What is the Cascadia subduction zone?

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.

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

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

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.

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.

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.

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.

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

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.

View the 10 largest earthquakes ever recorded as of 2025, led by a 1960 magnitude 9.5 earthquake in Chile, which left about 2 million people unhoused.

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

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.

View a map of the distribution of mineral resources on the seafloor

Polymetallic nodules are found in regions near the middle of the Pacific Ocean, along the eastern coast of South America, and along the western coast of Africa, while cobalt-rich crusts span significant portions of the Pacific tropics east of the Philippines. Polymetallic sulfide deposits occur at tectonic plate boundaries, including areas within national jurisdictions.

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...

Explore an interactive map of volcanoes, earthquakes, and tsunamis from 2150 BCE to the present.

The CCZ is believed to harbor trillions of dollars of valuable minerals and thousands of undiscovered species

Located between Hawaii and Mexico and spanning an area larger than the European Union, the Clarion-Clipperton Zone is the world's region with the most contracts awarded to groups seeking to extract valuable metals by collecting polymetallic nodules. Conservative estimates suggest that 21.1 billion tons of polymetallic nodules exist in this abyssal plain, but about 90% of the species in the area are unknown to scientists.

The frequency of earthquakes and the distribution of their magnitudes have not changed significantly over long-term records, but technological improvements have enabled scientists to detect more of them as they occur.

See top-down views of Washington state's geology with cutting-edge lidar

Lidar is a revolutionary tool that creates visual models of landscapes using rapid light pulse measurements. Geologists in Washington state have deployed the technology to study the state's fault lines, landslides, tsunami inundation zones, and much more.

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.

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.

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).

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.

Many believe a cataclysmic volcanic eruption is imminent at Yellowstone, though experts say it is unlikely

Mike Poland, a scientist at the Yellowstone Volcano Observatory, estimates the likelihood of the event at one in a million. He cautions, though, that the park poses other potential dangers, including steam explosions and earthquakes.

NASA's GUARDIAN software uses changes in satellite navigation signals and AI-powered detection algorithms to anticipate tsunamis and provide real-time alerts to at-risk communities before the phenomena are detected by tidal sensors.

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.

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...

Visualize the power and frequency of earthquakes across the moment magnitude scale, where a whole number increase corresponds to about 32 times more energy released.

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.

The volcano threatening the Greek island of Santorini

Santorini is a popular tourist destination, known for its stunning white architecture and dreamy blue waters. Yet underneath the charming island is a potentially dangerous underwater volcano. Recent earthquakes have triggered nearly half of residents to evacuate, signaling heightened uncertainty about when the volcano could erupt. Researchers studying activity in the region plan to produce detailed hazard maps for Greek authorities to improve local safety and emergency planning.

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.

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.

The news feature that broke grunge

The Sub Pop label paid for journalist Everett True, then writing for Melody Maker, to fly to the sleepy northwestern city to check out the scene, which was breeding a curious mix of punk rock and heavy metal. The gambit worked. "The most vibrant, kicking music scene encompassed in one city for at least 10 years," Everett wrote.

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.

The best grunge albums of the 1990s

The best way to understand the music is to immerse yourself in it. This list compiles the definitive albums from the subgenre's peak period, featuring records from the big names associated with the scene (such as Nirvana, Pearl Jam, and Soundgarden) alongside less obvious picks that released grunge-adjacent classics (including Sonic Youth, Smashing Pumpkins, and PJ Harvey).

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.

Portugal's 1775 earthquake is considered Europe's first modern natural disaster.

British Columbia's 'Infinite Coast' is a hidden travel gem

The long expanse of Pacific coast north of the US border includes Victoria, Vancouver Island, the Great Bear Rainforest, fjords, whale watching, and 50 First Nations that manage the coastline. This site presents the region in an engaging interactive format to attract travelers looking for lesser-known areas of natural beauty.

Explore an interactive time-lapse of reported tsunami events since 1850, with identified cause, recorded observations, known deaths, and other information available for each.

Scientists determine earthquake locations by comparing how long it takes different seismic waves to be detected at three stations around the world, from which an origin, or hypocenter, can be triangulated.

Explore key locations in Kurt Cobain's life with this interactive map

The "Grungeology" project maps out key moments, influences, and impacts of Cobain's life in and around Grays Harbor County. Click through the map's many historical spots and learn how Nirvana's band leader navigated his hometown as his fame and music grew.

Listen to the 'Deep Six' compilation, one of the first collections of grunge

In the '80s, "grunge" was still not a widely used term, though there was a distinct sound coming from Seattle, one that blended punk and metal. C/Z Records decided to document the emerging sound in 1985 by releasing a compilation with six of the city's cutting-edge bands, including Green River, Melvins, and Soundgarden.

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.

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.

Travel through deep time with this interactive Earth

Explore key moments in Earth’s transformative history as continents drift and climate fluctuates over 4.6 billion years. The Smithsonian presents a series of interactive snapshots of the earth. From its toddler years during the Hadean period, when its surface was mostly molten, to the mostly unidentifiable landmasses of the future earth, 100 million years from now.

A nearby super volcano poses an even greater risk to Italy than Vesuvius

The Campi Flegrei supervolcano, with over half a million residents nearby, may be the region’s true threat. This BBC short shows how scientists monitor Campania’s volatile geology—and why people remain drawn to the landscape despite the danger.

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.

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

Mapping the Tongan eruption impact

A team of scientists—with the help of an uncrewed boat remotely controlled from the UK—join forces to produce one of the clearest pictures to date of what took place underneath the water as an enormous volcano erupted near the Tongan mainland.

As of 2025, the world's largest tropical cyclone spanned half the continental US

Typhoon Tip traveled across the western Pacific Ocean in 1979, achieving winds of 300 kilometers per hour. Though it weakened significantly before making landfall in Japan, its rainfall produced over 600 mudslides and killed 42 people.

View a gallery of diagrams for each volcano type with glossaries

The three major types of volcanoes—cinder cone, composite, and shield—each exhibit unique, lesser-known subterranean and surface features, including lava bombs, lahars, and spatter. Other types of volcanoes include lava domes, calderas, fissure volcanoes, and Maars and tuff rings.