Worst Volcanic Eruptions

The 1985 Nevado del Ruiz volcanic eruption in Colombia was the worst eruption over the period of last 100 years, wherein as many as 23,000 people lost their lives. And yet, it doesn't even feature in the top three worst eruptions in the history.

While the intensity of an earthquake is measured using Richter magnitude scale, a.k.a. Richter scale, the Volcanic Explosivity Index (VEI) is used to measure the explosiveness of a volcanic eruption. It is an open ended scale which gives the largest volcanic eruptions a magnitude of 8 and non-explosive eruptions a magnitude of 0. The credit for the development of VEI goes to renowned volcanologists, Chris Newhall and Stephen Self.

According to this scale, the explosivity value of a volcanic eruption is determined on the basis of the volume of products, eruption cloud height, type of volcano, etc. Even though its application is quite popular in the field of geology, it will be a bit too harsh on our part to expect a layman to understand the intricacies of the entire process, and thus, it is better to stick to the death toll to determine which eruptions were the worst in history.

For instance, the Mount Pinatubo volcanic eruption, which measured VEI 6, resulted in death of as many as 700 people in Philippines, while Mount Pelée eruption of 1902, which measured VEI 4, killed around 33,000 people on Martinique island in the Caribbean Sea.

The severity of a volcanic eruption depends on several factors including the period of explosion and the region where the volcano lies.

A volcanic eruption with a magnitude of VEI 8 need not necessarily be the worst eruption ever. An eruption with a magnitude of VEI 5 or 6 can create more damage as compared to eruptions with a magnitude of 7 and 8.

4. Nevado del Ruiz 1985 (Colombia):
VEI - 3
Death Toll - 23000

5. Mount Vesuvius 1631 (Italy):
VEI - 4
Death Toll - 18000

6. Mount Unzen 1792 (Japan):
VEI - 2
Death Toll - 15000

7. Mount Kelut 1586 (Indonesia):
VEI - 4
Death Toll - 10000


8. Santa Maria 1902 (Guatemala):
VEI - 6
Death Toll - 6000

9. Mount Galunggung 1822 (Indonesia):
VEI - 5
Death Toll - 4000

10. El Chichón 1982 (Mexico):
VEI - 5
Death Toll - 3500

While these were the worst eruptions which were recorded by volcanologists, there have been more severe eruptions which probably killed millions of people in one go.

Among these, one of the best example is the Laki eruption of 1783 in Iceland, which is estimated to have killed over six million people. The only reason why 1783 Laki eruption, Lake Toba eruption, or the Minoan eruption don't make it to this list, is because their death toll is based on estimates.