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.

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.

Avalanches happen when layered snow fails, often on perfect ski slopes

Snowpacks form unstable layers as weather shifts; a weak, refrozen layer buried under fresh snow can shear and release a slab avalanche on certain steep slopes. Triggers range from new snowfall to the movement of skiers, while survival depends on the presence of ski partners, beacons, and rescue teams.

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.

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.

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

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.

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.

Quicksand—a mixture of sand with clay or silt soaked in water that gives way when enough pressure is applied—is denser than the human body, meaning you naturally float inside it.

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.

Avalanches, which kill an average of 27 people in the US each year, typically require mountain slopes between 30 and 45 degrees and a layer of sturdy snow atop a weak, unstable layer, which can be put into motion by a trigger.

Tsunamis can last for days as their successive waves hit a coastal area, with early warning systems indicating the likelihood of a tsunami's arrival on a scale from watch to advisory to warning.

A tsunami—Japanese for 'harbor wave'—can begin with a drop in sea level before rising, which has contributed to its mistaken categorization as a tidal wave, despite being unrelated to the moon's gravity.

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.

In the US, flash floods—rapid floods that occur within six hours of rain—kill more people than tornadoes, hurricanes, and lightning.

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...

Although the term 'glacial pace' is associated with the slow movement of glaciers, during glacier surging, these massive bodies of ice can move over 60 meters (200 feet) a day.

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.

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.

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.

Glacial ice loss can be determined by listening to escaping bubbles

Glaciers form from the accumulation of layers of snowfall over hundreds to thousands of years, trapping air bubbles that serve as time capsules of atmospheric conditions at the time. When glaciers melt, these bubbles produce a distinctive sound that can be detected by underwater microphones, allowing assessment of melting from a safe distance.

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

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.

Why do flash floods occur?

Flash flooding can be more dangerous than traditional floods, occurring within the span of hours and exhibiting rapid currents. Here's how atmospheric conditions and geography combine to make some locations ripe for the disaster.

When struck, objects vibrate at unique rates called resonant frequencies, which makes tapping wood sound different from tapping metal, but providing objects with sound at their resonant frequency can cause them to shatter.

Tree rings can reveal centuries of environmental change and natural events

The width and shape of tree rings reflect yearly growth conditions like rainfall or snowfall. Scars in the rings can record disruptions such as fires, avalanches, or earthquakes, explaining when and how those events occurred.

Likened to a car backfiring or a faraway cannon fire, skyquakes have been reported worldwide in Earth's atmosphere without any obvious cause.

Modern landfills use layered liners, leachate systems, and gas monitors to safely contain waste

Today, landfill engineering is far more complex than a hole in the ground, which was largely the system cities used less than a century ago. This video explains how it actually works.

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.

Cooling lava naturally creates hexagonal cracks to evenly relieve stress

When lava cools and turns into rock, it contracts and builds up tension, particularly when held in place by the surrounding landscape. Just as drying mud cracks, initial cracks in the rock are random, but quickly organize into a hexagonal pattern, which scientists consider the most space-efficient shape.

The moon is slowly contracting as its interior cools, creating moonquakes and lobate scarps—cliffs that are steep on one side and gently sloping on the other—as the moon's surface buckles.

Eruption forecasting relies on probabilistic methods resembling weather forecasting

While some volcanoes erupt with predictable signs, such as surface deformation from the build-up of underground magma pressure, others release magma at inconsistent rates. Extensive monitoring is needed to identify less clear patterns and indicators of future eruptions.

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

Micro-seismic activity has been produced from people cheering or dancing at sporting events, concerts, and other large gatherings, but scientists can easily distinguish these vibrations from natural earthquakes using seismometers.

Explore how global teams coordinated by the UN's International Search and Rescue Advisory Group find and rescue survivors of large-scale earthquakes, from preliminary surveys to recovering bodies.

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.

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.

View a collection of sound animations, which depict how a source of sound waves pushes against particles to carry energy away without matter being displaced.

Experts reconstruct Pompeii’s daily life—and whether disaster could strike again

This documentary utilizes archaeology, X-rays, and 3D reconstructions to reconstruct what the streets, homes, and rituals of Pompeii looked like before 79 CE. Scientists also use satellite imaging to track landslide risks that could damage the site today.

Hearing loss can affect balance and make falls more likely

For reasons that are not yet fully understood, hearing loss seems to increase the risk of falls. One explanation is that reduced environmental awareness due to hearing loss may put people at greater risk. Another theory is that the brain has to work harder to process sound with hearing loss and that cognitive load may also boost the chances of falls. One study found that for every 10 decibel increase in hearing loss, there was a 1.4 fold increased odds of falling in the preceding 12 months.

The trend of onstage mishaps

In the past few years, performers have seen a rise in onstage accidents. While artists are doing their jobs, they face risks of dangerous falls, flying objects, and audience aggression. This article aims to explain why this trend may be occurring and emphasizes the importance of concert-going etiquette and adequate security.

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.

Tornado myths include suggestions to hide beneath a bridge or to open windows

Winds can accelerate due to a tunneling effect as they pass under a structure, making seeking shelter from a tornado in a mobile home or recreational vehicle highly discouraged. Significant tornado damage results from debris being picked up and hurled by strong winds, making it unsafe to be near windows that may shatter.

There are no outdoor locations that are safe from lightning

If your hair stands up amid an approaching storm, seek shelter immediately, as a local buildup of charge imbalance precedes cloud-to-ground lightning. If you are stuck outside, move to a lower altitude, such as a valley or ravine, and avoid open fields, water, and isolated tall objects. Do not lie down or crouch.

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

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.

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.

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.

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.

Thunder occurs when fast-flowing electricity heats and pressurizes air, causing it to expand and produce a shockwave at each point along the bolt at multiple frequencies.

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.