Avi Ben Shitrit

Richard Stockton College of New Jersey

The Earth, Geology   

Mt Vesuvius

     The picture above shows a picture of Mt.Vesuvius, active, and the cities which surround the volcano which proved to be awfully destructive, wiping out Pompeii and Herculaneum in 79A.D.

The Two Cities

Pompeii

The name Pompeii originates from gens pompeiana, which translates into the people of Pompeii.  The city of Pompeii lies south of Mt. Vesuvius in the western part of Italy.  Pompeii initially developed as a  farming community which was found at the River Sarno before the sixth century BC. Resting between fertile grounds and the sea, Pompeii  traded its own wine, oils, and flour products. The inhabitants used the sea for fishing and the port for trading their agricultural and industrial products.  Pompeii was also exporting fragrances, cloths, sauces, and stones. Pompeii grew rapidly from a farming town to an industrial town.  Before long, Pompeii drew the attention of surrounding cities because it had the land and sea to its advantage.  In order to prevent future acts of jealousy against Pompeii from surrounding cities, Pompeii joined alliances which brought them down and led to their defeat in the Social War of 91-87 BC. by Roman general L.Cornelius Sulla, whos dictatorship was notorious for its cruelty and lack of legality.  

The architecture of this port city was unique in that it was 3km round in circumference.  The town square was centralized and the temples, theaters, and public baths surrounded it.

The inhabitants did not anticipate the  first major disaster, the earthquake of 62 AD.  Despite the destruction and rubble, the survivors were set out to rebuild  and expand.  Upon the completion of this construction, the eruption of 79AD struck.     

 Herculaneum

The town of Herculaneum is called the "town of Hercules" because the inhabitants think that Hercules may have stopped there on his way back from Spain.  This town consists of about 55 acres.  Geographically, it is located on the shore of the Bay of Naples and is slightly northwest of Pompeii.

The buildings and structures of Herculaneum used orderly rectangular blocks, made by the Greeks, which were similar to that of Naples and therefore it is believed that these cities were constructed by Greeks.  Pedestrians were protected, from the sun and rain when they were walking on sidewalks, by roofs or awnings, which were supported by wooden beams. The columns which covered the walkways were constructed to protect the townspeople from bad weather.  Another beneficial construction of this town was the drainage system which drained rainwater and wastewater out to sea. The towns  water supply flowed in through aqueducts from the mountains.

The people of Herculaneum enjoyed watching their sports in the palaestra which was the gymnasium. The sports events they had along with the feasts following the events were  paid for by the wealthy towns people.

Mt. Vesuvius

   Mt. Vesuvius is located in a subduction zone where the Earth's surface is being pushed below another section.  The sections which are talked about are called plates.  When two plates rub against one another, they will either cause an eruption or an earthquake.       This picture shows the plate boundaries.
  A volcano will begin to form when one of the earth's plates is subducted or shoved under another one of the earth's plates. The rocks of the plate beneath work their way into the earth and melt.  After they melt forming magma, the density of lava which is less than the surrounding rocks, forces the magma upwards through a weak point in the surface which will slowly  be used to form a volcano.    This picture shows the subduction zone.
Mt. Vesuvius has alternate layers of lava and ash which categorizes it as a composite volcano. Composite volcanoes produce two different types of eruptions: one which produces mostly ash and cinders and another which produces lava.    The light layers represent the lava and the dark layers represent the ash.

What will determine the type of eruption?

The type of eruption can be determined by the composition of the magma.  Basaltic magma will flow more easily because it is low in silica.  Rhyolitic magma wont flow as easily because the magma contains a higher content of silica which would make it sticky or gooey.  Another way to determine the type of eruption is by the water and gas content.  

Earlier signs which may have generated curiosity were: the wells and springs which mysteriously dried up; flock of birds that flew away; and animals were restless.  The reason the wells dried up was because the increasing heat and pressure that were building deep in the earth, and that animals are more sensitive than humans to changes in the atmosphere.  But the townspeople did not make the connection between these signs and the disastrous eruption which was to come.

When Vesuvius erupted on the afternoon of August 24, 79AD, the volcano blew out a cloud of coarse pumice out of its summit.  Once this cloud cooled, it collapsed, sending ash and hot gas racing down the slope, ripping the roofs off houses and overturning ships in the bay.

Although Pompeii lay five miles away, its disadvantage was the wind which was blowing in its direction when the eruption occurred.  Throughout the afternoon and evening of August 24th, ash and pumice rained on Pompeii, frightening and scaring away the inhabitants.  But it was not until early the next morning that the first flow of hot gas and dash surprised the town, killing 2000 people.  The fallen bodies of the Pompeiians were buried under twelve feet of ash and pumice.  When the dead bodies rotted, they left hollow places in the hardened volcanic rock.

Herculaneum, which was less than three miles from Vesuvius, was upwind of the volcano.  Most of the falling ash blew upwind and opposite of the volcano, leaving less than and inch of pumice over the town by the end of the day.  Instead, early the next morning. A violent surge of ash and hot gas poured over the town.  By the time the hot mud followed, everyone was dead.  Within a few hours Herculaneum was completely buried under sixty-five feet of hot volcanic matter, which, when it cooled, covered the town like a cement shield.

Sealed by volcanic ash and rock, the buried buildings have been protected from the wind and rain that would have worn down the columns and statues over the centuries.  Unlike other ancient towns, the roads and buildings have not been repaired, or torn down and replaced by something more modern.  Now, Herculaneum and Pompeii look the way they did so many years ago.  The roofs of the houses may be gone, the mosaic floors cracked and the walls paintings faded.  But we can still walk down the stones that the ancient Romans walked on.