Top 5 Volcanic Eruptions

Most of us don't live near enough to volcanoes to think about them on a regular basis, but some scientists have spent a lot of time studying them and trying to understand their fickle ways. These days, we can often see the bad news coming, since most volcanoes send off a few warning shots before they erupt. That's a good thing, too, because when they blow go ... get out of the way!

No. 1 - Unzen, Japan

 

Mount Unzen's biggest eruption happened way back in 1792, when, along with a related tsunami, it killed 15,000 people. The Japanese volcano was largely quiet for the next 200 years or so. And then Unzen began to rumble. It started to ooze lava a couple weeks before it violently erupted in 1991, killing 43 people, including a group of scientists and reporters, and forcing the evacuation of thousands of homes. It remained active, releasing lava and ash until about 1995. Since then, it's been getting some much-needed rest.

No. 2 - El Chichon, Mexico

How about a swim in a mountaintop lake? When El Chichon erupted in 1982, it killed 2,000 nearby residents in Chiapas, Mexico, and left behind a brooding, sulfuric, acidic lake that formed when the dome collapsed into a crater and filled with water. Probably not something you'd want to take a dip in. What's worse, no one saw the eruption coming. Most people thought that the volcano had long ago gone extinct, so when El Chichon belched out a "hello," it was quite the unpleasant surprise. Like other large volcanic explosions, the ash sent into the atmosphere had a worldwide atmospheric effect, leading to cooler temperatures across the globe, along with a nice bonus in the form of some particularly colorful sunrises and sunsets.

No. 3 - Mt. Pinatubo, Philippines

The 1991 eruption of Mount Pinatubo, in the Philippines, was the second largest eruption of the 20th century, with a volcanic explosivity index rating of 6. That puts it somewhere in Krakatoa territory: bigger than Mount St. Helens' in 1980, but smaller than Tambora in 1815. (You know, for those of you who follow this volcano stuff.) Pinatubo finally exploded on June 15, tossing out some two and a half cubic miles of material, including rock, ash and toxic fumes. Some 800 people died as a result of the eruption, which left a mile-wide crater lake at the summit.

No. 4 - Mount St. Helens, United States

The May 18, 1980, explosion of Mount St. Helens was the United States' deadliest and most destructive volcanic event, with 57 lives lost. The massive eruption, complete with a 15-mile-high ash plume, was preceded by a 5.1 magnitude earthquake, which caused a large chunk of the mountain to slide away. The volcano erupted violently for nine hours, taking Mount St. Helens from a symmetrical, dome-shaped, snow-capped peak to a topless mountain sporting a massive crater. Quite the makeover. The volcano has continued to belch steam and even magma since the eruption as it slowly rebuilds its dome. As for another big eruption in the future? We've got our eye on it.

No. 5 - Nevada del Ruiz, Colombia

When this Colombian volcano erupted in 1985, it killed 23,000 in the nearby village of Armero, making it the second deadliest volcanic eruption in the 20th century. Many were asleep during the nighttime eruption, which triggered a destructive mudslide-like flow of lava, mud and volcanic debris known as a lahar, amplified as the mountain's glaciers melted. And make no mistake, This volcano was a repeat offender, having taken out villages more than once during eruptions over the past several hundred years. Today, Nevada del Ruiz still poses a threat and thus retains its old nickname, "the sleeping lion."