Active volcanoes in the US are volcanoes that have erupted in the recent geologic past or show signs they could erupt again. Knowing which ones sit near you lets you plan for ash, mudflows, and evacuation before any warning comes. Older counts put the number at 65 active volcanoes across the states and territories. The U.S. Geological Survey (USGS) now tracks about 161 potentially active volcanoes and rates 18 of them as a very high threat.
You may live near a Cascade peak, on the Big Island of Hawaii, or hundreds of miles downwind of either. A volcanic eruption is a spontaneous natural disaster, but most give some notice. Days or weeks of small earthquakes and ground swelling usually come first. That lead time is your advantage. A three day kit and a one week plan carry most families through the first stretch of an eruption.
Start by finding the volcano nearest your home on a USGS volcano map. Then sign up for the free USGS Volcano Notification Service. You will get an email the moment that volcano's alert level changes.
Know the Active Volcanoes in the US by Region
Knowing which region you live in tells you which volcanic hazards belong on your family's list. Each region has its own type of volcano and its own type of trouble. Monitoring and alert levels come next, because they set your timeline.
Five Volcanic Regions
Alaska and the Aleutians: Alaska holds more than 50 volcanoes that have erupted in recorded history. Most sit far from towns, so their main threat is ash drifting into the busy flight paths between North America and Asia.
The Cascades: This chain runs from northern California through Oregon and Washington. It includes Mount St. Helens, Mount Rainier, Mount Hood, Mount Baker, and Mount Shasta. These peaks sit close to large cities, which puts them high on the USGS threat list.
Hawaii: Kilauea and Mauna Loa on the Big Island erupt often. Their lava flows are usually slow, and their volcanic gas is a steady concern for people living downwind.
The Mariana Islands: These US territory islands in the western Pacific include Pagan and Anatahan. Small populations and long distances make evacuation the main tool there.
Yellowstone and the West: The Yellowstone caldera in Wyoming and Long Valley in California are large calderas under constant watch. They mostly produce earthquakes and ground movement, not eruptions.
Monitoring
The USGS runs volcano observatories for Alaska, the Cascades, California, Hawaii, and Yellowstone. Scientists track earthquakes, ground swelling, and gas output. Their job is to alert the public and airlines when a volcano starts to wake up. USGS seismologist Seth Moran has described this as constant monitoring, with warnings issued when an eruption looks likely.
Remote and urban volcanoes need different warnings. "For a remote volcano, airlines need to know that a volcano might erupt so they are prepared to change their route to avoid the ash," said John Eichelberger, who coordinated the USGS Volcano Hazards Program. For a volcano near towns, he said, people may need dust masks, may need to stay out of a danger zone, or in extreme cases may need to evacuate.
Alert Levels
The USGS uses four ground alert levels. Normal means background activity. Advisory means unrest above normal. Watch means an eruption is possible or underway with limited hazards. Warning means a hazardous eruption is likely or underway. Aviation uses matching color codes of Green, Yellow, Orange, and Red.
Treat Advisory as your cue to check your kit. Treat Watch as your cue to fuel the car and review your route. The island volcanoes come next, starting in the far western Pacific.
Island Volcanoes Erupt on Their Own Schedule
The island volcanoes show how preparedness works when the nearest help is far away. You get a picture of what eruptions look like in practice, from full evacuation to living beside an active lava lake. The mainland volcanoes follow after these three.
Pagan Volcano
Pagan Island is part of the Mariana Islands archipelago. The chain lies south of Japan and just west of the Mariana Trench, home of the deepest spot on Earth. Pagan is one of the largest and most active volcanoes in the archipelago, according to the Smithsonian Global Volcanism Program. A major eruption in 1981 forced the island's residents to evacuate. Satellites still catch Pagan sending up ash and gas plumes from Pagan Island from time to time.
Pagan shows that a small island community survives an eruption by leaving early and leaving together. If your family lives on a remote island, keep your go-bags packed and your documents in one waterproof pouch. A quick boat or plane evacuation then becomes a calm departure.
Anatahan Volcano
When Anatahan first erupted in 2003, the island's 23 residents were already gone. They had been evacuated during strong earthquake activity in 1990. Anatahan erupted again over the following years, with activity lasting into 2008. Its ash clouds were large enough that NASA satellites captured the Anatahan eruption spotted from space.
The lesson from Anatahan is about timing. Earthquake swarms came 13 years before the first eruption. A volcano can rumble for a long time, and steady planning beats a last-minute scramble.
Kilauea Volcano
Kilauea is one of the most active volcanoes in the world. It is a shield volcano, built from layer after layer of runny lava. It forms the southeastern side of the Big Island of Hawaii. Its summit rises about 4,000 feet above sea level, and it covers about 14 percent of the island's land. The summit caldera holds the crater Halema'uma'u, said in Hawaiian tradition to be the home of the volcano goddess Pele. Live Science has a good summary of Kilauea's history and geology.
In 2018, Kilauea's lava flows destroyed hundreds of homes in the Lower Puna district. The flows moved slowly, so people had time to get out, but the homes could not be moved. Kilauea also releases vog, a volcanic smog made of sulfur dioxide gas and fine particles. Vog irritates eyes and lungs, especially for children and anyone with asthma. The mainland volcanoes behave very differently, as the Cascades and Yellowstone show.
The film Volcano (1997) imagines lava pouring through the streets of Los Angeles, with crews racing to steer the flow away from buildings. Real flows like Kilauea's usually move slower, so your family's advantage is the time to leave with your papers and medications, not a plan to stop the lava.
Mainland Peaks Under Watch
The mainland volcanoes matter most to the largest number of families. You get the specific hazard for each one and what it means for the towns around it. The preparedness steps for each hazard come right after.
Mount St. Helens
Mount St. Helens in Washington State erupted on May 18, 1980. A side of the mountain collapsed, and the blast flattened forests for miles. Fifty-seven people died. Ash fell across eastern Washington and into several other states. Streetlights came on at midday in towns more than 80 miles away.
The mountain is still active. It built a new lava dome inside its crater between 2004 and 2008. Today it shows how far ash travels from a single eruption.
The film Dante's Peak (1997) tells a fictional version of this story, with a USGS scientist tracking earthquakes under a Cascade peak while ash and mudflows close in on the small town below it. The real lesson is the same one St. Helens taught: the warning signs come first, and families who act on them early get out with time to spare.
Mount Rainier
Mount Rainier is a snow and ice capped volcano near Seattle and Tacoma. Its biggest threat is the lahar, a fast mudflow of melted snow, rock, and ash that pours down river valleys. Lahars move like wet concrete and can bury a valley floor. Towns such as Orting sit on old lahar deposits. Pierce County runs lahar sirens, posts evacuation route signs, and holds school drills.
A lahar can come with little warning, so your plan is the fastest way uphill, not out of town. If you live in a mapped lahar zone, walk your route to high ground with your family. Time it. Most routes take only minutes on foot.
Yellowstone
Yellowstone sits in Yellowstone National Park in Wyoming, on top of a huge caldera. The caldera floor rose almost 3 inches per year between 2004 and 2008. Since 2009 the uplift has slowed, though the movement of the ground remains hard to predict. The region often records swarms of small earthquakes, sometimes more than a hundred in a single month. These swarms are a normal part of a living volcanic system.
Headlines about a supereruption get attention, but the USGS considers one very unlikely in any human lifetime. The more likely events are hydrothermal explosions, steam blasts from hot springs, and earthquakes. Live Science explains what a Yellowstone supervolcano eruption would involve, along with the odds.
If you live near Yellowstone, your earthquake kit does most of the work for you. Secure heavy furniture, store water, and keep a three day supply of food. That same kit covers a volcanic emergency too. Live Science also keeps a list of the most dangerous US volcanic regions if you want to compare your area with others.
Prepare for the Hazards of Active Volcanoes in the US
Matching your preparedness to the right hazard keeps your family safe and your money well spent. You get supplies and steps for ash, lahars, lava, and gas, sorted by where you live. Each step answers the problem the step before it creates.
Ash
Volcanic ash is not soft like fireplace ash. It is tiny bits of rock and glass. It scratches eyes, irritates lungs, clogs engines, and shorts out electronics. Wet ash is heavy enough to collapse a roof.
Masks: Stock N95 masks for every family member, so everyone can breathe more easily outdoors during ashfall.
Eye protection: Keep goggles with a snug seal, and switch from contact lenses to glasses during ashfall to avoid scratched eyes.
Sealing supplies: Lay in plastic sheeting and painter's tape to cover vents and electronics, which keeps ash out of your living space.
Spare filters: Put by extra air filters for your car and furnace, because ash clogs them within days.
Once ash settles, cleanup becomes the next job. Dampen ash lightly before you sweep it, so it does not rise back into the air. Shovel it off flat roofs before rain makes it heavier. Keep ash out of drains, where it hardens like cement.
Lahars
If you live in a river valley below a Cascade volcano, learn your county's lahar hazard map. Find the nearest high ground and practice reaching it on foot. Agree on a meeting spot, because phones may be jammed. A lahar zone sounds alarming, but it is also a well-mapped hazard. Your route is set in advance, and drills turn it into a habit.
Lava and Vog
If you live in Hawaii, lava flows usually give you hours or days to leave. Keep important papers, photos, and medications in one grab box so you can evacuate in minutes. For vog, stay indoors with windows closed on bad air days. A portable air purifier helps your family sleep better on those nights.
Distance
If you live hundreds of miles from the nearest active volcano, ash is still your likely hazard. Your distance is also your advantage, since you will get hours of notice before ash arrives. Use that time to cover open water sources, bring pets inside, and park cars in the garage.
Water and Food
Ash contaminates open water, such as rain barrels, ponds, and uncovered tanks. Store sealed drinking water at one gallon per person per day. Aim for a one week supply if you live near a volcano. Shelf-stable food that needs little cooking covers the same week. Many preppers already keep this food and water on hand, and it serves a volcanic eruption as well as a storm.
Evacuation
Fill your gas tank when the alert level reaches Watch. Ash makes driving slow and dangerous, so leave early rather than late. If you must drive in ash, go slowly with headlights on, since ash cuts visibility and makes roads slick.
