John Pazmino
2005 June 24
Among the final free public lectures of the 2004-2005 season at
Science, Industry, and Business Library was 'Future eruptions of
Vesuvius' This was presented on Wednesday 22 June 2005 by Dr Flavio
Dobran of Hofstra University. He is also active in 'Vesuvius 2000', an
international effort to develop and implement a response plan for a
reasonably foreseeable future eruption of this volcano.
Vesuvius (it's just that, not 'Mount Vesuvius') is unusual for
being a live volcano close to an urban region with a history of
catastrophic blowups. It sits about 12 kilometers from central Naples,
being a prominent feature of that town's landscape. Around the volcano
is a dense suburban zone.
The volcano is tiny compared to most other active ones, but it
packs a wallop when it explodes. The small size allows population
close in, within 6 kilometers!, before the slope is too steep to build
on and travel around on.
By the tens of our era, the Romans built up the region around
Vesuvius for its fertile land, made so by the blanket of volcanic ash
from prior, unrecorded, eruptions. Pompeii and Herculaneum were
considerable towns, like those of mid America, with myriads of
residents, thriving economy, and active culture. They sat 7 kilometers
from the crater. A larger town, Neopolis, taken over from a Greek
settlement, was about 12 kilometers away. This is present day Napoli
in Italian or Naples in English.
Today, about 600,000 souls reside within 7 kilometers of the peak,
some 3,000,000 within 50. The latter includes all of Naples and its
surrounds. Altho everyone knows about the volcano, they seem blase'
about living so close to it.
To visualize the situation of Vesuvius, let central Naples be at
Bowling Green, Manhattan. The crater would sit near Randolph Sq (116th
St & St Nicholas Av)! The proximity of built up land would reach up to
the American Museum of Natural History and the Metropolitan Museum of
Art!! It would also rank among the tallest peaks east of the
Mississippi, some four times the height of the late World Trade
The 79AD eruption
The first records and most famous eruption is that of 79AD. For an
early geological event, it was amazingly well documented in an
objective fashion. This could be one of the first major catastrophes
to be described without the 'biblical' narration of earlier eras.
Perhaps this was due to the general maturity and cultural level of the
Roman people?
The dense population, even back then, produced accounts from
various viewpoints and distances, assembling for us today a
comprehensive picture of the eruption. Some of the writings of that
event are still used today as reading assignment in lain classes!
The area around Vesuvius was already known for its tremors. The
entire Mediterranean Sea experiences earthquakes routinely so there
was nothing abnormal about those around Vesuvius. Apparently there was
an extra earth movement on 24 August 79ADD that alerted the populance
to a potential major earthquake.
They got a lot more. The volcano exploded suddenly. Within hours
it wiped out myriads of people for a dozen kilometer around. Pompeii
and Herculaneum were effaced. Excavations since then reveal the
magnitude of the tragedy, some of which is open for tourists to
The 1631 eruption
Since 79AD the volcano went to sleep. People moved back into the
hazard zone, Naples grew into a major city-state by the Middle Ages.
Much of the history was lost in the Dark Ages.
On 16 December 1631 Vesuvius blew up again. This eruption was also
incredibly well chronicled, this time with paintings and drawings and
maps. The destruction leveled many new towns and erased thousands of
lifes. One larger fatally hit town was San Sebastiano.
There is some debate for the faithfulness of the depictions for
this event. Some scientists argue that the spectacle was exaggerated.
Others claim there was no need for extra hype. The eruption was one
hell of a show on its own. Regardless, the accounts of the 79 and 1631
explosions are used to calibrate modern computer simulations of
Vesuvius to an reasonable degree of confidence.
Some astronomy
Dr Dobran didn't mention this, but I saw the connexion right away.
The craters on the Moon were only just appreciated with the newly
invented telescope. They resembled volcano craters on Earth, there
being many known from old volcanos. In fact, there are a couple near
Vesuvius! Surely, with the spectacle of the eruption before them, it
took little mental exercise for people to conclude that the lunar
craters were the result of volcanos.
It would be over three centuries before any other cause for the
lunar craters was seriously taken up! Not until the 1930s was the
alternative, now probably the principal cause, studied: meteor and
asteroid collision.
Mt St Helens
The give and take of the audience compared Vesuvius with Mt St
Helens. The capital difference is that Mt St Helens is in a wilderness
region, well away from population centers. Yet, that peak is a skyline
feature of both Portland, Oregon, and Seattle, Washington. These are
large towns on the Pacific coast. While they were never in direct
danger, the explosion was heard by them and caused mass anxiety.
An other difference is that Vesuvius blew off verticly, like a
cartoon volcano. Mt St Helens blasted out from one side. By the way,
Mt St Helens is right now under a new pressuring, with venting of
steam and ash. The show is a big tourist attraction from a safe
distance away.
The next eruption
Dr Dobran explained some simulations and studies to foretell when
the next eruption may come, and its severity and extent. There really
is no good way to reliably predict a volcano event. All that he and
other geologists, can say is that Vesuvius WILL blow and cause
incomprehensible devastation around it. Will this happen in the next
couple decades? Later in this century? A couple centuries from now?
With no credible predictive process in hand, it is hardly wise to
issue alerts for evacuation or other defensive action. The squander of
financial and human resources and the disruption of daily routine from
a false alarm will for very many years kill the credibility of any
future, perhaps real, alarm.
And that constitutes the situation at Vesuvius. The bulk o
Dobran's talk dwelled on the absolute need to provide for the eventual
blowup of Vesuvius. There is nothing in place now, but some soft
passive discussions and tuition in schools.
Vesuvius 2000
From time to time over the decades Italy studied ways to protect
the inhabitants from a future Vesuvius eruption. For the most part,
according to Dobran, they were inept and infeasible. Most of them were
based on the presumption of orderly civil rule and integrity of escape
routes. Neither can be counted on in a sudden catastrophe.
For example, people could be assigned to take certain trains out
of the danger zone. Lava or earthquake could easily break up rail
lines. Rail crew could be killed or injured. Signals and power could
be cut. And so on.
The plans allowed that once the people were moved out of the
danger zone, all was well and done. Now you have several hundred
thousand homeless folk slapped onto an already populated region with
no subsistence and no obvious return to their land.
An other study called for gigantic civil works for penning or
diverting lava flows away from the towns. Yes, believe it or not, such
a project can be built, forgetting the expense and time. After the
lava is contained, it will harden in place, removing the dikes and
canals from possible later use. More immediately, the structures will
for decades or centuries interfere with human activity near them.
One bizarre schemes would purposefully make the danger zone unfit
for habitation. No kidding. The state would withdraw social and civic
functions, let services and facilities decay, abstain from keeping
order and peace. Within a decade the people will on their own move
out. Now you got a depopulated area around the volcano, to be fenced
off, guarded, and patrolled.
Vesuvius 2000 seeks to impress on Italy and other countries to
take a more considered look at the Vesuvius situation. So far, nothing
seems even remotely credible. It is plain impossible to move a million
people on sudden notice to beyond 50 kilometers from Vesuvius within a
few hours. That's the timescale of a potential warning of an eruption.
Other evacuations
I compared the case of Vesuvius with other evacuations. One that
has intriguing parallels was the escape plan for a radiation discharge
at Shoreham nuclear station. This, now dormant and never actually in
operation, sits on the north shore of Long Island about as far out as
Riverhead. The debates and arguments about shifting the inhabitants
away from the station were, to be kind, ffulgescent.
The warning, unlike for a volcano, would be pretty certain and
timely. The problem was the utter lack of means to move the people
away and the total disregard for their subsistence at their relocation
sites. In the end, the futility of an escape plan prevented the
station from ever getting into gear. It stands empty, cold, dark.
Similar parallels can be made with hurricanes on the Florida Keys,
earthquakes in Southern California, and, oh yes, the collision of a
asteroid or comet.
The actual danger
Most people think of a volcano for its flood of lava. Lava is
melted rock, heated inside the Earth and poured out from the crater.
This stuff definitely is dangerous for its heat and mass. However,
lava tends to move slow enough to anticipate its path. You have time
to evade or escape from it. Of course, the flow causes essentially
unrecoverable damage by engulfing all in its path and then freezing into
solid rock.
The greater hazard is the blast of superheated and poisonous gas
that shoots down the volcano slopes. Traveling at hundreds of
kilometers per hour and heated to around 1,000 degrees Celsius, this
air instantly suffocates and internally sears anyone in its path. You
can not see it coming nor have time to get away. Almost all the deaths
of Vesuvius's previous blowups were from this gas.
The downpour of ash causes few additional deaths, like burying
injured people who can not climb out. It will impede rescue and
recovery and will cause peripheral hazards. It clogs ventilation and
heating systems, silts up harbors and canals, induces lung and throat
ailments, grinds up machines and motors, contaminates water and fuel
supplies. It caves in roofs, blankets roads, airports, rails, smothers
farms, chokes animals.
Cost-benefit analysis--------------
The Vesuvius case spotlights the problem faced where some disaster
could inflict substantial human damage, yet people willingly and
cheerfully live inside the danger zone. Why?
There seems to be a balance between the perceived risk and prior
experience. People don't mind frequent low-level disasters, like storm
flooding. They don't mind cataclysms which occur once in millennia,
like a tsunami or, ahem, volcano.
Some where in between there may be a conscious ration for so-so
hazard and so-so frequency. No one knows what this balance is or have
to tilt it toward the safe side of action.
The session winded down with crosstalk about disaster response,
hazard determination, mass psychology, government competence, and
other related subjects.