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.
Volcanic eruptions are not all that common — a few dozen a year, worldwide — and 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 in close proximity to a volcano.
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, Mount Etna and Kilimanjaro, are of this type. Filipino tourist literature claims their Mayon Volcano has the world's most perfect cone.
A complex stratovolcano has multiple cones and/or multiple calderas; examples include 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.
According to the Smithsonian Global Volcanism Program, the major volcano monitoring organization based in Washington, DC, volcanoes can be classified as follows:
active if
dormant (French for sleeping) if it is active but not currently erupting
extinct if it is no longer active Other organizations generally use the same terms, but may have somewhat different definitions. These definitions 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.
Decade Volcanoes. These are 16 active volcanoes selected by scientists as particularly worthy of study because they both have a history of large eruptions and are located near populous areas. These may be the most dangerous volcanoes on Earth in terms of potential to create large disasters. 2020-05-04
Pacific Ring of Fire. This is a group of active tectonic areas, including many volcanoes, running around the Pacific Ocean. On the east, this means the Andes and the Rocky Mountains. On the west, the ring runs through Russia's Kamchatka, Japan, the Philippines, Indonesia and all the way to New Zealand. 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.
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 km<sup>3</sup> of ejecta, VEI-6 10 km<sup>3</sup>, VEI-7 100 km<sup>3</sup>, and VEI-8 1000 km<sup>3</sup>.
Really large eruptions are quite rare. The 20th century had three VEI-6 eruptions, ten VEI-5, and hundreds of smaller ones, but none of VEI-7 or above. As of late 2022, the 21st century has had two VEI-5 or 6 events and nothing larger. The most recent VEI-7 events were 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.
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 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.
Supervolcanoes are generally in the form of large calderas (Spanish for "cauldron"), 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, 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.
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 640,000-year-old caldera. New Zealand, with its volcanoes in the North Island, is also known for extensive geothermal areas, with Rotorua perhaps being the best known one. Geysir in Iceland, which is the namesake for all geysers in the world, is another famous geothermal region. The 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.
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 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 — perhaps earth tremors or expelling steam or dust — it may be wise to consider leaving the area without waiting for an evacuation order.
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. If you want to go anywhere near an erupting volcano, then a guide is absolutely essential. 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.
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, but some use construction boots with steel in the toes and soles, and some choose lighter shoes for comfort. In any case, look for thick soles, preferably in a material such as Vibram which does not melt easily.
Other equipment — such as heavy work gloves, a helmet, safety googles, a walking stick, a facemask for dust and a gas mask for poisonous fumes — may be 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.
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.
Volcano hazard zones can extend for dozens of kilometers, and there are multiple hazards:
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.
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, preferably 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 most 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.
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 can have hazards similar to those of volcanoes due to geological mechanisms. 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.
A selection of some of the more active and/or better known volcanoes in the world today. Some of these can still be explored from up close.
Mount Cameroon (Mongo ma Ndemi), 4.216667°, 9.1725°. The only volcano outside of Europe to have records of an eruption before the Common Era in 5 BCE. It remains active today: its most recent eruption was in 2012. Near the city of Buea.
Mount Kilimanjaro, -3.075833°, 37.353333°. This peak in Tanzania is Africa's tallest at 5895 m (19,340 ft). It has a series of concentric summit craters apparently less than 10,000 years old and may have last erupted less than 2000 years ago. The name Kilimanjaro means "shining mountain" in Swahili, no doubt due to the once-extensive glaciers which are unfortunately disappearing rapidly each year.
Mount Nyiragongo, -1.516667°, 29.25°. In Virunga National Park in the far eastern D.R. Congo, near Goma and the Rwanda border. One of just four volcanoes in the world with a persistent lava lake, the others being Erta Ale (Ethiopia), Kilauea (Hawaii), and Mount Erebus (Antarctica). The volcano is usually accessed by overnight hike (8–10 hr up first day, hike down the following morning), with the night spent in tents on the rim of the caldera with stunning views of the lava lake and the surrounding region. Unfortunately, it is located in a conflict zone and access is occasionally blocked due to the presence of rebels and criminal gangs. It is a Decade Volcano.
Ol Doinyo Lengai ("Mountain of God" in the Masai tongue), -2.764444°, 35.916111°. In Ngorongoro Conservation Area in Tanzania, this is the only volcano on Earth that erupts natrocarbonatite lava. This type of lava emerges black, cools to grey, and oxidizes to white.
Volcanoes National Park, -1.48°, 29.53°. This park in Rwanda is famous as the home of mountain gorillas. Visiting requires an advance reservation, an expensive permit, and some hiking.
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.
Mount Aso, 32.8844°, 131.1039°. This is one of the largest active volcanoes in the world with the largest caldera.
Mount Fuji, 35.360628°, 138.727365°. Located near Tokyo, this is Japan's highest and most beautiful volcano. It is also the most climbed mountain in the world and a place of religious significance in Shinto worship.
Mount Daisen, 35.371111°, 133.546389°. A dormant stratovolcano, also significant in Shinto.
Sakurajima, 31.580556°, 130.658056°. This is an active volcano just outside of Kagoshima. It is a Decade Volcano.
Mount Unzen, 32.761389°, 130.298611°. This is a complex stratovolcano. It is a Decade Volcano.
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:
Other volcanoes include:
Kamchatka, Russia's largest Pacific peninsula, has several active volcanoes and some hot springs and geysers
Nisyros, 36.583333°, 27.166667°. This island in the Greek Dodecanese islands is the top of a volcano, mildly active with smoking fumaroles. It is possible to walk into the crater floor for a closer look.
Santorini, 36.4067°, 25.4333°. This island in the Aegean Sea is the largest of a ring of islands around an ancient caldera, and probably Greece's most famous volcano. It had a VEI-7 eruption around 1600 BCE. Some historians suggest the associated tsunami and earthquakes destroyed the Minoan civilization on nearby Crete, or that the devastation of these islands is the origin of the Atlantis myth, but both those theories are quite controversial.
The volcano is still active, for it last erupted in 1950 out of Nea Kameni ("New Burnt" in Greek), an island made up of lava flows in the middle of the caldera bay. It is the country's only Decade Volcano.
Iceland 📍 has many active volcanoes, among them Hekla, Katla and Askja. In medieval times Hekla was thought to be a gateway to Hell. It has had five eruptions since 1947 (the last being in 2000), and is regarded as unpredictable. A volcano below the Eyjafjallajökull glacier famously disrupted European air travel for days with an ash cloud released during an eruption in 2010.
Some Icelandic volcanoes are featured in fiction. Snæfellsjökull is in Jules Verne's novel Journey to the Centre of the Earth and many parts of the Game of Thrones TV series were shot in Þingvellir National Park.
Canada has no active volcanoes and is thought to have had only about 50 eruptions in the past 10,000 years. However, the Canadian Rockies include many dormant volcanoes; geologically they are part of the same system that produces active volcanoes in Washington, Oregon and Alaska.
Cotopaxi, -0.68°, -78.438°. One of South America's most spectacular volcanoes.
Arenal. This is the youngest volcano in Costa Rica. Its eruptions were frequent until 2010, but now it is calm. Several companies in nearby towns offer tours.
Galeras. A Decade Volcano.
Volcan Santa Maria and Volcan Santiaguito in Guatemala, near Quetzaltenango.
Volcan de Fuego, Acatenango and Volcan Pacaya in Guatemala, near Antigua Guatemala. Guided hikes are available from the town.
Volcan Atitlan, Volcan San Pedro and Volcan Toliman in Guatemala, on the southern shores of Lake Atitlán.
Volcan Láscar in the Atacama Region of Northern Chile.
The Volcanoes of Concepción (active) and Maderas (dormant) that form the island of Ometepe , Nicaragua
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
Kilauea, 19.397°, -155.29°. This volcano has been erupting continuously out of its flank vent, known as Pu'u O'o ("Hill of the O'o bird" in the native Hawai'ian language) since 1983. You can normally peer safely into its magma chamber from an observation point a couple of miles away in Hawaii Volcanoes National Park after nightfall.
Mauna Loa, 19.479444°, -155.602778°. Hawaii's highest historically active volcano, topped by the Moku'aweoeo Caldera. It is also the largest volcano by volume in the world. Don't be fooled by its gentle slopes – with its highest point at 4170m/13,683 ft) and the summit often covered in snow during the winter, the climb can be both difficult and dangerous for inexperienced hikers, and altitude sickness is a hazard for almost anyone. It is Hawaii's only Decade Volcano.
Its most recent eruption was in November and December 2022.
Mauna Kea. This is the highest volcano in Hawaii at 4205 m (13,796 ft), and is pockmarked with cinder cones. Its high elevation is a magnet for astronomers with their giant telescope facilities, and even skiers. It is a dormant volcano; its last eruption was about 2460 BCE.
Haleakala (East Maui volcano). This is the tallest volcano on the island of Maui and makes up most of the island. It is renowned for its erosional crater and the cinder cones nestled inside. The name means "House of the sun" in Hawai'ian. There is a Haleakalā National Park around it.
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.
In many areas — at least the Philippines, Italy and Costa Rica — 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. +49 2241-2080175 , +30 2107522310 . 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.