The violence and size of a volcano’s eruption is expressed by the Volcanic Explosivity Index (VEI). Values for the VEI range from 0 to 8, and are based on: 1. the volume of material (lava and particles) erupted 2. the height of the eruption column 3. how long the eruption lasts The larger the VEI value, the larger the eruption. • • • • • Mt. Vesuvius, the active volcano that looms over the Bay of Naples in southern Italy, has erupted well over 30 times that we know of. In A.D. 79, when a two day eruption of lava and ash covered the cities of Pompeii and Stabiae in ash. The ash left behind solid rock casts of its victims. The temperature of the eruption was under 200°, therefore, people here suffocated and were then buried in the violent ash. The total number of Vesuvius' victims will most likely never be known, but archeologists are aware of at least 1,000. The city of Herculean was hit suddenly by the pyroclastic flow while waiting to escape in Herculaneum the boat house. There bones The Eruption of Mt. remain where they died in second hundreds of years ago. Vesuvius 79AD Herculaneum • • • • Mount Pelée, standing more than 4,500 feet high on the French Caribbean island of Martinique, erupted violently in May 1902, killing nearly 30,000 people — effectively the entire port city of St. Pierre. The catastrophe was so devastating that the term nueer dante or glowing cloud that is now known as a pyroclastic flow. There had been warnings of steam, light earth shocks and raining ash, but they were ignored. After the town was wiped out, Pelée went dormant for some months, until geologists discovered a lava dome, dubbed the tower of Pelée, that rose to more than 1,000 feet above the crater floor before eventually crumbling in March 1903. 25 year old Louis Auguste Cyparis a convicted felon who injured his friend with a glass during the bar fight. Interestingly, Louis escaped the jail night before the eruption, but he reported himself to the jail the very next morning. He survived because his dungeon cell had poor ventilation. • • • • • In 1883, the volcano on the Indonesian island of Krakatoa erupted with 13,000 times the power of an atomic bomb. The sound of the spewing smoke and rock was reportedly heard thousands of miles away, as far as islands off the eastern coast of Africa. Hundreds in a nearby Sumatran town died almost instantly when by the pyroclastic flow that was so powerful that it moved over the ocean to incinerate other islands A 100ft tsunami was generated as the massive earthquakes from the eruption caused 1/3 of the island to crumble into the sea. An estimated 36,000 or so perished in total. Krakatoa itself then slumped into the boiling depths of the ocean, but a new island at the site was spotted in 1927, and it still occasionally spits lava into the sky. It's been dubbed Anak Krakatoa, or Child of Krakatoa. Anak Krakatau • • • • When Mount Pinatubo erupted in 1991, the amount of sulfuric gas and ash it sent into the stratosphere cooled global ground temperatures by 1°F for the next two years. A year before the eruption, a 7.8magnitude earthquake struck about 60 miles northeast of Pinatubo, causing landslides and an increase in steam emissions from one of the volcano's geothermal areas, ultimately setting the stage for the 1991 explosion. While the eruption resulted in more than 700 deaths (mostly from collapsed structures due to ash accumulation the roofs), many scientists predicted the explosion, thus saving the lives of an estimated 5,000. Still, the eruption produced one of the most dramatic environmental scenes ever witnessed. With ash that rose 22 miles into the sky, it is considered the second largest volcanic eruption of the 20th century. Full documentary of the eruption of Pinatubo 1991 • • • • • Mount St. Helens was getting ready to burst for nearly two months before it exploded, not to mention the more than 120 years it lay dormant. While the eruption was anticipated, the manner in which it occurred was completely unprecedented. At 8:32 a.m. on May 18, 1980, a 5.1-magnitude earthquake triggered a sideways blast out of a dome on the side of the eruption. Scientists were caught of guard and were actually taking readings on the volcano when it erupted. It generated a pyroclastic flow of at least 300 m.p.h. that incinerated over 250miles of forest. About an hour later, the volcano created a massive lahar that buried towns and was moving as fast as 90mph. At the same time, a mushroom-shaped plume of ash shot 16 miles into the air, eventually covering three states. Complete darkness blanketed Spokane, Wash., a city about 250 miles northeast of the volcano. When the ash came down it fell in the form of black rain that literally coated the residents of Washington, Idaho and parts of Montana with a fine gray powder. Fifty-seven people and thousands of animals were killed, and some 200 square miles of trees were obliterated. Video of the eruption of Mt. Saint Helens • • • • • The Volcanic Explosivity Index goes up to 8. On that scale, the 1815 eruption of Mount Tambora rates a very destructive 7. The explosion took place on the island of Sumbawa (then in the Dutch East Indies, now in Indonesia) and plunged the region into darkness, but its effects were anything but isolated. Tens of thousands of people were killed by the massive pyroclastic flow, subsequent tsunamis and later by the ensuing starvation and disease. The largest volcanic eruption in recorded history changed the world's climate so much (even crops in Europe and North America failed) that 1816 became known as "the year without a summer.“ Tambora itself shrank several thousand feet and traded its peak for a massive crater at its summit. • • • Nov. 13, 1985, a relatively small explosion unleashed floods that swept away 1,500 people on one side of the mountain. On the other side was the town of Armero, the site of the worst destruction. 25-m.p.h. lahars obliterated the town and blanketed it in gray muck. When the landslides subsided, 23,000 people had died and damage was estimated at $1 billion — one-fifth of Colombia's GNP at the time. The eruption was small, in volcanic terms, that is, producing only about 3% of the ash ejected by Mount St. Helens in 1980. Instead, it was the lahars that made Colombia's 1985 Nevado del Ruiz explosion the second deadliest in the 20th century and the fourth deadliest in recorded history. The volcano has been blowing its top since the Pleistocene era and has erupted three times in modern history, including in 1595 and 1845. • • • • • The Toba eruption occur 75,000 years ago in India. This super volcano caused for a dramatic loss of human and animal. New research is showing the eruption may have been massive enough to spark an Ice Age, reducing global temperature 3-3.5degree, causing for even more loss of life. According to the Toba catastrophe theory, a massive volcanic eruption changed the course of human history by severely reducing the human population. This may have occurred when around 70–75,000 years ago the Toba caldera in Indonesia underwent a category 8 or "mega-colossal" eruption on the Volcanic Explosivity Index. This massive environmental change is believed to have created population bottlenecks in the various species that existed at the time. This in turn accelerated differentiation of the isolated human populations, eventually leading to the extinction of all the other human species except for the branch that became modern humans.