Warning: The following information is presented for educational purposes only.
Always seek expert local advice when traveling to a volcano.
Risk Zones Around an Active Volcano
1) Extreme Risk Zone. (0? to 100 m) This is the area within tens of metres of an active vent. This is the death zone. Only to be approached under extreme circumstances with a good reason to be there. Realistically there is never a good reason to be there. Only enter with a suitably qualified guide but don't even expect your guide to want to go here. This location is subject to intra crater earthquakes, extreme temperatures, choking and toxic gases, falling projectiles, and unstable terrain. An eruption may give 30 seconds warning at most. This region is incompatible with life. You will be killed if you stay there long enough. Limit your time in this area to minutes if you approach at all. It is suggested that you stay away from this zone. It is possible to stray into this zone without realising. An example is the collapse pit (Mbogon Niri Mbwelesu) on Ambrym volcano in Vanuatu. It can eject rocks 3 km out of the vent and people can walk past it without realising the danger. Examples of Extreme Risk Zone. Summits of Etna, Stromboli, Yasur, Anak Krakatau, Semeru, Sakura-jima, Santa Maria, Arenal, Pacaya, Galeras, Rabaul, plus others... If you don't know the current state of volcanic activity, then don't approach the vents!
2) High Risk Zone. (100 m to 300 m). This is the area on the edge of the crater. In an eruption you are in danger. You will only have a 50:50 chance of survival here in a larger than normal eruption. Limit time in this region. This is usually the closest you should approach an active volcano under ideal conditions. Don't even think of getting this close to volcanoes like Sakura-jima (Japan), Anak Krakatau (Indonesia), Rabaul (Papua New Guinea).
3) Medium Risk Zone. (300 m to 3 km). At any time bombs can be expelled to this distance. Think twice before sleeping here. Spending hours in this zone may be OK but keep a careful watch on activity and follow the instructions of guides. For example on Mt Etna in 2000 this zone suddenly became dangerous without warning when SE crater activated on over 60 occasions. Tourist operations never approach closer than this distance from volcano. Any closer requires experience and knowledge of volcanic conditions. For example on Stromboli volcano the medium risk zone is below 750m elevation, and low risk below 400 m elevation.
4) Low Risk Zone. (3 km to 10 km). There is a low risk of injury from an eruption in this zone. Bombs may fall in this zone during a large eruption. In July 2000 Copahue Volcano (Chile) expelled bombs to 9 km. Lahars or large pyroclastic flows may travel this far down valleys, otherwise it is usually safe. Eruptions of Volcanic Explosive Index 3 and over occur every few months somewhere on earth and create hazards in this area. Lava flows on basaltic volcanoes such as Mt Etna, Kilauea, and Piton de la Fournaise can travel this far.
5) Safe Zone for Habitation. (Beyond 10 km). Only a large eruption will affect this area. Rift zone effusive eruptions may send lava flows more than 10 km from the source. Areas on the flanks of Kilauea and Mauna Loa volcanoes in Hawaii beyond 10 km from the summit are at risk during an eruption. Lahars are capable of traveling over 10 km down the side of volcanoes. The great lahars of Nevado del Ruiz volcano (Colombia 1985) traveled 100 km and destroyed the town of Armero 73 km from the source. This accident was correctly forecast and the tragedy was a human made disaster. When Mt St Helens erupted in 1980, the blast effected region was over 25 km from the volcano. The eruption of Merapi volcano, Indonesia in 2010 sent pyroclastic flows 15 km from the crater. Such large eruptions occur about every 10 years somewhere in the world. Chances of being killed by a volcano are 1 in 80,000 over a lifetime. i.e. you would have to live 5 million years on average before you would be killed in this zone. Living 10 km from a volcano is no more dangerous than facing risks such as wild fires, hurricanes, floods, and earthquakes for other people around the world. Volcanoes are probably the least dangerous of all the major natural disasters. Making a judgment to enter these zones is a personal choice. People react differently under stress. Beware of the mesmerizing effect of a volcano. Like watching the waves crash on to the shore you can be lulled into a hypnotic state of false security. Donít stay too long. Volcanic activity can change without warning. Accidents at Galeras volcano, Colombia (1993), Masaya volcano, and Nicaragua (April 23rd, 2001) show that there are not always warning signs or the signs are ignored. Anatahan Volcano erupted on 10th May 2003 producing the first recorded eruption from this volcano. Scientists were on the volcano only the day before and noticed nothing unusual. Even volcanoes which have not erupted in 500 years can suddenly reactivate. Note:Dormant and extinct volcanoes can cause fatalities such as Altar (Ecuador, 2000), Santo Tomas Volcano (Guatemala, 1990), Toliman (Guatemala, 2002), and Hakkoda (Japan 1997).
Between 1980 to 2000 there were 34,000 people killed on volcanoes (23 were Volcanologists).
Safety Recommendations When Visiting an Active Volcano
1) Read about past eruptions.
Volcanic eruptions can repeat themselves. What the volcano has done in the past is what it is capable of doing in the future. While volcanoes are inherently unpredictable, studies of past eruptions at a particular volcano will give an indication of what is possible.
2) Read about past accidents.
Analyse what went wrong in past accidents. The Bulletin of the Global Volcanism Network (Smithsonian Institute) has the best monthly volcanic activity reports including accident reports. Two accidents have happened on field trips associated with International Volcanology conferences (Galeras in 1993 and Semeru 2000). Many scientists are inexperienced when it comes to climbing volcanoes. Theoretical knowledge is no replacement for field experience.
3) Observe the volcano for before getting close to the danger zone.
Note the frequency and types or eruptions occurring at the volcano. Sometimes a two to three day observation period is required before approaching the summit area. Simply arriving at the volcano and climbing straight to the summit is asking for trouble!
4) Know the current volcano warning level.
How does this compare to the "normal" state of volcanic activity. Volcano warning levels may be expressed in different forms. Warning levels may mean different things on different volcanoes. Learn what the current activity level means for the particular volcano you are visiting. Remember, most volcanoes are not monitored by scientists so don't rely on the authorities knowing the danger level. Absence of evidence is not evidence of absence. If there is no current eruption warning, it does not necessarily mean the volcano is safe!
5) Be self sufficient.
Do not expect other people to come into the danger zone and rescue you. Heroic rescue efforts like Galeras in 1993 cannot be relied upon. Don't expect people to risk their life to get you out of danger. It is "cargo cult" mentality to think that rescue will come from the sky in the form of helicopter retrieval, such as the Ambrym 2004 rescue of a film crew. .
6) Take the correct equipment.
Helmet, maps, compass, GPS, food, water, suitable clothing, gloves. If camping out then make sure you have suitable shelter. Volcanoes can be very wet places. An expedition level tent is required. During the accident at Galeras volcano in 1993, incredibly only one scientist of the group who entered the active crater wore a helmet! That scientist survived, and more lives would have been spared if others had done the same. A major cause of death was head impacts caused by falling rocks. There is mobile phone reception on some volcanoes so it may be possible to ring out in an emergency. However do not rely on this method alone because it is very unreliable. Two way radios may help but reception can be affected by topography.
7) Travel with a guide/volcanologist experienced in the local conditions.
Make sure the guide is experienced on the volcano. Local knowledge should always be sought when visiting a volcano. On the spot activity reports are more accurate than remote sensing data. For example eruptions on Mt Etna in 2000 were predicted at the crater edge 1 hour before seismometers picked up an increase in activity. Gas and ash emissions may not always be picked up remotely. Local guides may have good advice on recent volcanic activity.
An example of what can go wrong on a volcano trip was demonstrated in 2004 when a film crew went to Ambrym volcano in Vanuatu. The crew attempted to film the volcano, and failed to take a volcanologist. The crew had to be rescued from the volcano after one week, leaving behind thousands of dollars worth of equipment, a failed expedition, wasted filming budget, and lucky to escape with their lives. The small additional price of a volcanologist on the trip would have prevented this debacle.
If you are inexperienced and travel without a qualified guide into the danger area, you will put rescuers at risk when they try to retrieve your body (such as happened on Stromboli volcano in 1986).
8) Leave travel details with a responsible person.
Details should state your destination and when you will return. It should also contain a copy of the emergency plan and how to activate it. Some volcanoes are so remote that a disaster plan can only be very basic. It is always best to be self-sufficient and not rely on other people to rescue you.
9) Take all precautions in PREVENTING an accident.
Be very conservative in your actions. Don't assume the volcano is safe if everything looks quiet. It may be the "calm before the storm". A blocked vent can be quiet but the pressure can be building to a large eruption.
10) Obey local authorities.
Don't enter any area on the volcano if the local authorities prohibit it. Don't try to escape paying the proper climbing fees, and charges imposed by the authorities. Payment and registration with the local authorities is there for your safety.
11) Safety cannot be guaranteed at a volcano.
Safety on an active volcano cannot be guaranteed. Volcanoes can produce large eruptions without warning. Visiting an active volcano is like lying down of a freeway. If you stay there long enough you will be killed.
Precautions in the Danger Zone
1) Wear the correct equipment at all times.
Wear a helmet and take a gas mask. If your helmet is not strapped on at all times it is useless. Even effusive volcanoes like Kilauea may send dangerous projectiles into the air from lava sea-water interactions and methane explosions. Unstable ground can result in falls and head injuries.
2) Beware of many sources of danger on a volcano.
Extreme heat, cold, windstorms, heavy rain/ acid rainfall, lightning, altitude sickness, blizzards, getting lost, volcanic activity, unstable terrain, dangerous plants, animals, and insects. Volcanoes generate their own weather which can be severe and different from that only a few km away. Localised wind storms may reach 150 km/hr without warning. Cooling lava flows may still be deadly, when rain falling on the hot surface may displace breathable air after it flashes to steam (people died from the effect at Nyiragongo eruption in 2002). Beware that some areas may be high risk areas for robbery, kidnap, personal injury, civil unrest etc. Traveling to new regions may put the traveler at risk of diseases such as malaria, typhoid, food poisoning etc. Take all necessary prophylactic medication and immunizations. Getting to the volcano may be as dangerous than the volcano itself!
3) Survey the ground on approach to the crater.
Look for evidence of recent ejecta. If you can see recent bombs on the ground then you can be hit. Limit your time in that area. It is preferable you relocate to a safer zone. Some vents eject projectiles in a particular direction. Don't stay in the firing line. Recent bombs are black and stand out from the brown colour of older lava.
4) Watch out for rock falls and avalanches when climbing the crater.
Falling rocks and unstable ground pose one of the most immediate hazards when climbing a volcano. Don't kick rocks down the slope and try to limit your impact on the unstable terrain. Watch out for other climbers above and below you. The crater edge may be overhanging. Know where you are walking at all times. Be careful of new ground slumping or cracking. This will pose a risk because the edge of the crater may fall into the volcano. Cooled lava flows may look stable to walk on, but the crust may be thin, which would expose the hiker to a falling into a lava tube. There may even be flowing lava under a thin crust of pahoehoe lava. Falling into an active lava tube will be instant death.
5) Beware of Hazardous Gases.
Hazardous gases emitted by volcanoes include carbon dioxide, sulfur dioxide, hydrogen sulfide, radon, hydrogen chloride, hydrofluoric acid, and sulfuric acid. Gases can be toxic directly or displace oxygen from the environment leading to anoxia. Never enter a depression near active fumaroles, especially on a day without wind. Toxic gases can pool in the depression leading to a dangerous situation.
6) Can you directly see the vent?
If you can directly see the vent then the projectiles have a direct line of sight to you. Rocks and lava can be ejected at 200 m per second, sometimes even supersonic. You might be hit before you even hear the explosion. Lateral projectiles are some of the most dangerous and can be lethal in even a minor eruption.
7) Beware of periods of low activity.
Quiet periods at a volcano may lure you into a false sense of security, and make you go closer than you would otherwise. Beware of a quiet volcano!
8) Limit your time in the danger zone.
The closer you go to the vent, the greater the risks. In zone 1 (see above) even a minor eruption can be fatal. The risks multiply exponentially in this zone. Spend only minutes in this zone, if you need to be there at all. There is really no reason to be in zone 1 of a volcano. The scientists at Galeras made the fatal error of staying 4 hours in this area! Remember you will be killed here if you stay long enough. It is like sleeping on a freeway. Eventually something will hit you if you stay long enough. Some scientists enter the danger zone immediately after a large eruption because they believe the magma column may be lowered for a while. It takes a brave person to follow this line of thinking. [The author does not discount this theory, but also does not recommend it.]
9) Exit the danger zone well before sunset.
Start the climb early and exit by midday. If something goes wrong then rescue will be almost impossible at night. If you survive the accident then you may die of exposure during the cold night at altitude. Volcano watchers are early risers. Some climbs are started at midnight in order to arrive at the summit by sunrise for the best views. By 9 am the summit can be covered in cloud and visibility reduced.
10) Observe from a safe location.
Stay up wind and away from the direction of travel of projectiles. Have an evacuation plan with 2 exits. Mentally rehearse your escape plan continuously while in the danger zone. Vent migration may make a previously safe area off limits. Take time to study the volcano topography before going too close.
11) If caught in an eruption near the crater take cover.
You have a 50% chance of survival if you are caught in an eruption. Hiding behind boulders or in a depression will shield you from lateral projectiles. Watch for vertical projectiles. Fall times from 1 km can be around 14 seconds so there is time to see the larger ones coming, but weather you can take evasive action is debatable. From experience is is very difficult, or even impossible, to calculate projectile trajectories, and fall times. Evacuate the area as soon as possible. Re-assess your knowledge of the volcano and its eruptive history. Wearing gloves will prevent severe burns to the hands while escaping over glowing lava rocks. Inhaling hot ash is a major cause of death in pyroclastic flows. The lethal period may only last a minute. Motor vehicles offer little safety. An air tight building increases survival. (Note: A pyroclastic flow through a town is one of volcanology's most feared scenarios. It happened at Mt Pelee and Vesuvius).
12) Visibility may suddenly reduce to almost zero without warning.
This can be due to fog, vog, cloud, rain, volcanic fumes or nightfall. Be sure you can deal with these situations. Most people would have severe problems walking out of an area under these conditions. A familiar location will become a nightmare under limited visibility. If you find yourself in very low visibility then you may just have to sit and wait until conditions improve. Don't walk off a cliff and fall into the volcano. A GPS may be a useful navigation aid, but it will not allow safety close to active vents at night. Some volcanic zones involve climbing along knife-edge ridges. A GPS will not allow sufficient accuracy to navigate along these areas in limited visibility. Some volcanic areas have few landmarks to use in navigating.
13) Leave the area if it becomes dangerous.
There is no point having a safety plan if it is ignored. Two scientists were killed on Guagua Pichincha Volcano in 1993 when they remained in the crater despite getting a radio warning of possible eruption 85 minutes earlier.
14) Do not approach lava flowing through vegetation.
Underground explosions occur in front of lava flowing over burning vegetation. Plants burn without oxygen as they are covered by lava, creating methane gas. The gas fills underground lava tubes. When the methane ignites, the ground explodes up to 100 meters in front of the advancing lava flow. Rocks and debris blast in all directions.
See more on methane explosions.
15) Look for warning signs of an eruption.
Explosive activity may be preceded by earthquakes or rock falls. You may only have 30 seconds warning but this may give you time to take cover or evasive action.
16) Watch out for Heavy Rain.
Heavy rain can cause flash flooding and lahars.
Weighing the Risks of Volcanology Compared to Other Pursuits.
People usually underestimate the risks of the familiar and over estimate the risk of the unfamiliar. Here are some examples.
Underestimation of Risk
Motor vehicle accident, Accident in the home, Saturated fat in the diet.
Overestimation of Risk
Injury on a volcano, Shark attack, Plane crash, Preservatives in the diet.
A decision to climb an erupting volcano should be based on a risk-benefit analysis. To see an eruption is one of the greatest sights in nature but the challenge must be accepted with common sense and knowledge of the risks.
Contact John Seach for a volcano hazard assessment.