WARNING:
Access to the summit area is EXTREMELY
DANGEROUS. Violent eruptive episodes are occurring
about twice per day at the Southeast Crater, and heavy showers
of tephra (including clasts tens of centimeters in diameter)
may occur up to several kilometers away. It
is absolutely not safe to stay in the area of the Torre del
Filosofo mountain hut. Besides this, weather conditions
are often unstable. The winter brings frequent snow storms and
clouds, and one gets easily lost due to the lack of points of
reference once there is a thick snow cover. Excursions should
be made only with the mountain guides who can be contacted at
the cable car (near the Rifugio Sapienza) on the southern side
of Etna, or at the hotel "Le Betulle" at Piano Provenzana,
on the northern side.
|
26
February 2000 update.
Since Sunday 20 February, there has been only one eruptive episode
at the SE Crater, early on 23 February. This event lasted more than
one hour and consisted mostly of vigorous Strombolian activity, culminating
in a very brief phase of lava fountaining. Since then the crater has
remained quiet, with only light fuming occurring from its summit area,
and the fractures on its northern and southern flanks.
During a summit visit on 25 February, Behncke, Carniel and Fulle noted
eruptive activity only at the Bocca Nuova, while the SE Crater remained
completely quiet. The Bocca Nuova produced discrete explosions at
intervals of a few minutes, many of which produced beautiful "smoke"
rings.
22
February 2000 update.
More eruptive paroxysms have occurred at the Southeast Crater, but
it is not clear precisely when, because bad weather is frequently
hampering visual observations. Until Sunday 20 February, the number
of paroxysms since 26 January had risen to 34. Since the prevailing
wind direction in the past few days has been to the east and southeast,
the town of Zafferana has suffered most from the ash and lapilli falls
caused by the paroxysmal episodes. On the forenoon of 19 February,
a heavy rain of pyroclastics occurred, leaving a continuous blanket
of scoriae on roads, roofs and cars. Some of the fragments falling
in Zafferana had diameters of several centimeters.
Photos
of the 14 February 2000 paroxysm:
The view from 900 m distance
A
detailed description of the event is available on an archived
previous Etna
updates page. All photos are by Boris Behncke
|
1 |
2 |
Initial
stage of the paroxysm: a cherry red lava fountain is jetting from
a vent low on the NNE flank of the SE Crater cone (which is seen
in the left photo with the fountain at right). It is shortly after
1600 h, and the activity is rapidly increasing |
3 |
4 |
Within
one or two minutes, the entire SE Crater cone disappears behind
a dense curtain of gas and ash, and a large eruption column begins
to develop, drifting south under the strong northerly wind, right
towards Torre del Filosofo (which is out of the images to the
left) |
5 |
While
bombs and scoriae begin to fall all over the cone and a dense
gas plume drifts around its eastern side from the vents on the
northern flank, new fountains are bursting from vents in the summit
area: a red glow is visible in the left part of the photo, where
a lava fountain shoots obliquely to the south |
6 |
7 |
At
the height of the paroxysm, a large lava fountain (seen glowing
in its lower portion) rises up to 400 m from the summit vent,
and the eruption column above the crater rapidly rises several
kilometers high |
8 |
9 |
About
10 minutes after its beginning, the paroxysmal activity begins
to wane. The eruption column is less dense, and the SE Crater
cone reappears from its veil of ash and gas |
10 |
11 |
The
paroxysm has reached its final stage. The lava fountains break
down and for a few minutes ash continues to be emitted from the
summit vent of the SE Crater. Lava is still flowing down in several
streams on the southern (left) side of the cone |
12 |
13 |
About
10 minutes after the end of the paroxysm, Behncke and Scarpinati
reach the still flowing lava at the southern base of the SE Crater
cone. Lava is slowly advancing over lavas emplaced during the
previous parosyxms, and lava continues to spall off the steep
southern flank of the cone (in the background) |
14 |
A
detailed view of the lava front advancing slowly near the southern
base of the SE Crater cone |
20
February 2000 update.
While eruptive paroxysms are occurring at the Southeast Crater about
once or twice daily. The latest three of which I know took place on
18 February at shortly before 1600 h (local time=GMT+1), on 19 February
at about 0950 h and at around 0400 h on the 20th. The number of paroxysms
since 26 January is now over thirty.
Analysis of photos and spectacular video footage taken during some
of the paroxysms of the past seven days reveals much interesting detail
about these events and their dynamics, which will be discussed below
for the case of the two eruptive episodes on 15 and 16 February. Furthermore,
some words will be said here about safety in the summit area and observation
possibilities during eruptive paroxysms.
Paroxysmal
eruptive episodes of 15 and 16 February 2000.
The following describes in more detail the eruptive episodes at the
Southeast Crater (SE Crater) on the afternoon of 15 February and on
the afternoon of 16 February, which were observed in detail by several
persons, some of which know the volcano well and have witnessed other
important eruptive events in the past. Marco Fulle, who frequently
collaborates with "Italy's Volcanoes" and "Stromboli
On-line", was at the Torre del Filosofo mountain hut on both
occasions (he did not observe directly the paroxysm on the morning
of 16 February). This mountain hut, which was erected in the late-1960s
on a small hill, stands about 1 km south of the SE Crater and has
been until now spared from destruction by lava flows, but in 1971
and 1989 lava flows came very close to the building, scratching one
of its corners in the latter occasion. During the summer season hundreds
or even thousands of tourists are brought to this place by the jeeps
of the SITAS company which is in charge of the cable car and the tourist
jeeps on the southern flank of Etna. It is generally considered a
safe place because it has been affected only rarely by heavy falls
of pyroclastics during major explosive eruptions at the summit craters.
By the afternoon of 15 February, the SE Crater had been in a state
of absolute calm since the eruptive episode witnessed by Behncke and
Scarpinati shortly after 1600 h on 14 February. A strong wind blew
towards east, so that in the case of renewed activity, most of the
scoriae and ash would have been deposited to the east of the crater.
After nearly 26 hours of quiescence, increased gas output was noted
by a member of a group of about 7 persons staying at Torre del Filosofo,
shortly before 1800 h. This was followed by the appearance of weak
Strombolian bursts at the summit vent of the SE Crater cone. There
does not appear to have been any activity at the vent low on the N
flank of the cone, which had been the first to erupt during the previous
paroxysmal eruptive episode. Strombolian bursts continued for about
five minutes at increasing frequency and intensity from at least two
vents, the more northerly of which ejected bombs obliquely onto the
E flank of the cone. Then the activity became more and more continuous,
and incandescent pyroclastics were thrown at ever greater distance,
mainly onto the eastern flank. Shortly after 1800, a glowing spot
appeared immediately below the southern lip of the summit vent, which
lies in a deep notch persisting since the beginning of episodic eruptive
activity at the SE Crater in late January. A small pulsating fountain
rose from the vent, initially only a few meters high, but gaining
rapidly in height and vigor. Within shortly a very small lava flow
began to leak from this vent, slowly extending downslope. At the same
time, the noise of the activity began to change from the initial intermittent,
relatively flat, gushing noise of the Strombolian activity to a continuous
loud and deep roaring.
The activity increased rapidly. Within one minute or two from the
appearance of the southern vent, huge jets of fluid lava rose from
that vent and, even more vigorously, from the vents at the summit
of the cone. The volume of lava flowing from the southern vent increased
rapidly, at times generating surges overriding the slower, more advanced
part of the flow. The entire cone was soon covered by incandescent
pyroclastics. The observers, who still stood in the flat area to the
N of the Torre del Filosofo building, saw a curtain of falling glowing
bombs and scoriae extending rapidly towards them, and the sky above
them all at once was full of red-hot pyroclastics flying in their
direction. While beating a hasty retreat to find shelter at the Torre
del Filosofo building, cameraman David Bryant filmed bombs falling
around and behind him; some of them had diameters of tens of centimeters,
and many were seen bouncing from the ground and bursting into smaller
fragments. Fortunately it was only one particularly strong, oblique
jet of lava from the southern vent, which sent bombs to as far as
the Torre del Filosofo, "if it had lasted 30 seconds longer,
we wouldn't be here anymore", as Bryant expressed.
Bryant managed to film the ongoing activity from relative safety behind
an overhanging roof of the building, placing himself on a large accumulation
of snow (in January, heavy snowfalls had buried the building almost
to its roof) on its southeastern side. While still increasing, the
activity had now gained a state of relative stability, with all fountains
(at least those visible from Torre del Filosofo) rising vertically.
The largest fountain came from the summit vent(s), and from Bryant's
video footage as well from estimates made by other observers, including
Behncke who watched the activity from Catania and Scarpinati, who
made observations from Acireale, the fountain height was consistently
500-600 m with bursts reaching 800 m above the summit. In this period,
the lower central portion of the main fountain had a flame-like appearance,
with brighter and darker portions mixing in a turbulent uprush. The
entire cone was covered with incandescent material, some of which
developed secondary flowage, while a broad lava flow gushed down the
southern flank, fanning out at its base.
About 10 minutes after the onset of violent fountaining, the fountains
rising from the cone began to appear slightly weaker, although the
continuous uprush continued for some time. Then, from one moment to
another, the fountains stopped, while thousands of incandescent projectiles
continued to fall in a dense shower onto the cone. After a few seconds,
new lava jets appeared, but they were only short-lived and much weaker
than the earlier fountains. The cone eventually stood there quiet,
covered all over with incandescence, and lava continued to flow on
its southern flank. As the activity ceased, the members of the group
at Torre del Filosofo screamed and laughed with relief. Each of them
had lived through moments of extreme apprehension when the rain of
bombs had extended around and beyond them.
These eyewitness
accounts, and observations made by the author of this site during
the paroxysm on the afternoon of 15 February, indicate that there
is no safety at Torre del Filosofo during the ongoing paroxysmal eruptions
from the SE Crater. The group surprised by the rain of bombs during
the 15 February paroxysm fortunately had stayed close to the building,
so that they reached shelter in a few seconds. Had they stayed a bit
farther away, they might have encountered very serious problems.
For about 10 minutes after the cessation of the paroxysmal activity,
minor Strombolian activity occasionally resumed for short periods.
The most interesting thing at this stage was the continuing flow of
lava from a crack on the southern flank of the cone. The surface of
lava in the crack dropped consistently, indicating that the conduit
virtually ran empty through the crack. This crack apparently had opened
at the height of the paroxysm, but it is difficult to judge if fountaining
had occurred also lower on the flank, since this area had been entirely
hidden from view by the dense curtain of falling pyroclastics.
The 15 February paroxysm was certaily the most vigorous activity produced
at the SE Crater since its reawakening on 26 January. Nonetheless
it was of minor proportions compared to events like the 4 September
1999 paroxysm at the Voragine, and its most dramatic effects were
limited to a small area immediately around the crater.
The paroxysm on the afternoon of 16 February was, though spectacular,
much less intense than that of the evening before. Fountain heights
were only about 300 m, and the paroxysmal activity lasted only about
7 minutes.
Based on
what has been said in the preceding paragraphs, people hoping to see
the eruptive activity at close quarters are advised to stay always
away from the direction of the main fallout (downwind from the SE
Crater). During the paroxysm on the afternoon of 14 February, clasts
up to 10 cm in diameter fell on the Piano del Lago, the relatively
flat area about 2 km south of Torre del Filosofo. Fragments of this
size hurt badly if falling on unprotected parts of a human body. Visitors
should maintain a reasonable distance from the crater, possibly of
at least 3 km (such as the Montagnola area, near the upper cable car
station, if this is not downwind from the crater). In the case of
being surprised by a paroxysmal eruptive episode, one should try to
find shelter, either at a building (although close to the SE Cratere,
there's nothing except the Torre del Filosofo mountain hut), or behind
a large rock. However, any unexperienced visitor of Etna is advised
to stay near the upper cable car station, the activity can be well
observed from there.
Several
other web pages covering the October-November 1999 eruptions of the
Bocca Nuova have recently been posted; these contain photos and movie
clips of some of the most spectacular moments of that period.
A
photo gallery covering the period September-November 1999 (with photos
by Boris Behncke and Giuseppe Scarpinati)
Photos
of the eruptive activity, 26-31 October 1999, by Tom Pfeiffer (University
of Arhus, Denmark)
Photos
by Marco Fulle, 17-23 October 1999, at Stromboli On-line - Marco at
his best
Very
impressive video clips, taken by Roberto Carniel on 17-23 October
1999, at Stromboli On-line
Photos
by Juerg Alean, of 1 November 1999, at Stromboli On-line
Video
clips, taken by Juerg Alean on 1 November 1999, at Stromboli On-line
A
page by Charles Rivière, France, with many photos of the summer
and autumn of 1999 (in French)
visitors counted since 12 February 1999
(This page has received an incredible 4362
hits during the week of 24-30 October 1999. 4430
hits were counted the week after. However, this is nothing compared
to the more than 1000 visitors daily in mid-February 2000)
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Page set up on 27 May 1997, last modified
on 26 February 2000