entry Apr
2010, update Nov 2018
Big
Archie & Living on the Edge
The
Archiflegrean Caldera is the area
bounded
by the red lines with wedges. The area
shown
in the map is about 30 km/20 miles
across.
I
have always known that the area is
volcanically a bit “iffy.” After all, from my
balcony (about where the word "Chiaia" (lower right)
is, above "Bay of Naples" in this image) I can see
Mt. Vesuvius way over to the east. It (Vesuvius, not
my balcony), has been quiet, lo, these last 66
years. (And that’s just one 6 short of a hell of a
volcano!) But that’s only the tip of the volcano.
Vesuvius is a child (less than 20,000 years old)
compared to the roaring land-forming engines that
earlier produced almost everything else in this
image: the Fuorigrotta Plain and everything to the
west of the Posillipo hill until you get to Capo
Miseno, Monte di Procida, and Cuma
at the western end of the Gulf of Naples. There are
still remnants (Monte di Procida is one) of the
cataclysmic caldera collapse of the so-called Archiflegrean
volcano or Caldera (also known as the
Campanian Ignimbrite Eruption); it was a
super-volcano that exploded
40,000 years ago, tearing the roof off itself, settling back to
sea-level and below. Bits of the ancient
volcano rim of Big Archie (my term of endearment)
are very visible on the surface. As you go through
the area, you go through Agnano, the Astroni, and other places,
all parts of the Campi Flegrei,
or Flegrean Fields. Flegrean means "fiery." They are
remnant and extinct (probably) volcanoes from
secondary eruptions from the so-called Second
Flegrean Period (c. 20,000 ago). That second,
smaller area is simply named the Flegrean Volcano
(bounded by the black lines with wedges, centered on
the town of Pozzuoli). One area, the Solfatara, is still
wheezing if not active, but it could erupt, they
say. The Flegrean Volcano produced the Posillipo
hill, the slopes of which attracted the Greeks, then
Romans and now a bunch of other optimists who never
studied geology.
(See this page
for a photograph shot from the NE rim — the
Camaldoli convent across the entire Campi Flegrei to
the remnant SW rim above Baia.)
update added Nov. 2018
- See this link for
the latest studies on the ominous "bulge beneath the
bay."
A bit to
the east, I (and thousands of others —photo,
right) live on the northern slope of another
earth-engine called the Chiaia volcano (again, right
where that word, "Chiaia" is in the above image). It
had not occurred to me before, but as I look from my
balcony to the south, the postcard below me is a
vast amphitheater, a semi-circle with the Egg Castle
on the left and Mergellina on the right with that
western end of the amphitheater extending out to a
point called Cape Posillipo. The stage below me
(photo, below) is at sea-level and Capri is dead
ahead, a backdrop, 25 miles away. From the slopes of
the ancient Chiaia crater, we all have great seats
for whatever is to come. That original explosion was
a piker compared to Big Archie of some eons earlier,
but it did form what is now the Chiaia section of
Naples and most of the Vomero hill above it.
From
the sea, the Vomero hill above me seems to run
over to the west and form a single long ridge with
the Posillipo hill. That is deceptive. They do run
together, after a fashion, but only because the
Chiaia volcano came first, and then the
smaller-than-Archie Flegrean volcano to the west
blew and spat out the Posillipo hill partially on
top of it.
All of this volcanic activity has made the
area rich in yellow tuff, a sandstone, the
ubiquitous building material in Naples. I am
currently in the midst of translating a book about the subsoil of Naples.
Co-translator, Larry Ray, writes this in his
presentation of the translation for the Napoli
Underground website:
...the tuff sandstone
strata are honeycombed with hundreds and hundreds
of gigantic manmade cavities where the durable
sandstone had been quarried and brought to the
surface to build palaces, villas and other
buildings over the centuries. Additionally other
voids included railroad tunnels, ancient Greek and
Roman aqueducts and water reservoirs, long tunnels
from the city's pneumatic mail and message network
from the early 1900's, as well as elaborate
network of ancient as well as operating sewer
lines, gas lines and other similar cavities...
All of that
is a cause for concern in construction around here.
There is not an area in the city that is not
undermined in some fashion or other. And maybe not
even a building. We get earth slides and cave-ins
frequently. I have learned to be as fatalistic about
that as I am about volcanoes. My Chiaia explosion
must have come from right where that rich guy’s
yacht is anchored. If Chiaia goes “ka-blooey” (to
use the geological term) again, he’s a goner. But,
then, so am I.
added May 12, 2019 —
an interesting update, to say the least, is here.
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