Volcanoes

Volcanoes come in many shapes and sizes, and their eruptions vary hugely in both frequency and intensity. Many volcanoes are tourist attractions and are worth a visit provided you take due care, in particular keeping a safe distance from eruptions.

Eruptions are extremely dangerous; the worst of them cause complete devastation over wide areas, sometimes with a large death toll. Despite the risk, due to the renowned fertility of volcanic soil, there are often large agricultural settlements close to volcanoes.

Understand
Neither volcanoes nor eruptions are particularly common. A list at the Smithsonian shows 1319 volcanoes which have erupted in the Holocene Epoch (since the end of the last Ice Age, about 10,000 BCE). Another shows frequency of eruptions 1960-2022; the range is 52 to 90 eruptions per year, most of them small. After an eruption most volcanoes will be calm for a while before pressure builds up enough for another blast; the interval can be anything from a few weeks to many centuries, depending on the local geology. There are hundreds of active volcanoes around the world, but many more that are dormant or extinct. One can still appreciate the awesome power of nature from these volcanoes, without the hazards that go with active ones.

Measurement scale
There is a scale for the force of eruptions called the Volcanic Explosivity Index or VEI; the main factor is the volume of ejecta, the amount of material spewed out. The scale is logarithmic; a VEI-5 eruption produces at least 1 km3 of ejecta, VEI-6 10 km3, VEI-7 100 km3, and VEI-8 1000 km3.

Really large eruptions are quite rare. The 20th century had three VEI-6 eruptions, ten VEI-5, and a few thousand smaller ones, but none of VEI-7 or above. As of early 2024, the 21st century has not had any VEI-7 or larger events either.

There have been only four or five VEI-7 events in the last 2,000 years – Lake Taupo (New Zealand) in 180 CE, Ilopango (El Salvador) around 431, Mount Paektu (on the Korean-Chinese border) around 946, possibly Mount Rinjani (Indonesia) in 1257, and Mount Tambora (Indonesia) in 1815. As for VEI-8, there has not been such an event in recorded history; the most recent was at Lake Taupo about 26,500 years ago.

The VEI-7 Tambora eruption of 1815 put out 160 cubic km (38 cubic miles) of ejecta, including enough dust and ash to cause "the year without a summer", widespread crop failure and some famine as far away as the US and Europe. Said "year without a summer" led the German Karl Drais to invent a "walking machine" which is today considered the first ancestor of the modern bicycle.

Classifying volcanoes
According to the Smithsonian Global Volcanism Program, the major volcano monitoring organization based in Washington, DC, volcanoes can be classified as follows: However, there is no international consensus on these definitions; each organisation may use somewhat different terms or different definitions. In any case, the terms are not precise; a volcano classed as active may do nothing interesting for hundreds of years, and volcanoes considered dormant sometimes erupt. A volcano classed as extinct is quite unlikely to come back to life, but there is no absolute guarantee. Perhaps the best-known type of volcano is the stratovolcano which is built up from multiple layers of ash and lava over centuries, giving a conical shape. Several of the world's most famous volcanoes, such as Mount Fuji, Krakatoa, Vesuvius and Mount Etna, are of this type. Filipino tourist literature claims their Mayon Volcano has the world's most perfect cone.
 * active if
 * it has erupted within the last 10,000 years (recently in geological terms)
 * or it shows considerable activity – hot springs, fumes, earthquakes, etc.
 * dormant (French for sleeping) if it is considered active but is currently quiet
 * extinct if it is no longer active

A complex stratovolcano has multiple cones or multiple calderas; examples include Kilimanjaro, the Three Sisters in Oregon and Taal Volcano in the Philippines.

A somewhat less common type is a shield volcano, formed when the lava is less viscous and therefore spreads out much further. Most of Hawaii's volcanoes are of this type. A phreatomagmatic eruption may have huge explosions when a large amount of water is instantly turned to steam on contact with superheated magma. The 1883 eruption of Krakatoa was VEI-6, much smaller than the VEI-7 Tambora eruption a few decades earlier, but it is more famous because the explosions were absolutely enormous. The Hunga Tonga eruption of 2022 was similar since that volcano is under the sea.

A strombolian eruption is not very powerful (VEI-1 or 2) but may last a long time. Stromboli has been erupting more-or-less continuously for several thousand years.

Supervolcanoes
Supervolcanoes are the largest volcanoes on Earth, but are not easily recognizable as such. Many are so big that, for many years, even geologists did not appreciate that these features were volcanoes in their own right. "Volcanoes form mountains; supervolcanoes erase them. Volcanoes kill plants and animals for miles around; supervolcanoes threaten whole species with extinction by changing the climate across the entire planet."

- National Geographic

Supervolcanoes are generally in the form of large calderas, which are giant volcanic depressions formed either by large explosive eruptions or quiet long-term drainage of magma. They often have associated lava flows or domes, and in many cases there are smaller volcanoes within the caldera. Many of the calderas are now lakes, and sometimes the smaller volcanoes are islands in the lake.

Examples of supervolcanoes include Yellowstone in the United States, Lake Toba and Mount Tambora in Indonesia, the Phelgraean Fields near Naples in Italy, Lake Atitlán in Guatemala, and Lake Taupo in New Zealand. Most supervolcanoes have undergone unimaginably huge eruptions (VEI-7 or 8) in the geologic past; these are what created the huge caldera. However, such eruptions are tens or hundreds of thousands of years apart. There is no reason to worry that Yellowstone, for example, will explode during your visit; it had several huge eruptions in the past, but none since a VEI-8 event 640,000 years ago.

Geothermal areas
Throughout volcanic areas of the world, one may also encounter geothermal areas. These places are often, but not always, associated with volcanic activity. Hot springs, geysers, mud pools and fumaroles (steam/gas vents) are common scenic features in geothermal areas, and hot springs can be great places to take a dip. Countries such as Japan, South Korea, Taiwan and Iceland are especially famous for hot spring baths. Geothermal areas are also an environmentally friendly source of energy, and Iceland takes advantage of this very well.

Yellowstone National Park is probably the best known example of a geothermal area, as molten magma lies not far beneath its ancient caldera. Nearby Thermopolis, Wyoming has the world's largest hot spring plus a dinosaur museum and Native American petroglyphs. Geysir in Iceland, which is the namesake for all geysers in the world, is another famous geothermal region. New Zealand, with its volcanoes in the North Island, is also known for extensive geothermal areas, with Rotorua perhaps being the best known one. The indigenous Maori people of New Zealand, who traditionally cooked their food by burying it underground with heated rocks (known as a hangi), often make use of the geothermal heat instead if they live in a geothermally active area. Similarly, Iceland has a tradition of baking rye bread underground using the geothermal heat. Kamchatka in Russia is known for its picturesque Valley of the Geysers, but its remote location makes it only accessible by helicopter, meaning that it receives far fewer tourists than the other places mentioned here.

Stay safe
Scientists can make predictions about volcanic activity, and those predictions are good enough to make it essential for travellers to check for current warnings when planning any trip to a volcanic area. However, the problem is complex and not all volcanoes are closely monitored, so predictions are generally not precise and sometimes not entirely reliable. Local media or tourist offices are the usual sources for warnings, but many countries have a government-run volcano monitoring organization which is the definitive source. Public safety authorities may order hazard areas evacuated and visitors should certainly follow such advice. However, the onset of some volcanic events can be quite sudden, and authorities are sometimes slow to act since evacuations are disruptive, expensive and sometimes controversial. When an order is given, it may be difficult to comply since transportation may be disrupted or overcrowded.

If you are near a volcano that begins to act restless &mdash; perhaps earth tremors or expelling steam or dust &mdash; you should consider leaving the area without waiting for an evacuation order. "Get out while the gettin's good."

Volcanoes are complex and can be quite different from each other, so for most of them it is a good idea to have an expert guide who knows the particular mountain you want to visit. On the other hand, climbing some volcanoes without a guide is reasonable; for example Mount Fuji has not erupted since 1708, scientists are not issuing warnings, and there are well-marked trails.

Volcanic activity is often associated with earthquakes or tsunamis, and some volcanoes are high enough that altitude sickness is a risk. Each of those has another whole set of hazards; see the linked articles.

Equipment
Good footwear is essential since many volcanic rocks have sharp edges and some are hot; also, the terrain is often irregular and good boots will reduce the risk of a stubbed toe or turned ankle. A sturdy pair of hiking boots are the usual choice; look for thick soles, preferably in a material such as Vibram which does not melt easily.

Other equipment &mdash; such as heavy work gloves, a helmet, safety googles, a walking stick, a facemask for dust or a gas mask for poisonous fumes &mdash; is sometimes needed as well. For some volcanoes, mountaineering skills and equipment are needed. On a few, snakebite is also a hazard and high leather boots are the simplest protection.

Hazards
Volcano hazard zones can extend for dozens of kilometers, and there are multiple hazards.

An erupting volcano is extremely dangerous. Unless you have an excellent reason for going near one, the best advice is to stay away and watch it from a considerable distance, or even from the safety of your home or hotel on the TV news. It takes a major eruption to destroy a city, create or sink an island, or produce a huge death toll, but even the smallest eruption can destroy buildings and kill people. Even in areas with highly developed tourist infrastructure, there can be dangers - in 2019 a hiker was killed by a violent, unexpected eruption on Stromboli and twenty-two died when Whakaari / White Island erupted while a number of tour parties were visiting it.

"It's tempting to go to the throat of the volcano to get the data, because if you do you're a hero ... It's a battle between your mind and your emotions. If your emotions win out, you can get yourself in a lot of trouble."

- Ken Wohlitz

Hazards found only during eruptions are:

Other hazards are present whether or not the volcano is erupting: Any of those can kill, but the ones that claim the most lives are pyroclastic flows and lahars because they often occur suddenly, they move very fast, and they can travel surprisingly long distances. Do not go anywhere that they are likely. If you get hit by either of these, your chances of survival are almost zero. If you are in the path, you are unlikely to outrun it, even with a vehicle; your best chance may be to try to get off the path by moving perpendicular to the flow or diagonally.
 * Lava is molten rock spewing forth from the volcano. In addition to the direct danger, a large lava flow radiates enough heat to ignite vegetation and kill animals at a considerable distance.
 * Pyroclastic flows are streams of red-hot ash and debris that rush downslope from their source vents, incinerating anything flammable in their path. They can reach temperatures up to 800°C (over 1400°F) and travel at up to 150 km/h (almost 100 mph).
 * Volcanic bombs are rocks thrown upward by eruptions; many are ejected as blobs of molten rock that solidify while airborne, so they may still be dangerously hot when they land. Large ones are generally not thrown far or high, but they can be any size up to that of a house and are spectacularly dangerous. Smaller ones can be thrown thousands of meters high and may land dozens of km away, and even an egg-sized rock can kill if it drops from a great height. A hard hat will reduce this danger somewhat, but not to anywhere near zero.
 * Jökulhlaups are floods caused by the volcano melting parts of a glacier, possibly a part that functions as dam of a glacier lake. On Iceland there have been peak discharges in the order of magnitude of floods of the Amazon River. Bridges downstream from Vatnajökull used to get destroyed on a regular basis. Volcanoes can also cause floods when a crater wall collapses releasing the lake within, by melting snow that is not part of a glacier, or by blocking rivers.
 * Lahars are avalanches of mud created when a deposit of volcanic ash becomes mobile when it gets wet from rainfall or from a flood. They can occur long after eruptions, travel many kilometers at high speed, and be devastating. While there are usually some warning signs before eruptions, lahars often occur with no warning.
 * Steam is dangerous, perhaps just scalding but in some cases (Krakatoa or some geysers) explosive. In many cases, hot water or hot mud are nearly as hazardous.
 * Lethal gasses are gasses from eruptions or from vents, typically carbon dioxide and sulphur dioxide; assume any vent with steam may also have nastier gasses. Often, but not always, the stink of sulphurous compounds provides a warning; avoid areas with a rotten egg smell. Also try to stay upwind of any vents releasing gasses. Walking toward a vent, keep the wind at your back; walking away, keep it in your face.
 * Vog or volcanic smog is a nasty combination of water droplets with dissolved gasses, possibly plus volcanic dust. Since SO2 in water becomes sulphurous acid, this is highly irritating to eyes and throat. In high concentrations or for vulnerable people — asthma, heart or lung disease, children, pregnant women, the elderly, etc. — it can be fatal. If you are exposed, a face mask gives some protection and drinking lots of water will soothe the throat.
 * Falling rocks and landslides are more probable when the earth is restless. Avoid steep slopes and cliff edges, and be cautious if you need to be in vulnerable places.

Staying on high ground when observing a volcano gives you a better view and reduces several hazards. The dangerous gasses are heavier than air and collect in low-lying areas, and lava, pyroclastic flows, lahars and floods all tend to follow the contours of the land. A combination of distance and altitude also reduces the risk from volcanic bombs. Often the best place to observe is from high on the other side of a valley, well away from the volcano; bring binoculars.

Most photographers will shoot a volcanic eruption from a good distance with a telephoto lens, but others find they get better results by moving closer; this may reduce blurring due to dust and ash and the distortions caused by hot air. It should be attempted only with considerable caution, and only with an expert guide.

Ashfall, volcanic mudflows, and the effects of earthquakes can extend for hundreds of kilometers away from the volcano. The most famous victim of ashfall was the Roman city of Pompeii, buried in 79 CE by Mount Vesuvius. Those two were only about 8 km (5 miles) apart, but ash can also be transported by air in vast quantities over a huge area. The enormous (VEI-8) prehistoric eruption of Yellowstone spread a layer of ash, close to two meters thick in places, over much of the US and parts of Canada and Mexico.

Volcanic ash tends to stop aircraft and vehicle engines, so transportation may be disrupted. An eruption in Iceland in 2010 shut down airports for weeks more than 1,000 km away in mainland Europe, but mostly the affected area is smaller, less than 100 km from the volcano. In some cases, boats and roads may also be shut down.

Dormant volcanoes
When a volcano is dormant, you are mostly safe even close to it, but there are some issues. Lava flows can still be hot for years after an eruption and only a thin crust of rock may be covering them. Old lava flows can be sharp as broken glass, so you should wear hiking boots or very thick shoes. To add to these dangers, lethal gases may be seeping out of vents near the volcano – and some can have a new eruption without much warning.

Lahars can also occur around dormant volcanoes, whenever a deposit of volcanic ash gets wet. They can travel many kilometers, and be devastating. While there are often some warning signs before eruptions, lahars can have no warning. Watch out for possible lahars when there are heavy rains.

Geothermal areas
Geothermal areas also have hazards. Hot springs and mud pools can be dangerous due to heat, acidity, or poison, so do not go near these areas unless you know for sure that they are totally safe. Geysers are a common feature of major geothermal areas, and can erupt hot water or mud unexpectedly.

Landslides are also common in geothermal areas, as even volcanic rock can become weakened over time. Acidic fumes can seep out of fumaroles (steam/gas vents) or hot springs. Noxious gases can also be encountered coming out of holes in the ground, and the gases can reach dangerous levels in enclosed spaces like caves, manholes, or pool enclosures. Carbon dioxide, which is a byproduct of volcanic activity, is known for going into enclosed spaces and it can kill swiftly with little or no warning.

Destinations
This section lists some of the more active or better known volcanoes in the world today; some of these can still be explored from up close. Wikipedia has lists of volcanoes for various regions, which include many we do not list.

Recently active volcanoes get red markers below; dormant or extinct volcanos get blue markers. Related phenomena, such as geothermal areas without actual volcanoes, get black markers.

Ethiopia
The Danakil Depression, part of the Great Rift Valley, has some unearthly landscapes, several geothermal areas and two volcanoes. This is also an important area for paleontology with some man-made tools over three million years old.

Islands near Africa
Madagascar has several volcanic fields but has not had an eruption since 6050 BCE.

Asia
Asia has many volcanoes which are part of the Pacific Ring of Fire, plus some others.

Indonesia
With 167 known active volcanoes, Indonesia is the world's most volcanic country by far. The Volcanological Survey of Indonesia (website in Indonesian) is the government agency responsible for monitoring and warnings.

Philippines
The Philippine Institute of Volcanology and Seismology lists 24 volcanoes as "active"; 21 of those have erupted in the last 600 years. Another 25 are listed as "potentially active" and 355 as "inactive".

The four most active, in order, are: Except for Kanlaon, these are all in southern Luzon.

Other volcanoes include:

Russia
Kamchatka, Russia's largest Pacific peninsula, has several active volcanoes and some hot springs and geysers.



Two volcanoes, close to each other and to Kamchatka's's capital Petropavlovsk-Kamchatsky, have been jointly designated a Decade Volcano.

The largest area of igneous rock (7 million km2, 3 million mi2) on Earth is the. The eruption, about 250 million years ago, is thought to have continued for about two million years and to have caused the largest extinction event in history.

Atlantic
Most of the ridge is submerged, but parts of it are above water. In the North Atlantic, Jan Mayen, between Greenland and Norway, has the northernmost active volcano on Earth, and Iceland and the Azores are also on the ridge. In the South Atlantic, Ascension, Saint Helena, Tristan da Cunha, Gough Island and Bouvet Island are on the ridge.

The Canary Islands are in the Atlantic but not on the ridge; this article therefore lists them under.

The Caribbean Sea is part of the Atlantic, but this article groups that region's volcanoes under.

Azores
This whole group of islands is of volcanic origin.

Iceland


Iceland has many active volcanoes, among them: Some Icelandic volcanoes are featured in fiction. Snæfellsjökull is in Jules Verne's novel Journey to the Centre of the Earth. Surtshellir has a long accessible lava tube, supposedly once home to the fire giant Surtr. Many parts of the Game of Thrones TV series were shot in Þingvellir National Park.

Europe
Culturally and politically, Iceland is part of Europe. Geologically, however, it is part of the mid-Atlantic ridge, so this article lists it under. The Canary Islands are also politically part of Europe, specifically Spain, but this article classifies them geographically and lists them under.

Italy
Both Etna and Vesuvius are Decade Volcanoes.

North America
Most North American volcanoes are in the Pacific Coast Ranges, part of the Pacific Ring of Fire.

USA
The Aleutian Islands and the associated Alaska Peninsula are volcanic in origin and have several active volcanoes. The Cascade Range of the Pacific Northwest has active volcanoes, two of which have had major eruptions since 1900: Hawaii also has many volcanoes.

Canada
Canada has no volcanoes which have erupted in the last few thousand years, and only a few which are classed as active; it is thought to have had only about 50 eruptions in the past 10,000 years. However there are many dormant volcanoes, part of the same geological system that produces active volcanoes in Washington, Oregon and Alaska.

Central America and Caribbean
Many of Central America's volcanoes are part of the Pacific Ring of Fire, but a few in Central America and all of the Caribbean's form another active zone.

Guatemala
Lake Atitlán is spectacularly beautiful and is one of the country's main tourist destinations. There are several volcanoes among the hills around the lake: Another major tourist destination is Antigua Guatemala. There are several volcanoes nearby and guided hikes are available from the town to any of them.

The country also has several other volcanoes.

Oceania
The Pacific Ring of Fire runs through parts of Oceania, and other areas such as Hawaii also have volcanoes.

Hawaii
The entire Hawaiian island chain is volcanic in origin. Most of the volcanoes are of the shield volcano type, spread out rather than sharply conical



Antarctica
Over 130 volcanoes have been discovered in the frozen wastelands of Antarctica, and with many erupting underneath the dense ice sheets they are not particularly practical to visit.



Travel agencies
In many areas &mdash; at least the Philippines, Italy and Costa Rica &mdash; many local travel agencies offer guided tours to their region's volcanoes. There are also agencies that specialize in volcano tourism.
 * Volcano Adventure Indonesia, Sukapura, Indonesia, tel. +62-335-581439, +62-81319090225. Tours to Mount Bromo and elsewhere in Indonesia.
 * VolcanoDiscovery, Germany, tel., . This tour operator specializes in international volcanoes and one of its most important programs is for Indonesian volcanoes. The tours are trekking & photography tours with small groups and an intensive personal service. The tours are usually about 7–14 days.