On Saturday, Mount Nyiragongo in the Democratic Republic of Congo erupted suddenly, sending lava cutting a path of destruction and forcing thousands of residents to evacuate. According to the UN refugee agency UNHCR, 32 people have been killed.

Three days later, Mount Etna in Italy erupted for the fourth time in six days, shooting magnificent lava fountains and plumes of smoke into the air.

There are about 1,500 active volcanoes scattered around the world, as well as countless others on the ocean floor. Seventy-five percent of Earth's on-land volcanoes are concentrated near the Ring of Fire around the Pacific Ocean where several tectonic plates converge. 

Here are five of the deadliest volcanic eruptions in history:

1. In 1815, in the largest recorded volcanic eruption in history, Mount Tambora in Indonesia exploded and killed over 90,000 people, contributing to a global climate anomaly named "a year without summer" in 1816 and causing the worst famine in the 19th century. The mountain, which used to be about 4,300 meters high and ranked among the highest peaks in Indonesia, lost about one third of its height and was reduced to about 2,850 meters.

2.Over half a century later, also in Indonesia, the eruption of a volcano in 1883 destroyed over 70 percent of Krakatoa island and its surrounding archipelago. Over 35,000 people lost their lives. The eruption was so violent that even people in west Australia, thousands of miles away, heard the sound. The tsunami it triggered even rocked the sea near South Africa and bodies of victims were found floating in the ocean for months after the event. 

3. On May 8, 1902, within just a few minutes, an infernal blast of hot gas and volcanic debris obliterated Saint Pierre – once the most important city in France's Caribbean overseas department of Martinique, leaving only a handful of survivors in its population of about 30,000. The worst volcanic unrest in the 20th century of Mount Pelee started with bad omens including small tremors and eruptions, which were not taken seriously until the devastating blast. Mount Pelee remains active and is being closely watched by geophysicists and volcanologists. 

4. Mount Ruiz in the southern American country of Colombia was noted for two eruptions in 1985 when a mixture of mud, ash and water with a crest of 4.5-15 meters raced down the volcano's eastern slope. Torrents of mud almost totally buried the town of Armero, killing about 25,000 people. The volcano remains active with the latest eruption recorded in 2018.

5. It's hard to imagine that volcanic unrest in southeast Asia, thousands of miles away, contributed to the deaths of tens of thousands of people in the UK. But it's true. These two events were linked. The catastrophic eruption at the Samalas volcano in Indonesia created an eruption column reaching tens of kilometers into the atmosphere. Its impact was felt in Europe as the ashes blocked the sun, causing low temperature and crop failure. In London, the resulting famine killed about 20,000 people.

Casualties from volcanic eruptions in the 21st century have been greatly reduced, with the deadliest claiming over 400 lives in 2018 in Indonesia. But volcanic eruptions remain one of the deadliest of all natural disasters in the world.

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About 'Natural Phenomena'

The series "Natural Phenomena" takes you to an unknown world of natural forces. From natural disasters such as earthquakes and volcanic eruptions to spectacles like aurora and mirage, let's dig into the secrets of our planet.

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