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WARNING:
Access to the summit area is VERY
DANGEROUS and ACCESS TO THE SUMMIT CRATERS IS FORBIDDEN.
The regime of eruptive activity at the Southeast Crater has
changed once more, and episodes of vigorous explosive and effusive
activity might occur with relatively little warning. Guided
excursions on the south flank that end at the Torre del Filosofo,
at about 2900 m elevation, have resumed in mid-March, and on
the north flank excursions arrive at 3100 m elevation, on the
E side of the main summit cone. Tourists
should make excursions only with the mountain guides and NEVER
GO ALONE, even though this will not satisfy the wish
to see what's going on at close range. Besides this, weather
conditions are often unstable: strong wind, snow or rain and
clouds are occuring frequently in the summit area, even during
the summer, and one can get easily lost. The mountain guides
can be contacted at the cable car (near the Rifugio Sapienza)
on the southern side of Etna (phone: 095-914141), or (during
the summer) at the hotel "Le Betulle" at Piano Provenzana,
on the northern side (phone: 095-643430). There
is now a new web site giving more information about guided excursions
on Etna.
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The
latest update is near the bottom of this page
3 July 2001 update.
Increased
degassing from the Northeast Crater is occurring as of 3 July, early
afternoon; this phenomenon has been visible throughout the morning
of this day. Some of the recent paroxysmal eruptive episodes from
the Southeast Crater have been preceded by increased emissions (gas,
at times with ash) from the Northeast Crater, and the current degassing
might be a forerunner of the expected 12th Southeast Crater paroxysm,
which seems to be coming after a longer repose interval than any of
its predecessors. Weather cloud is rendering visual observations difficult
at times, but it is hoped that toward the evening the summit area
will clear and any eruptive activity will be plainly visible.
More detail about the timing of the 30 June eruptive episode at the
Southeast Crater has become available. The event occurred during bad
weather which rendered visual observations impossible, and the following
is based on observations of volcanic tremor. Information was kindly
supplied by Marco Neri (Istituto
Nazionale di Geofisica e Vulcanologia, Sezione di Catania) by
oral communication and is preliminary. Supplementary information comes
from Dominique Lauper, Switzerland who was near the summit at the
time of the event.
Lava outflow was first observed during the evening of 29 June, when
the cloud cover over the summit of Etna had lifted temporarily. Lauper
noted the flowing lava at about 2300 h (local time=GMT+2). Mild Strombolian
activity presumably began at around 0400 h on 30 June and progressively
increased over the next 4 hours. The phase of most vigorous (explosive
and effusive) activity occurred between 0800 and 1105 h, but showed
a slightly decreasing trend starting at 0930 h. Lauper, who stayed
near the Torre del Filosofo mountain hut, did not see anything due
to dense cloud cover, but the noise level increased significantly
at 0705 h, when bombs were heard impacting on the flanks of the SE
Crater cone. After 1105 eruption-related seismicity decreased notably,
although the noise level audible at Torre del Filosofo reached the
highest levels between 1230 and 1300 h, possibly related to strong
degassing at the end of the paroxysmal phase. The eruptive episode
was essentially over shortly after 1600 h. Lauper observed continued
lava effusion between 1600and 1800 h, at a fairly high effusion rate.
By 2100 h, however, all lava effusion had stopped. When the clouds
dissipated on the evening of 30 June, no incandescence was visible
anywhere on the volcano, as observed at about 2130 h by Behncke from
Catania.
Although it is not known to what proportion the activity was shared
by the various eruptive vents at the SE Crater, it is assumed that
the character of this latest paroxysm was similar to that of its predecessors.
On the evening of 1 July, Behncke noted the continued absence of incandescence
when observing the volcano from the "Ulysses harbor" in
the NE part of Catania. The situation was identical on the evening
of 2 July.
Some general conclusions can be drawn at this point about the current
series of eruptive episodes at the SE Crater. None of the 11 paroxysms
that have occurred so far has reached the dimensions of those observed
one year ago at the same crater. According to Neri, the "magnitude"
of the current eruptive phenomena is only half or one-third of that
of the 2000 events, which regards especially the explosivity of the
paroxysms. In 2000, most eruptive episodes produced sustained lava
fountains from the summit vent and in many cases also from vents along
fissures on the S and NNE flanks of the SE Crater cone. Fountain heights
were, except in a few cases, impressive: 200-500 m were common, and
some paroxysms produced fountains up to 1000 m high. In 2001, true
lava fountains have been observed mostly at the "Levantino"
vent, on the NNE flank of the SE Crater cone, and they have reached
only "modest" heights of 50-300 m. The summit vent did produce
lava fountains during some of the recent paroxysms, but in most cases
they did not last long, and often that vent produced discrete (though
violent) Strombolian bursts in rapid succession rather than sustained
fountains. The height of ejections from this vent rarely exceeded
500 m. Flow lengths are more or less similar in both series of paroxysms
(maximum 2-3 km from the source vents), but in 2001 all effusive activity
is limited to the NNE side of the SE Crater cone, whereas in 2000
most paroxysms produced lava from both the NNE and S sides of the
cone.
Tephra production during the current series of eruptive episodes has
been very minor in comparison with the paroxysms of last year. The
most significant tephra emission occurred during the paroxysm on the
morning of 11 June (see
the spectacular photos on the web site of Thorsten Boeckel). Only
very light ash falls have occurred so far in inhabited areas on the
flanks of the volcano. In 2000, towns and villages, especially in
the E sector of Etna received repeated heavy showers of scoriaceous
lapilli which caused considerable logistical and economic problems
to the affected population.
So Etna is once more providing a haunting though essentially harmless
show at its SE Crater, but the magma involved seems to be less voluminous
and/or gas-rich than last year. This show is occurring almost six
years after the beginning of near-continuous eruptive activity at
the summit craters, and nearly ten years after the beginning of the
last flank eruption. More summit activity might be expected for years
to come, but sooner or later there will be new flank eruptions, and
then the show will become dangerous.
5 July 2001 update.
The 12th
eruptive episode in 30 days at the Southeast Crater finally occurred
on the evening of 4 July, after 4.5 days of quiet. Observations were
made by Giuseppe Scarpinati (Italian delegate of the Paris-based Association
Volcanologique Européenne, or "L.A.V.E."), whose
report is summarized below.
According to local
mountain guides, lava effusion from the "Levantino" started
at about 1100 h (local time=GMT+2), forming two lava flows oriented
toward NE (in the direction of the Pizzi Deneri) and SSE.
Scarpinati arrived at the Pizzi Deneri at 2115 h, by then modest Strombolian
activity occurred at the summit vent of the SE Crater and the two
lava flows extending from the "Levantino" were gradually
advancing. The NE flow by then was about 150 m long, the ESE flow
appeared somewhat longer.
At 2200 the Strombolian activity at the summit vent stopped temporarily,
then at 2230 resumed in a much more vigorous manner, but lava emission
and spattering at "Levantino" ceased at about the same time,
and the two lava flows stopped advancing.
Very powerful, "cannon shot"-like explosions occurred now
at the summit vent, producing jets inclined in all directions and
up to 400-500 m high. They occurred in rapid succession, several per
second, and for a period large magma bubbles burst into huge fragments
that fell down to as far as the base of the SEC cone.
At 2345 h explosions at summit vent declined in strength, but at the
same time activity at "Levantino" increased instantaneously
with vigorous spattering, producing a minor new flow to NE and leading
to the resumption of the ESE which rapidly extended to 1500 m. A dense
tephra column rose from summit vent, obscuring the full moon, and
leading to ash falls on the SE flank of Etna. Fine ash fell as far
as Acireale including fine threads of "Pele's hair" 3-5
mm long.
At 0045 h there was a notable diminution of the activity and at 0100
Strombolian activity at summit ended; weak spattering continued for
a while at the "Levantino" and slow lava effusion was ongoing
at 0200 h when Scarpinati left his observation post.
This eruptive episode came after a repose period that was much longer
than those separating the preceding 11 paroxysms. Further eruptive
episoded might be expected in the near future, but the repose intervals
between them are expected to be highly irregular, so that it is impossible
to make any considerations about when they might occur.
NOTE: No updates will be posted on this page
until late July, since I have to return to Tuscany for a few weeks.
In the meantime, you will find information about Etna's activity on
the following web sites: Stromboli
On-line and the site of Charles
Rivière which is in French, but usually very up-to-date.
The Poseidon (INGV) web site is currently offline (no web live-cam,
unfortunately) but maybe the indicated web sites will give information
once it is back on-line.
The
recent eruptive activity at Etna's summit craters is featured on several
web pages that contain additional information and highly spectacular
images. Some of them (Poseidon/INGV, Charles Rivière and Stromboli
On-line) have regular updates.
Etna
in 2000 - a list of all paroxysms at the SE Crater since 26 January
and photos (this site)
Etna
in 2000 - various pages at Stromboli On-line with photos and movie
clips of SE Crater paroxysms and Bocca Nuova gas rings: most photos
are of Marco Fulle, the artist photographer among us
Extremely
spectacular video clips, taken by British cameraman and film maker
David Bryant on 15 February 2000
At
"Italy's Volcanoes" -
At Stromboli On-line
An
interview with Boris Behncke, made in late February 2000 by a BBC
team
and a video
clip (RealPlayer)
Photos
of the eruptive activity, 15-23 February 2000, by Tom Pfeiffer (University
of Arhus, Denmark) - scroll to bottom of page
Alain
Catté (Association Volcanologique Européenne) has photos
of Etna
from many years
Photos
of an eruptive episode on 13 February 2000, posted on the web site
of the Association Volcanologique Européenne, Paris, France
Thorsten
Boeckel's web site (Germany) with photos and movie clips of several
paroxysm of the SE Crater in February, April and June 2000
A
small web page reporting on Etna's current activity - and check what
happens to your cursor on that page...
Charles
Rivière's Etna home page, with many photos and video clips
(the most recent of the paroxysm of 5 May 2000), frequent updates,
and other, highly interesting items (in French and English)
