What would happen if Mount Vesuvius erupted today?

By: Cristen Conger  | 

Naples, Italy at the base of Mount Vesuvius.
Naples, Italy at the base of Mount Vesuvius.
Photodisc/Getty Images

When it comes to Italy's Mount Vesuvius, ­it isn't a question of if it erupts but when. Ge­ologists and volcanologists who study the volcano readily concede that Mount Vesuvius is overdue for an explosion [source: Fraser]. For that reason, the Vesuvius Observatory monitors seismic activity, gas emissions and other indicators 24 hours a day to know at the earliest point when it may blow.

The infamous volcano is best known for its nearly instantan­eous decimation of neighboring towns Pompeii and Herculaneum in A.D. 79. Considered one of the world's most dangerous, it is also the only active volcano on Europe's mainland. Nevertheless, 600,000 people live in the 18 towns at its base that comprise the "red zone."

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The red zone denotes the populated area that would bear the brunt of an ­eruption. Directly in the line of fire, the 9-mile (12-kilometer) radius of people stand little chance of survival when Vesuvius explodes again.

­Because of the imminent -- and unpredictable -- threat, the Italian government has devised an evacuation plan to clear out the red zone 72 hours ahead of an impending eruption. Beginning in 2004, the government also set up a program to pay people $46,000 (30,000E) to relocate outside of the zone -- though it has had relatively few takers. Experts warn that emergency plans should also include nearby Naples since an explosion could send dangerous burning ash and pumice as far as 12 miles (20 kilometers) [source: Fraser].

The last time Vesuvius activated was in 1944, causing minor damage and killing 26 people. New research has shown that the mountain probably will not act as kindly next time. For starters, Mount Vesuvius sits on top of a layer of magma deep in the earth that measures 154 square miles (400 square kilometers) [source: Noble]. That's a lot of magma -- Kilaeua Volcano is probably the most active volcano in the world, with 34 eruptions since 1952 [source: U.S. Geological Survey], but compared to Vesuvius, which has erupted around 30 times since 79 A.D. [source: Than], its magma supply is much smaller. Topping it off, scientists expect that the next eruption will be an incredibly forceful explosion, termed plinean, marked by flying rock and ash at speeds of up to almost 100 miles per hour (160 kph).

To summarize, if Mount Vesuvius erupts today, it wouldn't be a pretty picture. Given its potential, Vesuvius could endanger more than 3 million people and wipe out the city of Naples [source: Than].

Next, we'll learn what happened to Pompeii and Herculaneum that gave Vesuvius its notable reputation.

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Mount Vesuvius History: Pompeii and Herculaneum

An artistic rendering of Herculaneum before the A.D. 79 eruption of Mount Vesuvius.
An artistic rendering of Herculaneum before the A.D. 79 eruption of Mount Vesuvius.
Louis S. Glanzman/National Geographic/Getty Images

At 1 p.m. on August 24, A.D. 79, it began. Nineteen hours later, the two wealthy Roman cities of Pompeii and Herculaneum were almost erased from history. Signs of the incoming blast included a minor earthquake and underground water sources running out a few days prior [source: Stewart]. A plume of smoke rocketed 20 miles (32 kilometers) into the air from Vesuvius' opening, spewing forth its blisteringly hot contents.

The only eyewitness to account the eruption, Pliny the Younger, compared the smoke shooting up from Mount Vesuvius to a pine tree. Soon, the city was engulfed in smoke and noxious gasses from the mountain. Although most people escaped Pompeii, at least 2,000 who stayed behind were crushed or buried alive in the ash and rock that rained from the sky that day.

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On the other side of the mountain at the Bay of Naples, the seismic storm travelled to Herculaneum. In addition to clouds of ash and rock came a heat wave of almost 900 degrees Fahrenheit (482 degrees Celsius) [source: Lorenzi]. Many were able to escape the wrath of the volcano, but 80 bodies were found -- seemingly frozen in time -- killed instantly by extreme thermal shock.

­The A.D. 79 eruption buried Herculaneum in 75 feet (22 meters) of ash, while Pompeii remained under about 9 feet (2.7 meters). Since the area surrounding Mount Vesuvius was uninhabitable for centuries following the explosion, the cities eventually drifted from history, until 1748. Because of the fine dust and the speed at which it fell, Pompeii in particular was for the most part preserved intact. Architectural elements, artifacts and the hundreds of bodies stood unchanged until their excavation.

What archeologists didn't know until more recently was that the famous eruption was not the first or the largest from Mount Vesuvius. About 3,780 years ago, it burst open with more power, converting thousands of miles of landscape into desert for more than 200 years [source: Than]. Referred to as the Avellino eruption, it evidently caught thousands of inhabitants by surprise as well -- archeologists discovered deeply embedded footprints in the surrounding area.

A 1631 eruption killed 4,000 people and destroyed six villages [source: Woods]. In modern times, only one minor eruption occurred in 1944, resulting in 26 fatalities. Although geologists today can predict the severity of the next eruption, they cannot pinpoint a date, making Mount Vesuvius a ticking time bomb.

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Originally Published: May 12, 2008

Mount Vesuvius FAQ

Is Mount Vesuvius still active?
The last time Mount Vesuvius erupted was in March 1994. At present, it is the only volcano in the European mainland, on the west Italian coast, that is still active.
How many people died in Pompeii?
In 79 AD, Mount Vesuvius had a catastrophic eruption that destroyed and buried the Roman settlements of Pompeii, Oplontis, Herculaneum and Stabiae. The death toll is estimated to be close to 16,000 people total and 2,000 Pompeiians.
What if Mount Vesuvius erupts today?
When Mount Vesuvius eventually erupts again, 18 towns that are home to nearly 600,000 people could be wiped out in an area known as the “red zone”. Burning ash and pumice put other people up to 12 miles away at risk as well. Because of the risk, the Italian government has 24-hour monitoring of the volcano and a evacuation plan to clear the red zone area three days before an eruption.
How old is Mount Vesuvius?
Though its exact age is unknown, Mount Vesuvius is somewhere around 200,000 years old. Before eradicating Pompeii and its nearby cities in 79 AD, it remained dormant for many centuries.
How tall is Mount Vesuvius?
Mount Vesuvius is 1,281 meters tall from base to summit.

Lots More Information

Related HowStuffWorks Articles

More Great Links

  • Bruni, Frank. "Who's Afraid of Vesuvius?" The New York Times. Aug. 26, 2003. (May 1, 2008)http://query.nytimes.com/gst/fullpage.html?res=950DE7D71239F935A1575BC0A9659C8B63
  • Fraser, Christian. "Vesuvius escape plan 'insufficient'." BBC News. Jan. 10, 2007. (May 1, 2008)http://news.bbc.co.uk/2/hi/europe/6247573.stm
  • Graham, Sarah. "Study Shows Massive Magma Chamber Lies Beneath Vesuvius." Scientific American. Nov. 19, 2001. (May 1, 2008)http://www.sciam.com/article.cfm?id=study-shows-massive-magma
  • Hale, Ellen. "Italians Trying to Prevent a Modern Pompeii." USA Today. Oct. 21, 2003. (May 1, 2008)http://www.usatoday.com/news/world/2003-10-20-vesuvius-usat_x.htm
  • Lorenzi, Rossella. "Pompeii: The Last Day." Discovery Channel. (May 1, 2008)http://dsc.discovery.com/convergence/pompeii/history/history-07.html
  • Lorenzi, Rossella. "Vesuvius Residents Paid to Move Away. Discovery Channel News. Dec. 6, 2004. (May 1, 2008)http://dsc.discovery.com/news/briefs/20041206/vesuvius.html
  • Nordland, Rod. "The Sleeping Monster." Newsweek. Sept. 28, 1998. (May 1, 2008)
  • Stewart, Doug. "Resurrecting Pompeii." Smithsonian. February 2006. (May 1, 2008)http://www.smithsonianmag.com/history-archaeology/pompeii.html
  • Than, Ker. "Vesuvius Could Destroy Naples, History Suggests." LiveScience. March 6, 2006. (May 1, 2008)http://www.livescience.com/environment/060306_ancient_vesuvius.html
  • Woods, Michael and Woods, Mary B. "Volcanoes." Lerner Publications. 2006. (May 6, 2008)http://books.google.com/books?id=k_mCKWwA43YC

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