What Are Ground Fires and How to Survive Them: Complete Guide

Ground fires are subsurface wildfires that burn underground in organic materials like peat, humus, and decomposed vegetation beneath the forest floor. Unlike the dramatic flames you see in regular wildfires, ground fires smolder slowly without visible flames, burning for days, weeks, or even months at low temperatures. They spread unpredictably underground and can reignite surface fires long after you think the danger has passed.

To survive a ground fire, immediately evacuate the area if possible. If trapped, move to cleared ground free of vegetation, lie flat in a depression with your face down, cover yourself with dirt or non-flammable material, and protect your airways from smoke inhalation. The hidden nature of these fires makes them exceptionally dangerous—hot spots can collapse beneath your feet, and toxic smoke can linger at ground level where you’d typically seek cleaner air.

Understanding Ground Fires: The Invisible Threat

Walk through a forest after a fire has supposedly been contained, and you might notice something odd. The surface looks charred but quiet. Yet several feet below, an inferno continues to rage. This is a ground fire, and it represents one of nature’s most deceptive threats.

Ground fires burn in the accumulated organic material beneath the surface—the peat bogs, thick layers of decomposed leaves, humus, and buried roots that have built up over centuries. This material acts like concentrated fuel waiting for ignition. Once lit, these fires behave completely differently from the wildfires we typically imagine.

How Ground Fires Differ from Surface and Crown Fires

The wildfire family includes three distinct members, each with unique behaviors. Surface fires burn the loose debris on top of the ground—dried leaves, twigs, grass, and low shrubs. Crown fires race through tree canopies with towering flames and explosive energy. Ground fires operate in stealth mode underneath both.

Ground fires burn through sustained glowing combustion without flames and can go undetected for extended periods because they produce minimal smoke and spread slowly. While surface fires might race across grasslands at 14 miles per hour, ground fires creep along at barely a walking pace, sometimes taking months to travel just a few hundred yards.

The fuel makes all the difference. Surface fires consume litter such as dried leaves, twigs, and duff, while ground fires burn buried organic matter including peat and humus. This buried material is incredibly dense with carbon—think of it as nature’s coal reserves. When it burns, it releases enormous amounts of stored energy and greenhouse gases.

The Science Behind Underground Burning

Ground fires operate on a principle called smoldering combustion. Unlike the rapid, oxygen-hungry flames of surface fires, smoldering is slow, low-temperature, and flameless. The fire creeps through porous organic material, consuming it from the inside out.

Ground fires typically burn by smoldering and can burn slowly for days to months, such as peat fires in Kalimantan and Eastern Sumatra, Indonesia. The critical factor? Moisture content. When peat or humus dries out—whether from drought, drainage, or climate patterns—it becomes exceptionally flammable despite being underground.

The burning process creates voids and holes as the organic material is consumed. A typical depth of burn reported in several field studies is around 0.5 meters, which means the average fuel consumption per unit area is around 75 kg/m². These underground cavities pose immediate physical dangers. The ground above can look solid but collapse without warning, plunging you into burning peat below.

Why Ground Fires Are Exceptionally Dangerous

If ground fires move slowly and produce little flame, what makes them so hazardous? Several factors combine to create a perfect storm of danger.

The Hidden Killer: Detection Challenges

You can see a crown fire from miles away. Flames shoot hundreds of feet into the air, creating unmistakable warning signs. Ground fires offer no such courtesy.

Dry peat ignites very easily and can burn for days or weeks, smoldering underground and re-emerging away from the initial source, making these fires incredibly difficult to extinguish and highly unpredictable and uncontrollable. The fire might start from a small campfire or discarded cigarette, burrow underground, and travel dozens of yards before surfacing somewhere completely unexpected.

The smoke signature is minimal or absent, especially in early stages. By the time visible smoke appears, the underground fire may have already consumed a massive area. Even thermal imaging struggles with detection because the heat is insulated by layers of soil and organic matter.

Ash Pits: Nature’s Hidden Traps

Walking through an area affected by ground fires creates life-threatening hazards invisible to the naked eye.

Ash pits are holes in the ground created by burned tree roots, filled with hot ashes. These cavities remain dangerously hot for weeks after the visible fire has passed. Step on one, and the ground gives way, dropping you into superheated ash and embers. The results are catastrophic burns, often to the legs and feet.

Tree roots can burn underground while the tree above remains standing. The tree becomes unstable and can topple without warning. Root fires can reignite a wildfire or cause other natural hazards, and are dangerous to humans and animals if trodden over because the extreme heat can cause the soil to collapse.

The Zombie Fire Phenomenon

Perhaps the most unsettling characteristic of ground fires is their ability to survive conditions that would extinguish any normal fire.

Peat fires refuse to die even when flooded with water, making them “zombie fires” that can survive winter and reignite months later. Firefighters might drench an area with thousands of gallons of water, declare victory, and move on. Weeks or months later—sometimes after snow has fallen and melted—the fire resurfaces, having smoldered underground the entire time.

In peat or coal seams, ground fires may burn for decades and are notoriously difficult to put out as they can move underground. Some coal seam fires have burned for over a century. The town of Centralia, Pennsylvania, was abandoned because of an underground coal fire that has burned since 1962 and shows no signs of stopping.

Environmental and Health Impacts

The scale of destruction from ground fires is staggering. The 1997 Indonesia peat fire released emissions equivalent to 13-40% of global man-made emissions for that entire year. To put that in perspective, a single fire event matched up to 40% of what all of humanity’s factories, vehicles, and power plants produced in twelve months.

Peat fires can release 100 times the carbon that a wildfire does, making them significant contributors to climate change. The smoke from these fires is also particularly toxic. Peatland fires release mercury into the atmosphere at a rate 15 times greater than other types of wildland fires.

The health consequences reach far beyond the immediate fire zone. Smoke from major peat fires has traveled thousands of miles, creating public health emergencies across entire regions. In Indonesia, the 1997 fires caused respiratory problems affecting millions of people across Southeast Asia, including neighboring countries.

Warning Signs: Recognizing Ground Fire Danger

Early detection saves lives. While ground fires are inherently difficult to spot, certain signs can alert you to danger.

Environmental Indicators

Before a ground fire becomes obvious, the environment sends signals. Watch for areas where the ground feels unusually warm underfoot, even without visible flames. This warmth indicates underground burning.

Look for dying vegetation in patches that seem unrelated to drought or disease. When roots burn underground, the plants above begin to wilt and die even if there’s no surface fire. These dead or dying plant clusters often mark the underground fire’s path.

Notice depressions or sinkholes forming in previously flat ground. These indicate that organic material has burned away beneath, leaving cavities that eventually collapse. Areas near these depressions are at high risk of having more unstable ground.

Smoke and Smell Signals

Ground fires produce smoke that behaves differently from surface fires. The smoke often appears to seep from the ground itself, rising in wisps from cracks or disturbed earth. It has a distinctive, acrid smell—earthier and more pungent than wood smoke.

This smoke can linger close to the ground, forming a low-lying haze that’s easy to miss if you’re focused on looking for flames at eye level or higher. The smoke may appear intermittently, visible one moment and gone the next as underground air currents shift.

After a Wildfire: Extended Vigilance

The time immediately following a wildfire requires extreme caution. Just because the flames are gone doesn’t mean the danger has passed.

After a fire, maintain a “fire watch” for several hours, checking repeatedly for smoke, sparks, or hidden embers in the house, roof, and attic, while watching for hot spots that can ignite trees without warning. This vigilance should extend to the ground. Walk carefully, testing suspicious areas before putting your full weight down.

Hot spots can ignite trees without warning, so wear leather gloves and thick-soled boots for protection. These protective measures aren’t just recommended—they’re essential. The heat from underground fires can melt synthetic boot soles and cause severe burns even without direct flame contact.

Survival Strategies: What to Do If You Encounter a Ground Fire

Understanding ground fires is valuable, but knowing how to survive one is critical. Your response depends on whether you have time to evacuate or find yourself trapped.

Immediate Evacuation: Your First Priority

If you detect signs of a ground fire and have any opportunity to leave the area, do so immediately. Don’t wait to investigate or confirm your suspicions. The unpredictable nature of these fires means conditions can deteriorate rapidly.

Evacuate away from the fire and away from the direction it is moving, aiming for wide roads if feasible because narrow roads can easily become blocked. If you’re in a vehicle, keep doors unlocked and headlights on, even during the day. This helps rescuers locate you if conditions suddenly worsen.

Many people die in vehicles during wildfires, often because they waited too long to leave or thought their vehicle could outrun the fire. Remember that fires can “leapfrog” obstacles, appearing suddenly in areas that seemed safe moments before.

If Evacuation Is Impossible

Sometimes you don’t have time to evacuate. The fire might move faster than expected, or escape routes might already be blocked. In these desperate situations, specific survival techniques can mean the difference between life and death.

Find the Right Location

If you’re on foot in a wildfire, find a space with no vegetation and flammable material, and get as low as possible like in a ditch. Ground fires need organic fuel, so finding bare mineral soil, rock, or already-burned areas gives you the best chance.

Look for:

• Rocky outcrops with no vegetation
• Bodies of water (rivers, ponds, lakes)
• Previously burned areas where all fuel has been consumed
• Low-lying areas like ditches or depressions
• Roads or other cleared areas

Protect Yourself from Heat and Smoke

Lie with your face down and cover your body with water, dirt, mud, or nonflammable fabrics, using wool blankets rather than synthetic blankets because wool is more flame-resistant. Your positioning matters tremendously. Lying flat reduces your exposure to heat and smoke. Covering yourself with dirt or wet material provides insulation from radiant heat.

The greatest danger often comes from smoke inhalation, not direct flames. Use a cloth to act as a filter around your mouth, and remain calm. Panic increases your breathing rate, which means you inhale more toxic smoke. Slow, controlled breathing through a wet cloth or garment filters out some particulates and cools the air before it enters your lungs.

The Last Resort: Fighting Fire with Fire

In extreme circumstances where you’re surrounded with no escape, an unconventional technique might save your life. Creating a backfire by intentionally burning the area around you can create a safe zone, though this requires the right conditions and is extremely risky. This technique has historical precedent, used by both indigenous peoples and settlers on the Great Plains.

The concept is simple but dangerous: start a controlled fire in the vegetation around you and let it burn outward. When the main fire arrives, it finds only burned ground around your position and no fuel to sustain it. However, this only works if:

• You have time to let your fire burn enough area
• Wind conditions won’t push your fire back on you
• You can lie low enough to survive your own fire passing over
• The approaching fire is a surface or ground fire, not a crown fire

The key issue is to not inhale when passing through the flame—you will lose exposed hair and have burns on exposed skin. This technique should only be attempted as an absolute last resort when all other options have failed.

If You’re in a Structure

Close all windows, doors, and vents to prevent drafts from encouraging fire spread, but keep doors unlocked so you can escape and emergency workers can enter. Fill bathtubs, sinks, and any large containers with water. Soak towels and place them against door cracks to block smoke.

Shelter in interior rooms, noting that outer rooms will be hottest if the fire gets close. Stay away from windows. The radiant heat from a nearby fire can be intense enough to ignite curtains or cause glass to crack even if flames never touch the building.

Health Hazards: Understanding Smoke Inhalation Risks

Ground fires pose unique health risks, primarily through smoke inhalation. Understanding these dangers helps you protect yourself even when you’re not in the immediate fire zone.

The Hidden Threat in the Air

Smoke inhalation can damage airways and lungs, with chemicals in the smoke keeping your body from getting enough oxygen. Even if you’re miles from a fire, smoke can travel hundreds or thousands of miles and still affect your health.

Tiny particles can get everywhere through the bloodstream and trigger inflammatory pathways, exacerbating underlying cardiac and respiratory conditions. These particles are 30 times smaller than the diameter of a human hair, allowing them to penetrate deep into your lungs and enter your bloodstream.

Short-Term Health Effects

Immediate symptoms of smoke exposure include:

• Stinging eyes and runny nose
• Coughing, wheezing, and shortness of breath
• Scratchy or sore throat
• Headaches and dizziness
• Chest pain and rapid heartbeat
• Nausea and fatigue

Studies show consistent evidence documenting associations between wildfire smoke exposure and respiratory health effects, specifically exacerbations of asthma and chronic obstructive pulmonary disease. If you have pre-existing respiratory conditions, symptoms can worsen dramatically even with minimal smoke exposure.

Long-Term Consequences

The effects don’t always end when the smoke clears. Studies following children 2-4 years after exposure to smoke from large wildfires show reduced lung function, increased antibiotic use, and increased healthcare utilization. Repeated exposures compound these effects.

Wildfire smoke is about 10 times as toxic as regular air pollution from the burning of fossil fuels, and there’s no safe level of exposure. The more smoke you breathe, the worse the health outcomes become.

Who’s Most Vulnerable?

Certain groups face elevated risks from wildfire smoke:

• Children and teenagers (still-developing respiratory systems)
• Adults over 60 years old
• Pregnant individuals
• People with heart or lung disease
• People with asthma or COPD
• Outdoor workers

Risk is generally higher during childhood, lower in young adulthood, and greater in middle age through old age as the incidence of heart and lung disease, hypertension, and diabetes increases.

Prevention and Preparedness: Taking Action Before Disaster Strikes

The best way to survive a ground fire is to prevent its occurrence or be prepared before it starts.

Creating Defensible Space

If you live in or near wildfire-prone areas, creating defensible space around your property is essential. Keep all flammable materials away from exterior walls of the house, ensuring ground immediately surrounding your home is free of tall grass, mulch, dry leaves, pine needles, and firewood.

Plant trees and shrubs a minimum of 5 feet from the house, and if planting multiple trees within 30 feet of your house, space them at least 18 feet apart to prevent sparks from jumping from one to the next. Keep the ground around tree bases clear of vegetation to prevent surface fires from climbing trunks.

Regular maintenance matters. Clean your roof and gutters of dead leaves and debris. Install mesh screens in eaves and attic vents to catch embers. These small actions can prevent a ground fire’s embers from igniting your property.

Fire-Safe Practices in Natural Areas

Human activities cause the vast majority of wildfires, including ground fires. Unattended campfires are one of the common causes of wildfires. When camping or hiking:

• Check current fire danger ratings before starting any fire
• Use established fire rings when available
• Never leave fires unattended
• Ensure fires are completely extinguished before leaving
• Dispose of cigarettes properly—never toss them on the ground
• Avoid driving vehicles through tall, dry grass

Allow the fire to burn completely to ash, pour lots of water and drown all embers, stir ashes with a shovel and pour more water until all hissing sounds stop, and make sure everything is cold to the touch. This level of thoroughness prevents surface fires from becoming ground fires by ensuring embers can’t smolder into deeper organic layers.

Emergency Preparedness

Preparation before disaster strikes dramatically improves survival odds. Create a go-bag for each family member containing:

• N95 or P100 respirator masks
• Bottled water (one gallon per person per day for three days)
• Non-perishable food
• First aid supplies
• Flashlight and extra batteries
• Battery-powered or hand-crank radio
• Important documents in waterproof container
• Cash
• Emergency contact information
• Medications

If you have to evacuate, don’t make the potentially fatal mistake of trying to fill your car when danger is rapidly approaching—have your vehicle fueled in advance. During evacuation, traffic will be heavy and gas stations may be closed or overwhelmed.

Develop and practice an evacuation plan with your family. Know multiple exit routes from your area. Designate meeting points. Make arrangements for pets and livestock ahead of time.

Monitoring and Early Warning Systems

Technology provides tools for staying ahead of fire danger. Sign up for local emergency alert systems that send notifications about fire conditions. Download apps that track air quality and fire locations in real-time.

Check the Air Quality Index (AQI) regularly during fire season. When AQI reaches unhealthy levels, limit outdoor activities, especially strenuous exercise. Keep windows closed and run air conditioning on recirculate mode. Use HEPA filters indoors to clean the air.

The Growing Threat: Climate Change and Ground Fires

Ground fires aren’t just a current problem—they’re getting worse. Climate change is creating conditions that make these fires more likely and more severe.

Evapotranspiration is being enhanced and peatland water tables are lowering, leaving vast carbon reservoirs more vulnerable to fire, with fire seasons increasing in duration and starting a week earlier and ending a week later. Warmer temperatures, changing precipitation patterns, and longer dry periods all contribute to drying out the organic soils that fuel ground fires.

In recent years, fires frequently occur even in undrained bogs, and peat fires now spread further north, including beyond the Arctic Circle. This expansion means people in regions that never worried about ground fires now face this threat.

The consequences create a vicious cycle. Burning deep peat affects older soil carbon that has not been part of the active carbon cycle for centuries to millennia, creating a positive feedback to the climate system. As ground fires release ancient carbon, they accelerate climate change, which in turn creates conditions for more ground fires.

Living with the Threat: Long-Term Adaptation

Ground fires represent a challenge that won’t disappear. Learning to live with this threat requires both individual action and community adaptation.

Stay informed about fire conditions in your area year-round, not just during traditional fire season. The patterns are changing, and fires now occur outside historical timeframes.

Support and participate in community fire prevention efforts. Many areas have volunteer programs for clearing vegetation, monitoring fire conditions, and educating neighbors. These grassroots efforts make a measurable difference in community safety.

Advocate for better land management policies that reduce fire risk. This includes supporting controlled burns in appropriate areas, opposing drainage of peatlands, and backing regulations that limit development in high-risk zones.

If you live in a fire-prone area, consider investing in air filtration systems for your home. During extended smoke events, being able to maintain clean air indoors becomes essential for health.

Conclusion: Respect the Hidden Fire

Ground fires represent nature’s most patient destructor. They don’t race through forests with dramatic flames. They don’t create the pyrotechnics that draw news cameras. Instead, they smolder in silence beneath your feet, burning for months, resisting every attempt at suppression, and reigniting when you least expect it.

Their hidden nature makes them perhaps more dangerous than their flashier cousins. You can’t outrun what you can’t see coming. You can’t prepare for a threat that appears without warning.

But understanding these fires—knowing how they burn, recognizing their warning signs, and learning survival techniques—gives you the tools to stay safe. Combined with preparation, awareness of fire conditions, and respect for the power of these subterranean infernos, you can minimize your risk.

The ground beneath your feet holds incredible power. During fire season in vulnerable areas, that ground deserves your attention and respect. Stay alert, stay prepared, and remember that the most dangerous fires are often the ones you never see burning.