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.

Lava flow viscosity plays a significant role in the type of volcano formed

Thin, runny flows spread quickly before cooling, producing expansive layers that build over time into wide shield volcanoes. The ejection and fast hardening of thicker lava flows and pyroclastic material create steep slopes and the characteristic cone shape of composite volcanoes.

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.

Volcanic ash is composed of fragments of volcanic rock, minerals, and glass

These abrasive particles are hazardous to aircraft. They can melt within engines and re-solidify on turbine blades, preventing forward propulsion. If inhaled, chemicals within ash can be toxic, and the particles can embed themselves into the lungs' ducts, causing suffocation.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Cerulean eruptions result from sulfur being heated by molten rock

During eruptions, warm-colored lava at temperatures between 700 and 1,200 degrees Celsius (1,300 and 2,200 degrees Fahrenheit) burns minerals as they escape from underground reservoirs. In some volcanoes, such as Indonesia's Kawah Ijen and Ethiopia's Danakil Depression, abundant sulfur compounds that burn with blue flames appear to change the color of the melted rock.

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.

Mount Vesuvius' ancient Roman eruption may have literally boiled blood

Mount Vesuvius erupted in 79 CE, sending ash and debris far and wide, burying several cities and the people inside them. This article details the various ways the blast killed those in Herculaneum. This seaside town was hit with the same ash and debris as Pompeii, and it was also hit by a wave of volcanic gases estimated to be more than 500° Fahrenheit, about 260° Celcius.

Human activities release 100 times the carbon dioxide of all volcanic eruptions

While gases released by volcanoes contribute to climate change, humans produce the carbon dioxide equivalent of a Mount St. Helens-sized eruption every 2.5 hours, or more than one Yellowstone eruption yearly, even though such supervolcanoes only erupt about every 100,000 to 200,000 years or more.

New evidence suggests the eruption's victims died as their blood boiled

While most Pompeii victims suffocated or were crushed, spectroscopic analysis of bones from a nearby town indicates something more extreme: exposure to superheated gas that instantly boiled blood and caused deadly internal trauma.

The list of historic volcanic eruptions includes the 1883 blast from Krakatau, which killed more than 36,000 and was the first such event to be documented in real time, thanks to the telegraph.

How powerful was the volcanic blast that destroyed parts of ancient Rome?

This article details how strong Mt. Vesuvius' powerful 79 CE blast may have been. Pompeii lay a bit further from the volcano's slopes than Herculaneum, a smaller seaside city. While Pompeii was mainly destroyed by ash and lapilli—glassy fragments of lava ejected during volcanic eruptions—Herculaneum was first hit by a scorching pyroclastic cloud of volcanic gas and other matter.

The composition of magma affects the explosivity of volcanic eruptions

Silicate-rich magma contains extensive molecular chains that trap dissolved gases like water and carbon dioxide. These gases build pressure until they violently escape, creating explosive eruptions. Low-silica magmas produce gentler eruptions categorized as effusive.

Extraterrestrial volcanoes spew material present during their formation

Unlike Earth's volcanoes that release lava, cryovolcanoes on distant moons erupt cold jets of water, ammonia, and other light gases present during the formation of their host planet. The movement of internal heat produced during formation is thought to drive icy plume movement.

View the 10 biggest volcanic eruptions in recorded history

The Mount Tambora eruption in 1815 was the deadliest and released so much sun-blocking ash and gas that 1816 became known as “the year without summer.” The resulting global food shortages are estimated to have killed over 71,000 people.

Supervolcanoes can eject enough material to fill one-fourth of the Grand Canyon

Although extremely rare, their released material can trigger winters by blocking the sun and cooling the Earth’s surface for years. The Toba supereruption 74,000 years ago disrupted food chains and reduced the human population to a few thousand.

Vesuvius has erupted nearly 40 times since Pompeii

With a 17,000-year history and dozens of eruptions since 79 CE, Vesuvius sits atop volatile geological forces that make it an unusually explosive volcano. This explainer breaks down why the volcano remains dangerous today.

The average eruption cycle of the Yellowstone supervolcano is 735,000 years

Eruptions a little over 2 million, 1.3 million, and 630,000 years ago indicate that the eruption is not imminent, though the sample size is small. Recent analysis reveals magma pockets are not interconnected, reducing eruption risk.

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.

Volcanic activity can lead to the formation of fertile soils

Ejected rock can introduce key minerals found in fertilizers, including iron, magnesium, and potassium, to improve soil quality. Ash and basalt crystals can be easily absorbed into soils, infusing them with sulfur, oxygen, chlorine, phosphorus, calcium, and other critical elements.

Volcanoes can be active, dormant, or extinct based on the recency of eruptions

Active volcanoes may be in the process of erupting or expected to erupt in the future, having done so within the past 11,650 years. Dormant volcanoes have no short-term eruption history, but are expected to erupt in the future, while extinct volcanoes lack the history and expectation.

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.

Could we throw trash inside volcanoes?

Americans toss out about 239 million tons of garbage each year. Some have wondered whether we could toss some (or all) of it into volcanoes, where it could be destroyed. There are about 1,500 active volcanoes on Earth, and many are pretty remote, making logistics complex. This video investigates whether the idea checks out.

A volcanic island north of Sicily is the world's longest continuously active volcano

Stromboli has been releasing lava for at least 2,000 years, with the earliest recorded eruption dating back to 350 BCE. Its mild but ongoing bursts of bright lava have earned it the nickname, "lighthouse of the Mediterranean."

The air around lightning can reach a temperature of about 30,000 degrees Celsius (54,000 degrees Fahrenheit)—five times hotter than the surface of the sun.

Volcanologist survives 5 eruptions while living on Mount Vesuvius

As physicist Luigi Palmieri ducked around lava flowing down the slopes of Mount Vesuvius, he also solidified the field of volcanology. This article details his contribution to science through his dangerous ventures to the volcano that buried Pompeii...

Volcanoes in the 1340s likely helped trigger the Black Death

The "bubonic plague" that wiped out roughly half of Europe and Asia originated from many factors. Recent research suggests volcanic eruptions contributed as well. The "aerosol" effects of matter released from eruptions likely prompted famine and accelerated the spread of infected fleas riding on grains avoiding spoilage.

How did people survive the eruption in Pompeii?

In 79 CE, Mount Vesuvius erupted and buried Pompeii under roughly 20 feet of volcanic ash. This deadly eruption killed much of the city’s population, but archaeologists recently discovered evidence of survivors. In this podcast episode, classicist Steven Tuck challenges the popular belief of total annihilation and explains how people may have survived, and how they continued to live after the disaster.

Rising wildfire smoke can create 'fire clouds'—towering clouds that can help combat fires through downbursts of rain or complicate firefighting efforts by triggering new fires via lightning strikes.

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.

With a height three times that of Mount Everest and an area roughly the size of Poland, the Martian shield volcano Olympus Mons is the largest volcano in the solar system.

If the Earth stopped spinning, 85% of the world's population would experience supersonic winds

The planet's equator moves about 470 meters per second—over 1,000 miles per hour—and air there would continue moving at this speed for several minutes if the ground stopped rotating. These conditions would cause tsunamis, global storms, and fling debris fast enough to destroy nearly all human-made structures.

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.

Io, Jupiter’s moon, is the most volcanically active body in the solar system

The innermost and third-largest of Jupiter’s four Galilean moons, Io’s volcanic activity is driven by tidal heating from Jupiter’s gravitational pull. Its atmosphere is very thin and primarily composed of sulfur dioxide, and its volcanic eruptions can exceed 1,000°C.

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.

Electricity can be lethal because it can disrupt the nervous system, which controls critical bodily functions that rely on electrical signals between cells, such as breathing and heart rate.

What happens if you throw trash into lava?

Each year, the world generates more than 2 billion tons of waste. Some have wondered: Could we dispose of it in lava? This video explores the science behind that idea, from lava lake temperatures to steam explosions and toxic emissions, and why the risks outweigh the benefits.

Located on Ross Island in Antarctica, Mount Erebus is the southernmost active volcano on Earth and features a lava lake—one of eight known worldwide as of 2026—that erupts regularly.

Humans were forced to adapt to survive a supervolcano eruption 74,000 years ago

The Toba supereruption ejected 2800 cubic kilometers of ash, resulting in global cooling from blocked sunlight and acid rain. Archaeological sites show that humans developed bow-and-arrow technology to survive in arid conditions by fishing in seasonal waterholes.

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.

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.

In 2009, accidentally drilling into magma provided time capsules of volcanic glass

While drilling for geothermal energy in Iceland's Krafla Geothermal Field, magma encountered at a depth of 2,100 meters quickly formed glass upon making contact with drilling fluid. By trapping dissolved gases, volatile chemicals, and the physical characteristics of magma before cooling, the glass acts as a time capsule of ancient volcanic activity and magmatic conditions.

When Mount Vesuvius erupted in 79 CE, it buried the Roman city of Pompeii under 20 feet of ash, which preserved it for nearly 1,700 years.

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.

Scientists monitor volcanoes with a suitcase-sized observatory called SKATE

Short for Setup for the Kinematic Acquisition of Explosive Eruptions, the device is left to record heat, sound and visual data while volcanologists remain at a safe distance. The $58,000 tool is the successor to the FAMoUS (Fast Multiparametric Setup) prototype.

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.

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.

Large igneous provinces are regions of massive ancient volcanic activity

Linked to some mass extinction events on Earth, LIPs contain significant amounts of igneous rock formed by the release of lava and gases over millions of years. India's Deccan Traps and the Siberian Traps are prominent examples of LIPs, whose climate-related impacts can serve as models for analyzing modern climate change.

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.

A look at hydrothermal vents, where barophiles and hyperthermophiles survive boiling water

Discovered in 1977 during an exploration of the Galapagos Rift, these seafloor openings spew hot magma and chemicals that heat seawater to hundreds of degrees. Without the sunlight found at depths of less than 1,000 meters (3,281 feet), extremophiles in these environments convert released chemicals into energy to survive, alongside surviving extreme pressures.

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.