oceanic crust movement

Through ridge push, after magma is projected up from the mantle, it cools and sinks, allowing gravity to help push older oceanic crust away. As this crust sinks into the mantle at deep-sea trenches, it pulls on the trailing crust behind it, accelerating ocean crust movement.

Although earthquakes cause about 80% of tsunamis, almost all earthquakes lack sufficient energy to cause the sudden shift in the ocean floor needed to substantially displace enormous volumes of water.

If, not when: An earthquake is destined to destroy the Pacific Northwest.

When the Cascadia fault line ruptures, it could be North America’s worst natural disaster in recorded history. Read a deep dive into the history of the region and the potential impact of the eventual seismic boom.

What is the Cascadia subduction zone?

A look at the Cascadia subduction zone, where the historical record suggests the Pacific Northwest is due for a devastating mega-earthquake in the coming years.

Just as light bends at different angles as it travels through different materials, seismic waves move in different directions through Earth's interior, revealing the presence of layers with varying properties.

Ancient sunken plates may influence mantle convection and surface motion

Research suggests sunken tectonic plates can collide, assemble, and break apart to form structures called large low-velocity provinces. LLVPs can significantly enrich rising magma plumes with elements commonly seen on Earth’s surface.

Some earthquakes can produce smaller tremors called boomerang earthquakes, which travel in the opposite direction and ripple back to the original earthquake's source.

Watch 1 billion years of tectonic plate movement in 40 seconds

Researchers at the University of Sydney developed the model, incorporating changing plate boundaries rather than just moving continents, to better understand the changes to biological and climatic systems throughout Earth’s history.

The theory of plate tectonics was not initially accepted until evidence became undeniable

Alfred Wegener proposed continental drift—the movement of large landmasses—in 1912 to explain why similar rock layers, plant and animal fossils, and glacial deposits were found on continents that were then unconnected. In the early 1960s, this was combined with evidence of seafloor spreading, mantle convection in Earth's interior, and earthquake and volcanic data outlining plate boundaries to produce the accepted theory.

How the Turkish earthquake created a 100-mile rupture

A February 2023 earthquake devastated parts of Turkey and Syria destroying entire blocks, with more than 50,000 people killed. A scientific analysis revealed a fault line with a 100-mile-long rupture, where separate tectonic plates moved more than...

Mid-ocean ridges are underwater volcano systems where tectonic plates diverge

New ocean crust is formed at these ridges as magma rises from Earth’s mantle and fills the space between the spreading plates. The speed of divergence influences ridge shape, with slow spreads forming rugged valleys and fast spreading creating smooth, wide slopes.

View the past month of earthquakes worldwide with this digital globe, which displays data from the US Geological Survey.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Most volcanic activity occurs in submarine volcanoes on the seafloor

At divergent plate boundaries in mid-ocean ridges, volcanic activity produces new ocean crust as the seafloor spreads. These areas are home to underwater mountains with extensive biodiversity due to redirecting ocean currents and concentrating food for marine life.

The theory of plate tectonics first emerged from the theory of continental drift

German meteorologist Alfred Wegener proposed that the continents were all one giant landmass in the past, which he named Pangaea. Despite geological and climate evidence suggesting continental movement, his theory was dismissed until the 1960s.

Records of Earth's magnetic field on the seafloor validated plate tectonics

Matching glacial, fossil, and rock records, mountain ranges, and continental shapes across oceans was insufficient evidence for continental drift. Precise measurements of magnetic minerals on the ocean floor revealed seafloor spreading, which could only be explained by moving landmasses.

A strike-slip fault and glaciers created Scotland's unusually straight Great Glen

In satellite images, Scotland's highlands present an unusually straight line in the landscape to viewers. This line occurs along a fault where two plates move against each other horizontally. Amid recent ice ages, receding glaciers deepened this fault.

Hawaii formed from oceanic plate movement over a hot spot in the mantle

Abnormally hot magma rose through the crust and emerged from the seafloor, where it cooled and piled onto layers that became tall enough to form an island. As the plate moved, the existing island moved away and a new one formed over the hot spot, repeating for each Hawaiian island.

Rather than predicting them in advance, earthquake early warning systems detect tremors moments after they begin and send notifications that reach users before the seismic activity does.

Continental drift is supported by matching evidence across disconnected continents

Mesosaurus fossils are found in South America and Africa, but these freshwater creatures could not have travelled across the ocean between continents. Rock layers in the Appalachian Mountains match those seen in Europe, indicating that the mountain belts were once connected.

While landslides are associated with the downward flow of unstable terrain, the term encompasses a variety of geological processes, which are distinguished by how the material moves and what materials are involved.

Instead of the tectonic plates found on Earth that produce earthquakes, volcanoes, and other geological activity when they interact, Mercury, Mars, and the moon have continuous, unbroken shells of rock called 'stagnant lids.'

Explosive volcanic eruptions happen when magma pressure overcomes rock strength

Magma usually stays underground because of a balance between its upward pressure, the weight of the Earth’s crust above, and the crust’s rock strength. Landslides can reduce crust weight, while built-up gas pressure can strengthen magmastatic pressure.

After a landslide, repeat activity may follow the appearance of cracks, springs of water, or dirt, sand, and rocks tumbling down from scars—exposed portions of Earth where the initial landslide began.

Earthquakes of identical magnitudes are unlikely to cause equal damage because magnitude only measures energy released, and earthquake severity depends on environmental factors, such as local architecture and geological conditions.

American oceanographic cartographer Marie Tharp's discovery of the Mid-Atlantic Ridge, which supported the idea that continents move over time, was initially dismissed as 'girl talk.'

What makes the Earth shake?

Researchers are demystifying the science of earthquakes—from their origins deep within the Earth to the scales that measure their strength. This article, which was part of a series of weekly reports from Cornell University, serves as a guide to...

Some scientists hypothesize that stressed rocks can discharge built-up static electricity in the form of lightning—a phenomenon known as fracto-luminescence, or earthquake lights.

Wave tanks can be used to create and study the impacts of tsunamis by building tension in an underwater object before allowing it to slip and rapidly displace water.

Scientists investigate Earth's interior by studying seismic waves

Scientists investigate Earth's interior by studying seismic wavesBelow Earth's atmosphere lies the crust, which extends to the Mohorovičić discontinuity between five and 20 miles below Earth's surface. Below the crust lies the mantle, the liquid-metal outer core, and the solid inner core, which surpasses 5,200 degrees Celsius (9,392 degrees Fahrenheit).

The formation and breakup of Pangaea altered Earth’s geology and biodiversity

Coming from the Greek words for “all” (pan) and “Earth” (gaia), the supercontinent existed from about 320 million to 195 million years ago. The tectonic activity that split Pangaea into today’s continents may one day bring the continents back together, forming Pangaea Proxima.

The world's largest earthquake simulator is an 800-ton shake table facility in Miki, Japan, which was built to test the resilience of structures after the 1995 Kobe earthquake killed over 6,000 people.

Because the Richter scale was calibrated to crustal and mantle properties in Southern California, seismologists have instead used the moment magnitude scale to quantify earthquakes since the 1970s.

Earth's inner structure is a dynamic system of layers in constant, slow motion

From the crust to the core, each of Earth's layers—some solid, some liquid—plays a role in generating its magnetic field, moving tectonic plates, and cycling matter. These details are determined through modeling since humans have only drilled 12 kilometers underground.

Explore landforms that exist across America's national parks

Landforms are not just scenic vistas; they are geological storytellers that shape ecosystems, climates, and our understanding of Earth's history. In this comprehensive look at landforms from the National Park Service, you will learn not only about different types of American landforms, but you will understand how these geological features are shaped by various forces, how they reveal an area's geological history, and how they influence climate and ecology.