The Decade Volcanoes – Mount Etna

Mount Etna is an active stratovolcano on the Italian island of Sicily and, as one of the most active volcanoes on the planet, is no stranger to the public eye. The volcano has documented eruptions dating back to the 1500s with modern eruptions regularly being captured on camera. Broadly speaking, the volcano formed as a product of the subduction of the African Plate beneath the European Plate, a process that will eventually see the closure of the Mediterranean Sea.

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In 2009, the International Space Station flew over the Sarychev Volcano on the Kamchatka Peninsula just as it was erupting and punching a spectacular hole in the clouds. The photos and videos of it are some of the best we’ve ever seen of an erupting volcano from above. Take a look at the pyroclastic flows streaming down the sides of the peak as the station passes (shaking is the camera position adjusting as the ISS moves).

Was Pompeii The Worst Volcanic Disaster Ever?

This August 24th is the 1936th anniversary of the eruption of Mount Vesuvius and the destruction of the ancient Roman city of Pompeii. Rediscovered in 1748, the 3-square-km site has been undergoing an excavation since. As modern archeological and scientific techniques get more advanced, we are continuing to learn more and more about that infamous day. The eruption occurred around lunchtime on August 24, 79 CE. Eyewitness Pliny the Younger wrote, “a cloud of unusual size and appearance,” shot into the air from Vesuvius, reminding him of an umbrella pine tree. Vesuvius’ column reached 27 miles (43km) into the sky before branching out and raining ash and pumice stones on the 2,000 Pompeians who didn’t have time to flee the doomed city.

Surviving records indicate there were signs that something bad was coming. Fish were floating dead in the rivers, wells were drying up, and the vines on the slopes of the volcano inexplicably dried up. Plus, there were increasingly violent and regular earthquakes were hitting the region. Today we know that volcanoes swell slightly before they erupt, as the pressurized magma bulb rises through the earth. A volcanic mountain can leak noxious gases before it erupts, which might have contributed to the death of the plants and fish. After midnight on the following day, between three and six massive superheated pyroclastic surges (avalanches of high-speed rock, dust, and volcanic gas) buried the city in volcanic ash and dust. When volcanic ash gets wet, it hardens like cement, preserving anything trapped inside. Over time, the clothing and soft tissues of the Pompeians decayed. In 1777, excavators discovered an air pocket in the shape of a body, and almost 100 years later the director of excavations found a special mix of plaster of Paris which could be poured into these cavities to mold out a body, revealing in striking detail the last moments of these some of the 2,000 estimated people who died.


On August 24, AD 79, Mount Vesuvius, a stratovolcano, erupted. When Mount Vesuvius roared to life, the doomed residents of nearby Pompeii had no idea they were living in the shadow of a volcano. What happened?

  • At around noon on August 24, Vesuvius stirred. Ash and pumice began raining down on the streets of Pompeii.
  • Residents tried to flee, but escape was futile. The air was growing thick with ash, the sea too turbulent to navigate.
  • Those who remained perished as pyroclastic flows—avalanches of scorching ash and gas—enveloped the town. By dawn of the following day, Pompeii lay buried beneath ash and rock.

Vesuvius had erupted before. Just not within the memory of those going about their business in Pompeii’s bustling streets when the volcano awoke. Today, more than 3 million people live in Vesuvius’ shadow and could be at risk when Vesuvius springs to life again.

Learn more about the science behind the eruption of Mount Vesuvius.

Image: AMNH/K14221


Volcanic searchlight

Villarica (AKA Pucon) has been erupting for several months (see http://on.fb.me/1Mt9jky), and while the activity remains low key with seismic tremor, glowing craters and some lava fountaining, the smoking mountain is still producing some fantastic visual effects. Here a beam of red volcanic light is shining brightly up towards the clear winter stars over the Andes, that great chain of mountains born of the subduction of the Pacific oceanic plate under the South American continental one. The current alert level is only yellow, and we’ll keep you posted if things change. In the first photo our hime island universe’s two largest satellite galaxies, the large and small Magallanic clouds are clearly visible as the cloud like objects, one just to the right of the beam and one seemingly in it.


Image credit: Agencia Uno