Volcanic ash is a silent killer, more so than lava: What Alaska needs to know with Mount Spurr likely to erupt
Volcanoes inspire awe with spectacular eruptions and incandescent rivers of lava, but often their deadliest hazard is what quietly falls from the sky.
When a large volcano erupts, as appears close to doing about 80 miles from Anchorage, Alaska, it can release . Fine ash can infiltrate the lungs of people and animals who breathe it in, poison crops and disrupt aquatic life. Thick deposits of ash can collapse roofs, cripple utilities and disrupt transport networks.
Ash may lack the visual impact of flowing lava, but as , I'm aware that ash travels farther, lasts longer and leaves deep scars.
Volcanic ash: What it is, and why it matters
forms when - molten rock from deep beneath Earth's surface - erupts, exploding into shards of rock, mineral and glass carried in a near-supersonic stream of hot gas.
Towering clouds of ash into , where the ash is captured by high-altitude winds that can carry it hundreds or even thousands of miles.
As the volcanic ash settles back to Earth, it that typically decrease in thickness with distance from the eruption source. Near the vent, the ash may be several feet deep, but communities farther away may see only a dusting.
Breathing danger: Health risks from ash
Breathing volcanic ash can irritate the throat and lungs, trigger asthma attacks and such as COPD.
The finest particles pose the greatest risk because they can and cause death by asphyxiation in the worst cases. Mild, short-term symptoms often resolve with rest. However, the long-term consequences of ash exposure can include silicosis, a lung disease and a possible cause of cancer.
The danger increases in dry regions where into the air again by wind or human activity.
Risks to pets and livestock
Humans aren't the only ones at risk. Animals experience similar respiratory symptoms to humans.
Domestic , eye inflammation and paw irritation from exposure to ash.
Livestock face greater dangers. If , it can damage their teeth, block their intestines and poison them.
During the in Iceland, farmers were advised to shelter sheep and cattle because the above the recognized safety threshold of 400 parts per million. Animals that remained exposed became sick and some died.
Harm to crops, soil and water
Soil and crops can also be damaged. Volcanic ash alters the acidity of soil and introduces harmful elements such as and into the environment.
While the ash can add nutrients such as potassium and phosphorus that enhance fertility, the .
Ash can , block sunlight and clog the tiny stomata, or pores, in leaves that allow plants to exchange gases with the atmosphere. It can also introduce toxins that render food unmarketable. Vegetables, fruit trees and vines are particularly vulnerable, but even sturdy cereals and grasses can die if ash remains on leaves or poisons emerging shoots.
Following the 1991 , vast tracts of farmland in central Luzon in the Philippines were rendered unproductive for years due to acidic ash and buried topsoil. If multiple ashfalls occur in a growing season, crop failure becomes a near certainty. It was the that followed the in 1815.
Ash can also by and increasing the water's acidity. The toxins can leach into groundwater, contaminating wells. Fine ash particles can also settle in waterways and and animals. During the 2008 in Chile, ash contamination led to widespread fish deaths in the Río Blanco.
Ash can ground airplanes, gum up infrastructure
Ash clouds are extremely dangerous to aircraft. The glassy ash particles melt when sucked into jet turbines, clog fuel systems and can stall engines in midair.
In 1982, lost power in all four engines after flying through an ash cloud. A similar incident occurred in 1989 to over Alaska. In 2010, Iceland's eruption across Europe, disrupting travel for over 10 million passengers and costing the global economy billions of dollars.
Volcanic ash can also by clogging water supplies, short-circuiting electrical systems and collapsing roofs under its weight. It can disrupt transportation, communication, rescue and power networks, as the 1991 in the Philippines dramatically demonstrated.
What to do during ashfall
During an ashfall event, the to stay safe is to stay indoors as much as possible and avoid inhaling ash particles.
Anyone who must go outside should wear a properly fitted N95 or P2 mask. Cloth masks provide little protection against fine ash. Rainwater tanks, troughs and open wells should be covered and monitored for contamination. Livestock should be moved to clean pastures or given uncontaminated fodder.
To reduce structural damage, ash should be cleared from roofs and gutters promptly, especially before rainfall.
, and people who are sick are at greatest risk, particularly those living in poorly ventilated homes. Rural communities that are dependent on agriculture and livestock are disproportionately affected by ashfall, as are low-income people who lack access to clean water, protective masks or safe shelter.
Communities can stay through official alerts, including those from the , which monitor ash dispersion and issue timely warnings. The also offers guidelines on personal protection, emergency planning and ash cleanup.
The long tail of ash
Volcanic ash may fall quietly, but its effects are widespread, persistent and potentially deadly. It poses a chronic threat to health, agriculture, infrastructure and aquatic systems.
Recognizing the risk is a crucial first step to protecting lives. Effective planning and public awareness can further help reduce the damage.
