The World’s Most Dangerous Volcanoes

On the morning of August 27th 1883 the small Indonesian island of Krakatoa virtually destroyed itself in a series of cataclysmic explosions the likes of which have never been witnessed in human history before or since. Not only was the explosion the loudest sound ever recorded, it released 4 times more energy than the most powerful nuclear weapon ever created, the Tsar Bomba. In fact the sound of Krakatoa going off was heard 4,830 km (3,000 miles) away and ruptured eardrums 64 km (40 miles) away.
It is estimated that anywhere between 35,000 and 120,000 people died as a result of the Krakatoa eruption. Most of these were as a result of tsunamis caused by the volcano, however around a thousand died in Ketimbang in Sumatra as a direct result of the eruption.

Today there are around 1,500 active volcanoes around the world, Anak Krakatau, “the Child of Krakatoa”. Most of these are located around the Pacific “Ring of Fire” including the biggest, Mauna Loa in Hawaii. However, there are plenty of notable exceptions including some of the most dangerous active volcanoes on earth.

Before heading to the list it is worth mentioning the scale by which volcanic eruptions are measured, the Volcanic explosivity index (VEI). This ranges from 0 to 8 with Krakatoa only scoring 6 or “colossal”. A score of 8  is described as “apocalyptic”. The good (or maybe bad) news is this hasn’t happened for nearly 25,000 years when Taupo in New Zealand blew.

10. Ulawun, Papua New Guinea

Ulawun volcano, Papua New Guinea

Ulawun volcano (and friends) from space

Ulawun is the classic cone shaped volcano with its smoking peak rising up out of the jungle. But it isn’t just jungle surrounding this active volcano, there are also several thousand people living within the vicinity.

Known locally as the “Father”, Ulawun is Papua New Guinea’s most active volcano and probably the most dangerous. One of the major risks posed by the volcano is slope failure. Given its height some have suggested it may be relatively unstable meaning an eruption could result in massive landslides which would devastate the surrounding area and result in the loss of many lives.

But it isn’t just the possibility of Ulawun erupting that is a reason to be wary of this volcano. It is estimated that Ulawun belches out almost 2% of all the world’s sulphur dioxide, a noxious pollutant.

9. Popocatepetl, Mexico

Popocatepetl, Mexico

Popocatepetl, Mexico

Not only is the snow-capped Popocatépetl the second highest mountain in Mexico, it is also a highly active volcano. What is most alarming about this enormous, smoke and fire belching stratovolcano is its proximity to the Mexican capital. Popocatépetl is only 70 km (40 mi) from Mexico City which is home to 18 million people. But it gets worse; the city of Puebla which is home to 2 million people is even closer. A major eruption here would be catastrophic with molten lava and mudslides flowing into the surrounding valleys and millions within the blast radius.

During the last 500 years there have been more than 15 major eruptions of Popocatépetl with the most recent in 1947. So there is plenty of previous form. Whilst things were relatively quiet activity seems to have picked up over recent years with rumblings in 2000 sparking a mass evacuation and any number of small eruptions since.

8. Mauna Loa, Hawaii

Mauna Loa is purported to be the largest active volcano on Earth. There is more lava bubbling away under this behemoth than any other volcano. Mauna Loa’s size is not entirely obvious from the 4,170 m (13,680 ft) peak but when you take into account that it rises up from the sea floor it is actually taller than Mount Everest.

As a shield volcano Mauna Loa is a bit of a gentle giant. Instead of exploding dramatically these volcanoes tend to spew out constant streams of magma forming shallow slopes. These lava flows are generally slow moving and possess little danger, except to property.

So why, I hear you ask, is Mauna Loa on this list of the World’s most dangerous volcanoes? Well, there is a Doomsday scenario. This huge volcano has grown rapidly of the millenia and there may be deep fault lines within the slopes of this sea mountain. A collapse and resulting massive landslide could cause a megatsunami. That’s right, a mega-tsunami! You may think this far-fetched but there is geological evidence of this sort of collapse 100,000 years ago causing a 1,000 ft (300 m) wave which piled into the island of Lāna`i. If the same were to happen at Mauna Loa, a tsunami would arrive in Honolulu within 30 minutes reaching as far as 16 miles (22 km) inland.

7. Yellowstone Caldera, USA

Yellowstone supervolcano

Hot springs at the Yellowstone Caldera

Now, the Yellowstone Supervolcano is a tricky one. It might be best placed at the top of this list or not on the list at all, nobody seems to know for sure. Given what it is and previous form the potential is pretty terrifying – think something along the scale of a nuclear war. Many of the largest volcanic eruptions ever took place in this region including one that was equivalent to a 250,000 megaton explosion – that’s over 1,000 times bigger than Krakatoa. During this eruption 1,200 cubic miles (5,000 km3) of rock was ejected, enough to fill Lake Michigan. What is more, so mush ash would be created that the entire USA would have been buried under a 10 feet (3 m) carpet making it uninhabitable, whilst the rest of the world would be starved of sunlight for months.
Fortunately, this all happened 27 million years ago.

Today the caldera measures around 40 miles (60 km) across, but it is what is underneath that gives cause for concern. It is estimated that there is a magma chamber measuring 50 miles (80 km) long and 12 miles (20 km) wide lurking beneath Yellowstone. That is huge, and is certainly on the supervolcano scale. However, whilst some media sources have claimed the next supereruption is now overdue scientists seem to dismiss this stating that such events are neither “regular or predictable”.

6. Sakurajima, Japan

Sakurajima volcano, Japan

Sakurajima volcano.
Photo: Kimon Berlin / License

Sakurajima in southern Japan is sometimes referred to as the “Vesuvius of the East” on account of its highly active nature. The similarities don’t end here either; located just a few miles away is the city of Kagoshima which is home to nearly 700,000 people. If there is a city anywhere that has prepared itself for the danger of an imminent volcanic eruption then it is Kagoshima. There are regular evacuation rehearsals and the city even has volcano shelters.

But this isn’t just for fun. Sakurajima is constantly throwing out columns of ash high into the atmosphere with thousands of minor explosions every year. So active is the volcano that it is one of only three volcanos to be placed on Level 3 (orange) alert. This means don’t get too close.

In a recent daytime eruption so much ash was ejected that it threw the Kagoshima city into darkness. However, this was nothing compared to an eruption in 1914 in which the former mountain island spewed out so much lava that it became part of the mainland.

Whilst on the subject of Japan it is worth pointing out that the iconic Mount Fuji is not just the country’s highest mountain, but an enormous volcano within 60 miles (100 km) of Tokyo…

  • GR

    I have just returned after a trip to Vesuvius. I thoroughly advise people to pop up and peer into the crater!