Earlham College - Geology 211

Mount Vesuvius, in the times of the Greeks and Romans, was sacred to Hercules. Hercules is a well known hero and "demigod", so called because he is half man, half god-- son of Zeus, the "boss" of all the gods by a human woman, Alcmene. Zeus was also known as "Ves" and Hercules was also called son of Ves, or "Vesouuios". The town directly at the foot of Mount Vesuvius was named directly after Hercules: Herculaneum. The volcano was also named after Hercules, but using a corrupted form of the name "Vesouuios" instead of Hercules.

NPR: Keeping an Eye on Mount Vesuvius
This is just cool-- listen to an interview by Scott Simon with Haraldur
Sigurdsson, a volcano expert and professor of oecanography at University
of Rhode Island.

http://www.npr.org/templates/story/story.php?storyId=4123769&sourceCode=RSS

Nice image of Mount Vesuvius on the NASA news site.

http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=4541

Locations of volcanoes in Europe and part of Asia: small red triangles are volcanoes that are still active but haven't erupted for a few hundred years, while the large red triangles are volcanoes that have erupted within the last hundred years.

Smithsonian Natural Museum of Natural History, http://www.volcano.si.edu/world/volcano.cfm?vnum=0101-02=

All photo and pictures used courtesy of the Smithsonian website, which you should visit!

http://www.volcano.si.edu/index.cfm

Mount Vesuvius

Photo by Dan Dzurisin, 1983 (U.S. Geological Survey), Smithsonian Natural Museum of Natural History, http://www.volcano.si.edu/world/volcano.cfm?vnum=0101 02=&VErupt=Y&VSources=Y&VRep=Y&VWeekly=N&volpage=photo

Mount Vesuvius is famous for the eruption in 79 AD that buried Pompeii and Herculaneum. This eruption has been made famous because of the way the towns were preserved, especially Pompeii, where archeologists have even been able to make molds of the people who were killed by the eruption. There is also a first hand account of this eruption by Pliny the Younger. This web page will focus more on the hazards of Mount Vesuvius today.

Facts About Vesuvius:

Has an elevation of 4,200 feet, or 1,281 miles
It is a rhyolitic volcano- its eruptions are violent and explosive, either lava or a speeding cloud of hot ash called pyroclastic flow erupt from the volcano. With pyroclastic flow comes debris called tephra that can range from ash and cinders to "bombs" the size of a football that can kill on impact
It is a composite volcano- it is composed of alternating layers of ash and lava. It is also a somma volcano. It has a caldera- the mouth had been previously blown off and there is now a deep crater with a new mouth inside of it, and there is now a new mouth inside the caldera.
It sits above the subduction zone between the African and Eurasian plates. The African plate is subducting (going underneath) the Eurasian plate.

How Volcanoes are Created:

Artist Jose F. Vigil, Simkin and others, 1994, Smithsonian Natural Museum of Natural History, http://www.volcano.si.edu/world/volcanocriteria.cfm#VolcanoImages

Most volcanoes are created by subduction. As is shown by the picture above, subduction occurs when tectonic plates collide. When one plate is heavier than the other, it will subduct, or go underneath, the lighter plate. When this happens, the plate that subducts eventually becomes molten and becomes a part of the core of the earth. However, right over the area where the plate actually subducts, it is common for some magma to escape and creep up towards the surface. This will leak out or explode out of the earth, gradually forming what we think of as a volcano. This is how Mount Vesuvius was created.

Some volcanoes are created by "hot spots", where the crust is weak and allows magma to flow upwards and get through the crust. (Again, shown in the picture above.) These hot spots do not coincide with subduction areas and are usually towards the center of a plate, where the crust is spread thin because it is being pulled apart. The Hawaiian islands were created by a hot spot.

Mount Vesuvius today:

Mount Vesuvius last erupted in 1944. Today it is a background to the city of Naples. Its lower slopes are incredibly fertile and are covered 18 small towns (number from 2003) and numerous vineyards, which produce the famous Lachryma Christi wine. It is circled by a railroad track and there is a chairlift that reaches almost to the rim of the crater. There is a seismological observatory on the mountain, but Mount Vesuvius still is not a safe place to live or work.

Impacts:

Scientists have recently discovered that there are two magma reservoirs below Mount Vesuvius, a large deep reservoir and small shallow reservoir. This was discovered when scientists created seismic waves and were able to measure how the waves flowed through the ground. Waves flow differently through liquid than through solid, and certain kinds of seismic waves will not flow through liquid at all. However, this discovery still does not allow scientists to predict the date of the next possible explosion.
Today there are approximately one to two million people who live and work in the immediate area around the volcano and who would be the most affected by it if it erupted again.
In the first 15 minutes of a medium to large eruption, a 4 mile radius around the volcano would most likely be destroyed.
Scientists believe that the next eruption will most likely be an explosive eruption, similiar to the eruption that completely covered and destroyed Pompeii and Herculaneum.
Vesuvius is a somma volcano- its original mouth was destroyed and it has another one inside the first. The caldera that was created when the original mouth was blown off is still mostly intact and almost completely circles the new mouth. These actually have two seperate names. The caldera is reffered to as Mounte Somma, and the actual mouth of the volcano is Mount Vesuvius.
Vesuvius is still regarded as an active volcano, although its activity has been limited to letting steam from small vents in the bottom of the crater.
Eruptions from Vesuvius are usually explosive, and have occasionally been so large that ashes from the eruption blanketed most of southern Europe- in 472 and 1631, ashes fell on Istanbul from Vesuvius. Istanbul is fully 1,000 miles away.
The record of volcanic activity for Vesuvius suggests that the longer it takes for the next eruption to occur, the more dangerous and explosive the eruption will be.

Author: Amelia Catalano kisses
Creation/revision date: April 11, 2005

Link to other Student Webpages for 2005 Earlham Physical Geology

This website was prepared as an assignment for Geosciences 211 (Physical Geology) taught in the spring of 2004 at Earlham College, Richmond, Indiana.

Earlham College· Geosciences Department · Earlham Geosciences 211: Physical Geology