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

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.

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.

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.

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.

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.

Although an estimated 99.999% of the deep ocean has not been explored, techniques such as sonar have been used to identify the deepest known point in each of Earth's five oceans.

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.

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.

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.

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.

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.

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.

Located in the Pacific Ocean, the Challenger Deep is the deepest point on Earth, extending to depths a mile deeper than Mount Everest is tall.

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.

Explore the deepest parts of the ocean

The deeps of the Earth's oceans are some of the most extreme environments on the planet. Take a trip 36,000 feet to the deepest parts of the sea in this informative, 10-minute animated video.

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

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

The transform boundary divides the opposing movements of the Pacific and North American tectonic plates, which create shear zones that distort and fracture rock. These movements produce shallow earthquakes as rocks are gradually displaced hundreds of miles.

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.

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.

Earth's oceans, which have an average depth of 3.7 kilometers (2.3 miles), may be divided into zones based on depth or the abundance of light.

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).

How deep is the Mariana Trench?

This five-minute video takes viewers to the depths of the Mariana Trench, emphasizing just how far below the bottom of the trench lies beneath our feet through comparisons to better-known objects and monuments, including the Eiffel Tower. The Statue...

NASA explores Earth's deepest oceans to prepare for space

By studying extreme environments in Earth's hadal zone—the deepest part of the ocean —NASA tests technologies, probes life under crushing pressure, and gathers clues about potential oceans and possible life on worlds like Europa and Enceladus.

Underwater volcanoes significantly contributes to marine extinctions during the Triassic period

An analysis of ocean basins in the Tibetan Plateau helped identify three major periods of volcanism—250-248, 233-231, and 210-208 million years ago—which released significant amounts of greenhouse gases, altering ocean chemistry. The low-oxygen conditions may help explain half of Earth's Triassic extinctions.

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.

Sinkholes form when underground cavities cause the surface above to collapse

These openings are typically carved by acidic water, which often forms in limestone-rich areas. However, leaking pipes, groundwater removal and extreme weather or geological activity increases the frequency of sinkhole appearances.

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

As of 2025, humans have only dug 0.2% the way to Earth's center

The Kola Superdeep Borehole revealed two billion-year-old fossils and underground water, but the immense temperature and pressure prevented further tunneling. Beyond those depths, scientists know of Earth's interior by analyzing how seismic waves move.

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.

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.'

An interactive of the deep sea

How diamonds form in the deep earth

Deep within Earth's mantle, diamonds form from carbon-bearing fluids. The formation of these beautiful gemstones, the only direct samples we have of the mantle, helps scientists uncover how carbon functions deep inside our planet. Understanding this complex process aids in the exploration for new diamond deposits.

The cycling of carbon via tectonic activity may have facilitated life on Earth

Plates sinking into Earth’s mantle pull carbon from the surface, helping stabilize the atmosphere and climate by removing greenhouse gases from volcanic eruptions. At the same time, magma is a significant contributor of heavy metals and other crucial minerals for life to the surface.

How we know what's deep inside the Earth, despite never traveling there

We'll likely never see the Earth's core, but we can make educated guesses about what it's like down there. Nearly as hot as the sun's surface and under impossibly high pressure, the inner Earths extreme conditions make it impossible to explore. Yet, seismic waves during earthquakes, volcanic eruptions, and light waves from the sun provide fascinating insights about our planet's mantle, crust, and core.

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.'

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.

Because seismic waves travel 100 times faster than tsunami waves—waves typically travel faster through solids than liquids—measurements of geological activity help tsunami detection systems provide early warnings.

Scientists define sea level as the elevation to which water would settle on Earth's surface, given the planet's gravitational field and rotation.

Take an interactive dive and see the animals that populate the oceans, from coral near the surface to shrimp-like organisms near the seafloor.

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.

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...

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.

Watch the destructive force of bottom trawling on marine ecosystems

Bottom trawling is a fishing method where a net is dragged along the seafloor to catch a species of interest. The process produces as much carbon dioxide yearly as global aviation and leaves trails of destruction large enough to be seen in space.

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.

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.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

Thunderquakes—seismic waves created when lightning strikes the ground—have enabled scientists to image underground environments near Earth's surface by detecting vibrations along subterranean fiber-optic cables.

Simulate geological activity at plate boundaries using virtual planetary models.

Remnants of another planet that helped form the moon may be beneath Earth's surface

Large mantle structures beneath Africa and the Pacific Ocean may be the buried remains of Thea, a large Mars-sized planet that collided with Earth. The theory is supported by isotopic evidence from volcanic and lunar rocks.