Contrary to popular belief, volcanoes aren’t found where tectonic plates slide past each other, but they’re typically found where these plates converge and diverge.
A volcanic eruption is one of nature’s most violent occurrence, having potentially catastrophic effects, from dropping the Earth’s temperature, to wiping out entire nations. The following list includes the top 10 worst volcanic eruptions in human history, measured by the Volcanic Explosivity Index (VEI). This scale is, in some ways, similar to the magnitude scale for earthquakes.
Developed in the 1980s, VEI uses factors like the rate of an eruption, its volume and other variables to quantify its power. The VEI scale rates eruptions from 1 to 8, each VEI being 10 times greater than the preceding one. Although there were no VEI-8 eruptions in the past 10,000 years, human history has seen some violent and devastating volcanic eruptions. The below listed volcanoes erupted in the last 4,000 years, within human records, and are ranked according to their strength.
1. Huaynaputina, Peru, 1600 – VEI 6 - Regarded as the most powerful volcanic eruption in South America, in history, it sent mudflows as far as the Pacific Ocean, 75 miles (120 km) away. The explosion also caused the climate to cool down, as the summers following the 1600 volcanic eruption were the coldest in 500 years. The effects of this eruption are seen today as well, as a 20-square-mile (50-square-km) area west of the mountain is still covered in ash.
2. Krakatoa, Sunda Strait, Indonesia, 1883 – VEI 6 - The Krakatoa stratovolcano erupted after weeks of rumblings, on April 26-27, ejecting enormous amounts of rock, ash and pumice. The eruption completely destroyed the island that was once home to the Krakatoa, although new eruptions (as of December 1927) built Anak Krakatoa (“Child of Krakatoa”).
The powerful explosion also caused a tsunami with waves with heights of up to 120 feet (40 meters) and killed 34,000 people. The increase in wave heights were registered all the way on the Arabian Peninsula, 7,000 miles (11,000 km) away.
3. Santa Maria Volcano, Guatemala, 1902 – VEI 6 - This eruption came after a period of about 500 years in which the Santa Maria lay dormant. The explosion is one of the largest of the 20th century, causing a crater nearly a mile (1.5 km) across on the left flank of the mountain. Santa Maria erupted again in 1929, releasing pyroclasitc flow that caused the deaths of 5,000 people.
4. Novarupta, Alaska Peninsula June, 1912 – VEI 6 - Part of the Pacific Ring of Fire, the Alaska Peninsula is home to a chain of volcanoes, but the Novarupta eruption was one of the largest of the 20th century, sending over 3 cubic miles (12.5 cubic km) of magma and ash into the air. An area of 3,000 square miles (7,800 square km) was covered by ash more than a foot deep.
5. Mount Pinatubo, Luzon, Philippines, 1991 – VEI 6 - The Pinatubo eruption is considered the best example of an explosive eruption of a stratovolcano. It threw more than one cubic mile (5 cubic km) of material, creating a 22-mile (35 km) column of ash that fell on the countryside causing some roofs to collapse under the weight. The eruption also released millions of tons of sulfuric dioxide and other particles that, after being spread around the world through air currents, caused the global temperature to drop by one degree Fahrenheit (0.5 degrees Celsius), over the next year.
6. Ambrym Island, Republic of Vanuatu, 50 AD – over VEI 6 - The small volcanic island, of just 257-square-miles (665-square-km), witnessed the most impressive eruptions in human history. The explosion spewed a wave of hot ash and dust down the mountain, causing a caldera 7.5 miles (12 km) wide. The volcano was among the most active in the world.
7. Ilopango Volcano, El Salvador, 450 AD - over VEI 6 - Although Ilopango is located fairly close to the capital city of El Salvador, San Salvador, it has only erupted twice. The very first eruption covered most of the central and eastern part of the country in ash and pumice, destroying early Mayan cities. Some of El Salvador’s largest lakes are located in its caldera.
8. Mt. Thera, Island of Santorini, Greece, ~1610 B.C. – VEI 7 - According to geologists, Thera erupted with the power of several hundred atomic bombs, compressed in less than a second. It is strongly believed that, while Santorini residents might have suspected that the volcano might erupt and fled the area, the massive eruption caused severe tsunamis, released massive amounts of sulfur dioxide and altered the climate.
9. Changbaishan Volcano, China/North Korea border, 1000 A.D. – VEI 7 - The eruption of the Changbaishan Volcano released volcanic materials as far Japan, 750 miles (1,200 km) away. It created a caldera about 3 miles (4.5 km) across and roughly half a mile (~1 km) deep at the summit. Today, it is home to some of the most visited lakes in the region, Lake Tianchi and Sky Lake.
10. Mt. Tambora, Sumbawa Island, Indonesia, 1815 – VEI 7 - The Tambora eruption is the larges volcano explosion ever recorded, ranked as a VEI 7 (“super-colossal”). On April 1815, Tambora’s explosion was so loud it was heard over 1,200 miles (1,930 km) away in Sumatra Island. It is estimated that the eruption claimed the lives of 71,000 people. The Tambora volcano is still active today.