MT. VESUVIUS ERUPTS
The power of a volcano and the uncertainty of when one will
erupt has long been a source of interest for many.
Fortunately, scientists are getting better at reading the signs of
when a volcano may be due to erupt.
This week, nearly 2 000 years ago, Mt. Vesuvius in Italy
exploded in a spectacular and devastating way.
Before the AD 79 eruption, there were signs that Vesuvius was
beginning to stir. Earthquakes had struck the area and
underground springs had dried up. Unfortunately, people
didn’t know how to read or understand the signs back then.
Therefore, when the eruption of Vesuvius started on August 24
AD 79, the locals were totally unprepared.
It was a Plinian eruption that struck that day, the most
dangerous type. It involved super-heated gas, magma and
ash forming a giant towering column up into the sky. The
magma cooled and fell to the earth as pumice. A reservoir of
boiling magma, three kilometres wide formed within Vesuvius,
trapped inside by a plug of old magma. A chemical reaction
involving water and gases finally shattered the lava plug and
Vesuvius roared back to life.
Mixed in with the pumice stones were lithics, cold dense rocks
torn from inside the volcano and carried up into the
atmosphere, falling back to earth as deadly missiles at speeds
of 180 kilometres per hour. At the peak of the eruption, a
staggering 100,000 tons of magma, ash and gas were
released every second, travelling at the speed of a jet to
reach 33 km in height; 3 and a half times the height of Everest!
A dense black cloud of ash blocked the light and crowds of
screaming people fled in terror. We know this thanks to Pliny
the Younger, a scholar who kept a written record of what
happened at the time. The eruption lasted for more than 24
hours. Those who fled at once had a chance of survival
because the ash and rock that rained down for several hours
was not necessarily lethal. It is clear though that many thought
their best chance was to take shelter and wait for it to pass.
24 AUGUST AD 79
Unfortunately, this wasn’t the best option. At around
midnight the first avalanche of hot ash, pumice, rock and
volcanic gas rushed down the side of the volcano at 100
km per hour. Some people headed towards the beach,
thinking they could escape by sea, but they found the
waves too high and dangerous.
Hundreds of people who had stayed behind sheltering
and protecting themselves and their valuables, died from
the intense heat of the first surge that reached the city.
When the waves of ash, rock and gas reached Pompeii,
the poisonous fumes suffocated the people and livestock
that remained. The waves smashed the upper floors of
houses, and left the dead covered in blankets of gas,
ash and rock. The impact of the eruption even caused
the Sarno River to change course and ash fall was
traced as far away as Africa.
The cities of Pompeii and Herculaneum were buried
under tons of volcanic ash. What is truly amazing is that
these lost cities were perfectly preserved by the ash.
For many centuries Pompeii and Herculaneum remained
forgotten. No traces were discovered until 1713, when
some labourers came upon the remains of Herculaneum
over 7 metres underground. Little attention was paid to
the discovery then but in 1748 a peasant stumbled on
some ancient works of art and the remains of Pompeii
were found.
This discovery led to further research and excavation.
Under the layers of rock and ash, the city remained
intact. The buildings and the contents inside the houses
and shops provided a fascinating picture of "daily life”.
Some spaces in the ash layer contained human remains
left by decomposed bodies. Plaster was injected into the
spaces to recreate the forms of Vesuvius's victims. The
body casts of these victims as well as many other
fascinating artifacts are now part of an exhibition that
tours the world.
MT VESUVIUS ERUPTS
24 AUGUST AD 79
Discussion Questions
Factual
1.
Where is Mt. Vesuvius?
2.
What were two of the signs that Mt. Vesuvius was due to erupt?
3.
What type of eruption was it?
4.
What are lithics?
5.
Was the best action to take; a) flee at once or b) take shelter?
6.
What were two of the major causes of death from the volcanic eruption?
7.
How is it that we can see perfectly preserved artifacts from the eruption today?
Challenge
8.
Imagine you were a local living in Pompeii on 24 August, AD 79. Write one paragraph
to describe what you saw and how you felt when Mt. Vesuvius started to erupt.
Did you think it would die down and was nothing to worry about, or did you panic and
expect the worst? Did you flee or stay? How did those around you react?
Use lots of descriptive language!