The World's Most Dangerous Volcanoes

Albay, Philippines

Located in the Philippines, Mayon is the most volatile of the nation's 22 currently active volcanoes. It is a stratovolcano that sits, like so many, on the collection of subduction zones and plate boundaries known as "The Ring of Fire". It is a very active mountain -- constantly letting everyone know how temperamental it is. This is actually a benefit, as volcanoes that sit quiet and silent are the one you usually have to worry about. In the case of Mayon, the fact that it lets lots of energy out doesn't fully mitigate its danger. In fact, it caused the evacuation of the region in early 2018 when, after weeks of increasing unrest, it erupted lava 700m into the air and turned the sky black with ash.  

There are 49 eruptions of Mayon in the historical record, with the (so far) most devastating one being the 1814 tragedy (VEI 4) that claimed an estimated 1,200 lives. The eruption destroyed most villages of the Albay and Camarines province. Mayon's perfectly symmetrical cone sits in the middle province of Albay with a population of over 1.2 million people. The current monitoring and response of the volcano is, so far, adequate to protect the lives of the province... the concern comes from comparing Mayon to similiar volcanos such as Pinatubo or St. Helens. If, instead of a summit eruption, a period of inflation leads to a sudden, explosive eruption at one of the fissures on the volcano’s flanks or beyond then the resulting pyroclastic flows could easily travel well past 20km. The current, evacuated danger zone around Mayon is 7km. The potential for catastrophic loss of life is huge.

Decade Volcano

Java, Indonesia

Located on the island of Java, Merapi is the most active of the 129 active volcanoes in Indonesia. It is considered one of the most dangerous volcanoes in the world due to several factors. One is that it sits inside one the most dense populations on the globe. Yogyakarta City has a population of 3 million people and sits only 15 miles away. Another 70,000 people live in the immediate vicinity. Merapi is well known for its pyroclastic flows... flows that can reach speeds of 70mph and can travel as far as 8 miles. These flows can also be re-mobilized as lahars. 

This stratovolcano has had numerous moderate to large eruptions that appear to have started over 400,000 years ago. These eruptions typically begin with pyroclastic flows and are followed by widespread pyroclastic air fall. Typically, smaller eruptions happen every 2-3 years with larger ones having 10-15 years between them. The most notable eruptions on record occured in 1006, 1786, 1822, 1872 and 1930. It has been postulated that the 1006 eruption covered all of central Java with ash and that the devastation possibly led to the collapse of the Hindu Kingdom of Mataram. 

Merapi's type of eruptions are more dangerous than Hawaiian-style, shield volcano eruptions because the magma in stratovolcanoes is charged with gas. As a result, when such magma finds a conduit to the surface, it can build up a sticky, hot, gas-rich plug known as a volcanic dome. The dome can build up higher and higher, and then suddenly collapse under its own weight in an eruption. This creates a very dangerous mixture of hot gas, ash and dome fragments that can flow downhill as much as 5-10 miles. This flow could wipe out anything on ridge tops because of the gas expansion, and could melt glaciers and mix with the meltwater to form very dangerous, hot and mobile lahars. 

Decade Volcano

Naples, Italy

One of the world's most heavily monitored volcanoes, Vesuvius easily perches high in the ranks of world's most dangerous. This is not just because of its status as a very active and alive stratovolcano, but because it sits in the middle of a city of 3.1 million people. Like many stratovolcanos, this one was formed as a result of plate collision... in this case the African and Eurasian plates. One of several volcanoes that form the Camanian volcanic arc, it squats at the southern end of the chain and is the only one of its companions ( including Epomeo and Campi Flegrei ) that has erupted in the last few hundred years as well as being the only active volcano in Europe.

Vesuvius is also one of the most famous volcanoes in history, having been responsible for the nearly instantaneous destruction of Pompeii in 70 AD. The last time it erupted was 1944, causing some minor damage and killing 26 people. The research being done is showing, however, that the next time it erupts it won't be so gentle and that it is overdue for a large event. It has had 42 eruptions of VEI 3 and up and it is capable of much larger as it erupted at a VEI5 in 1631. It sits on top of a layer of magma that measures 154 square miles and thus, scientists think that the next eruption will be an incredibly forceful plinean explosion, marked by flying rock and ash at speeds of up to almost 100 miles per hour. The summit looms a mere 7.5 miles from downtown Naples and any pyroclastic flow from a volcano like Vesuvius would take only about two and a half minutes to travel that distance.

Were Vesuvius simply to repeat the same size eruption that destroyed Pompeii, there could potentially be 6 million people who would lose power, water and transportation - not to mention how many dead in the pyroclastic flows. Vesuvius is intensely monitored because of the high danger, and there would hopefully be many indicators pre-eruption... but as we know from both experience and record, volcanoes are unpredictable.

Decade Volcano

Washington, US

Considered one of the most dangerous volcanoes in the US, Mt. Rainier is also the highest peak in the Cascade mountain range. With an active hydrothermal system and thick glacial layer, it has been the source of countless eruptions and volcanic mudflows (lahars) that have surged down valleys on its flanks and buried vast areas of land... land that is now densely populated. The last magmatic eruption was around 1,000 years ago, but small summit explosions were witnessed in 1894. The real danger of Rainier, however, is its lahar potential. This mountain has 26 glaciers containing more than five times as much snow and ice as all the other Cascade volcanoes combined. If even a small part of this ice were melted by volcanic activity, it would  trigger truly enormous lahars, lahars that would be incredibly destructive simply by the fact of the mountains great height and steepness. 

Mount Rainier has erupted less often and less explosively in recent millennia than its well-known neighbor, Mount St. Helens. However, because of the nearby population centers and the danger posed by catastrophic lahars, its threat level is much higher.

Japan

Located on Kyushu island, Mt. Aso has been active for decades. At approximately 2.2 million years, it is an old volcano that got its start with basaltic eruptions and then formed its major caldera about 300,000 years ago with four huge eruptions, the last being the largest. Since the caldera formed more than 17 new cones have formed inside it. The five main cones are Neko, Taka, Naka-Dake, Eboshi, and Mt. Kishima. Only Naka-Dake is currently active: it has erupted 167 times from seven different craters since 553 CE. Two flank volcanoes, Akai and Omine sit along a fault (Oita-Kumamoto Tectonic Line) extending from the volcano towards Kumamoto City. 

The dangers of Mt Aso are many, which put it high on this list. The first is that Kyushu island is densely populated. With what we know about the type of volcano that Aso is and what kinds of eruptions it is capable of, a large explosion could blast outwards in excess of 50km from the vent, leaving little chance of anything in proximity to the volcano surviving. The second is that Aso's magma reservoir is thought to be "charged" according to researchers. Hopefully Mt. Aso would give its human neighbors some warning as well as time to evacuate, otherwise it could be potentially catastrophic.

Decade Volcano

Democratic Republic of Congo

Nyiragongo is not as well studied, nor monitored as a stratovolcano with its associated hazards should be. Twice in recent history it has had two devastating volcanic eruptions; the first related to its lava lake, and the second from a deadly eruption off its flank. The lava lake itself is somewhat unusual due to the viscosity and high alkalinity of its composition. This allows it to move much more quickly than, say, the lava from a Hawaiian shield volcano... upwards of 60mph. Back in 1977, the crater wall holding the lava lake ruptured and within 30 minutes the entire lake had drained, sending lava flowing to the north, west, and south of Nyiragongo. These lava flows reached up to 62 mph, wiping out several of the surrounding villages and burning almost 300 people alive. 

Because of the proximity of Goma, a city of over a million people, the volcano poses a real danger.  An eruption in Goma itself from fissures located within a mile of the lake shore that could lead to major explosion, and a lava eruption in nearby Lake Kivu could disturb the carbon dioxide and methane stored in the lake at depth which would lead to the release of an asphyxiating gas cloud that could disperse over a wide area. Either one of these events could lead to catastrophic loss of life. 

Unfortunately, the political and humanitarian situation makes it unlikely that the population will heed warnings of an impending eruption and be prepared to evacuate part or whole of Goma as a precautionary measure. Secondarily, the population relies almost entirely on Lake Kivu for drinking water. This reliance is unchanged today and the prevention of enteric disease outbreaks like cholera after a future eruption is a major consideration. These things make Nyiragongo very dangerous indeed.