The Most Dangerous Volcanoes on the Planet

Iceland is often called the Land of Fire and Ice. Technically the only part of the Mid-Atlantic ridge that breaks above the ocean’s surface, it is covered in active volcanoes and other geothermal features. Hekla is a stratovolcano, also known as a composite volcano. It’s part of a 25 mile-long volcanic ridge and has multiple active craters. It is known to have erupted more than 20 times over the past 2,000 years and continues to spray tephra (ejected rock particles) around Iceland and beyond.

Mount Agung, on the Indonesian island of Bali, and is currently active. It is the highest point on the island and, most recently, has erupted several times between 2017 and 2019. Volcanic earthquakes were observed leading up to the eruptions and nearby homes were evacuated before the event. After a considerable number of earthquakes, the volcano began to erupt and spew ash into the air, disrupting air traffic. Pyroclastic debris flows (composed of gasses, ash, and rocks) were spotted coming off the mountain, but no one was hurt, as they’d already been evacuated.

The Okataina volcanic center on New Zealand’s North Island is an area that has multiple recently active volcanic vents. The center includes several large volcanoes that experts believe will erupt again. All three of the peaks of one of the volcanoes, Mount Tarawera, exploded in 1886. The nearby area was sparsely populated but the explosions still killed over 100 people in a nearly four-mile radius. The area has not had any major eruptions since 1886 but the center is still considered active.

Mount Etna, on Sicily’s eastern coast, is one of the tallest active volcanoes in Europe. It lies in the area where the Eurasian and African tectonic plates meet. It has been almost continuously active at least since ancient times — according to Greek mythology, an ancient monster was said to be trapped inside it — and has had six summit eruptions and four flank eruptions in the past 20 years alone. Few people have been recorded killed by Etna over the years, but it has destroyed several nearby towns.

Grímsvötn has erupted more often than any other volcano in Iceland. It is situated under a glacier, and the reactions between lava and meltwater under the glacier can cause violent explosions. These explosions and other activity can lead to glacial bursts — sudden powerful floods affecting nearby areas. Eruptions from the volcano in 2011 spewed ash into the air and disrupted some European air traffic. The Icelandic Meteorological Office has warned that another eruption might be imminent.

Kilauea is a shield volcano on the Big Island of Hawai’i, one of many in the archipelago that are active today. Kilauea has been active in several different ways. From 2008 to 2018 its crater had an active lava lake and there were near constant eruptions from vents on its eastern side. In 2018, activity shifted to a different part of the volcano and destroyed several nearby towns.

Masaya Volcano lies a little more than 10 miles from the outskirts of Managua, Nicaragua’s capital. It is a complex volcano made up of several nested calderas and craters. In the last 20 years, several smaller explosions have sent debris flying from the volcano, causing damage to nearby cars and structures. The volcano remains active but has mostly just let off volcanic gases and had several small explosions in recent years. In 2020, daredevil Nik Wallenda walked on a steel cable over one of the volcano’s calderas.

The eruption of Vesuvius and subsequent destruction of Pompeii is perhaps the most famous historical account of volcanic destruction. In the year 79, the mountain was ripped open by an explosion more powerful than that caused by some atomic weapons. Pompeii, along with several other cities, was rapidly buried under pyroclastic surges and ash. The speed of the event left many victims preserved as they had been moments before the eruption. The volcano continues to wreak havoc and is considered extremely dangerous because of the large population in nearby Naples and other settlements.

Krakatau — also called Krakatoa — is a caldera volcano in the Sunda Strait between the islands of Java and Sumatra, part of the Krakatau Archipelago. The volcano is famous for a violent eruption in 1883 so powerful that it was heard as far away as New Zealand and western Australia. The eruption and the ensuing tsunamis caused massive destruction and reportedly killed over 35,000 people in the region. (a 1968 movie about the eruption, “Krakatoa, East of Java,” had geographers scratching their heads: Krakatoa is actually west of Java.) The volcano remains active, with smaller eruptions throughout the 2010s.

The town of Rabaul is built on a bay, surrounded by rising hills. While this may look like a protective place for a settlement, the bay is actually the bowl of the Rabaul volcano. The town was decimated by an eruption in 1994 that sent ash falling throughout the harbor and destroyed a large number of structures. The town remains inhabited and has been partially rebuilt but is considered to be in danger of being destroyed by future volcanic activity.

Santa Maria erupted massively in 1902 for the first time in recorded history. The event was one of the three largest eruptions of the 20th century, killing more than 6,000 people. Locals didn’t recognize the signs of an impending eruption since the volcano hadn’t previously been known to be active. A smaller volcanic event in 1929 produced deadly pyroclastic flows, and it has continued to see less violent activity in recent years, including lava flows.

Aira is a massive caldera on the southern end of Japan’s Kyushu island. Currently, the city of Kagoshima, situated in the middle of the caldera that forms a scenic bay, is home to over 900,000 people. Japan’s most active caldera, Aira sees several small eruptions every year. Mindful of their precarious position, residents have put in place one of the most advanced seismologic monitoring systems in the world. They are also well-trained in evacuation procedures.