Volcanoes have shaped some of the world’s most productive landscapes, leaving behind fertile soils, natural harbours and landscapes that have supported communities for centuries. The same geological forces that enrich the land also create hazards that can return with little warning. Around the world, millions of people continue to live beneath active volcanoes, accepting the risks because their homes, livelihoods and local economies remain closely tied to these landscapes. WorldAtlas lists the cities that might face frequent ashfall, while others worry about lava, toxic gases or destructive mudflows that can travel many kilometres from the summit.Modern monitoring systems have improved early warning capabilities, but they cannot eliminate the danger. These cities illustrate the delicate balance between opportunity and risk, showing how communities have adapted their daily lives to some of the most active volcanic regions on Earth.
Cities built in the shadow of an active volcano
World’s most dangerous cities built in the shadow of active volcanoes
Orting, Washington
Orting lies south of Seattle in a broad valley created by rivers flowing from Mount Rainier. The scenery is peaceful, with farmland spreading across rich volcanic soil, but geologists know that the ground beneath the town tells an older story. Much of the community stands on deposits left behind by an enormous lahar that swept through the valley roughly five centuries ago.Unlike lava, lahars behave more like fast-moving wet concrete. They can carry rocks, trees and buildings over great distances while following river valleys. Mount Rainier has produced several of these flows during the past several thousand years, and studies suggest another could eventually reach Orting within an hour, leaving little time for evacuation.Because of that possibility, the town has developed one of the country’s most comprehensive volcanic emergency programmes. Sirens are tested regularly, schools practise evacuation drills alongside fire drills, and clearly marked escape routes lead residents towards higher ground. The volcanic soil continues to support farming, which remains one reason people have continued living here despite the long-recognised hazard.
Toutle, Washington
The 1980 eruption of Mount St. Helens changed the landscape around Toutle more dramatically than almost anywhere else in the region. Entire forests disappeared beneath volcanic debris, bridges were destroyed and river channels filled with ash and sediment carried downstream by powerful mudflows.The community still lives with the aftermath. Each year, rivers draining Mount St. Helens transport large amounts of volcanic material towards lower valleys. To reduce the threat, engineers constructed the Sediment Retention Structure, a specialised dam designed not for water storage but for trapping debris before it reaches populated areas.The structure has prevented enormous quantities of sediment from moving farther downstream, and further upgrades are planned to maintain its effectiveness. While Mount St. Helens remains closely monitored, the surrounding communities continue to rely on both engineering projects and scientific observation to reduce future risks.
Mammoth Lakes, California
Mammoth Lakes occupies the edge of one of North America’s largest active volcanic systems. Beneath the ski resorts, forests and hot springs sits the Long Valley Caldera, formed hundreds of thousands of years ago after a massive eruption emptied an enormous magma chamber.Although another eruption is not considered imminent, the volcanic system remains active. One of its most unusual hazards is invisible. Carbon dioxide escapes naturally through cracks in the ground, collecting in low-lying areas where it can displace oxygen. In several parts of Mammoth Mountain, this gas has killed extensive areas of forest, leaving stands of dead pine trees that remain visible decades later.Monitoring stations continuously measure gas emissions, ground movement and earthquake activity. Buildings in vulnerable locations are equipped with carbon dioxide detection systems, while scientists track small changes beneath the caldera that could indicate renewed volcanic unrest.
Pahoa, Hawaii
Life around Pahoa has been shaped repeatedly by Kīlauea, one of the world’s most active volcanoes. Rather than producing explosive eruptions, Kīlauea often releases lava through long fractures in the ground known as rift zones, allowing molten rock to emerge many kilometres from the summit.The eruption that began in 2018 transformed large sections of the surrounding district. Lava buried roads, destroyed hundreds of homes and permanently altered the coastline in several places. Some neighbourhoods disappeared beneath fresh volcanic rock while others narrowly escaped the advancing flows.Even after the eruption ended, volcanic activity continued elsewhere on Kīlauea. Residents remain familiar with hazard maps that divide the island into different lava-risk zones, and property buyers routinely consider those maps before choosing where to live. The landscape continues to evolve as new eruptions periodically reshape the island.
Kagoshima, Japan
Daily life in Kagoshima unfolds under the watch of Sakurajima, one of Japan’s most active volcanoes. Small eruptions occur so frequently that local people often treat drifting ash as part of ordinary life rather than an unusual event.Ashfall influences everything from transport to agriculture. Weather forecasts include predictions showing where volcanic ash is expected to travel, helping residents prepare for changing conditions. Municipal authorities distribute collection bags specifically designed for ash disposal, while regular street cleaning helps prevent accumulation.Schools have long adapted to the environment as well. During periods of increased volcanic activity, children may wear protective helmets outdoors because of the possibility of falling volcanic fragments. Despite these adjustments, Kagoshima continues to prosper through its busy harbour, tourism and agriculture, with volcanic soils supporting crops such as tea, rice and the well-known Sakurajima radish.
Naples, Italy
Few large cities live as close to active volcanic systems as Naples. Mount Vesuvius rises directly above the metropolitan area, while the vast Campi Flegrei caldera stretches beneath the city’s western districts. Together they place millions of residents within reach of future volcanic activity.Vesuvius last produced a significant eruption during the Second World War, though its most famous event remains the eruption of 79 CE that buried Pompeii and Herculaneum beneath ash and volcanic debris. Scientists consider another eruption inevitable at some point, even if there is no reliable way to predict exactly when it will occur.Emergency planning has therefore become part of everyday administration. Authorities maintain evacuation plans covering hundreds of thousands of residents inside designated danger zones, with transport by road, rail and sea forming part of the strategy if warning signs appear. The fertile volcanic landscape continues to support vineyards and tomato farms, while Naples itself remains one of the Mediterranean’s most important ports. For many people, the advantages of living here have outweighed the geological uncertainty for generations.