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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
25 May 2001 update.
The Southeast
Crater has remained active through 25 May, with lava effusion from
a small cone (named "lava cone" hereafter) on its NNE flank,
and mild Strombolian activity at its summit vent. This activity has
been remarkably regular since the stronger eruptive episode of 9 May
(see the previous updates) and
possibly will continue in a similar manner for some time to come,
marking the return at Etna to the characteristic persistent summit
activity.
Observations were made frequently by Boris Behncke (Dipartimento di
Scienze Geologiche, University of Catania) and geologists of the Open
University Geological Society (Mainland Europe) during the reporting
interval (19-24 May), including a brief summit visit on 21 May which
had to be cancelled due to an extremely strong southerly wind, and
a very successful visit to the site of the current activity on 23
May. Further observations were made by geologists of the Dipartimento
di Scienze della Terra, University of Perugia, Italy, and have been
kindly been made available by Vittorio Zanon.
On the evening of
19 May, the Perugia University geologists observed that the active
lava flow from the lava cone on the NNE flank of the SE Crater cone
extended about 1.2 km toward the Valle del Bove, and a fluctuating
glow at the source vent indicated that there might have been mild
spattering at the vent. No explosive activity was seen at the summit
vent of the SE Crater that evening.
On the afternoon of the next day (20 May) the geologists from Perugia
reached the Torre del Filosofo mountain hut (about 1 km south of the
SE Crater) in spite of the strong wind and noted that Strombolian
activity had resumed at the SE Crater summit vent, and bombs rose
up to 120 m above the vent, with some falling onto the S flank of
the cone. The geologists then visited the active eastward-directed
lava flow, approaching around the E side of the SE Crater cone, and
found it quite vigorous, while a smaller lobe of lava was advancing
slowly in a southerly direction. At about the same time Behncke observed
the flow from the "Mareneve" road near the village of Fornazzo
(on the E side of Etna; about 7 km from the SE Crater), which was
well visible thanks to the plume of gas it was emitting along its
entire length; the front was estimated at a distance of about 2 km
from the vent. At about 2045 h (local time=GMT+2), the geologists
from Perugia observed a sudden increase in the effusion rate, which
were accompanied by stronger and more frequent Strombolian explosions
at the summit vent of the SE Crater. This was immediately followed
by a surge of fresh lava which cascaded down on top of the earlier,
still-active eastern flow. Shortly afterwards, Behncke and the Open
University Geological Society (OUGS) geologists were back on the "Mareneve"
road near Fornazzo and saw the fresh lava tongue advance rapidly on
top of the cooling earlier flow lobe, apparently following an established
flow channel. Meanwhile the Perugia geologists had retreated somewhat
toward the Torre del Filosofo hut and observed the effusive vent "bulging
and then cracking open" on its southern side, generating a rock
avalanche, followed by several rivulets of lava that spilled down
that side of the lava cone. The new lava lobe advanced eastward at
an estimated speed of 250-400 m/h.
Behncke and the OUGS geologists observed that a second major lava
flow ran from the lava cone toward NE, in the direction of the Pizzi
Deneri, reaching a length of slightly less than 1 km. This flow appeared
less vigorous than the eastern flow and was partly hidden behind the
ridge of the lava field formed on the NNE side of the SE Crater cone
since late January.
Strombolian bursts occurred frequently at the summit vent of the SE
Crater, with bombs rising as much as 270 m above the vent (observations
made by the Perugia geologists). Observation by Behncke and the OUGS
scientists ended at about 2130 h, but the geologists from Perugia
stayed on the upper S flank of Etna and noted a decrease in the intensity
of the Strombolian activity at about 2300. No explosive activity was
observed for the rest of the night, but a bright glow was visible
in the area of the effusive activity.
On 21 May, Behncke and the OUGS geologists made a first attempt to
reach the site of the eruptive activity but had to resign due to the
ferocious "Scirocco" wind that made any stay in the summit
area highly uncomfortable. However, that evening observations were
made from Linguaglossa, a town on the NE flank of Etna. Both main
flows (the eastern and NNE flows) remained active, and after nightfall
Strombolian explosions were again seen at the summit vent of the SE
Crater. Later that night the Perugia geologists observed (from Acireale,
SE of Etna) that the explosive activity had again subsided, while
the eastern lava flow was still active and incandescent for a length
of about 1.5 km.
On 22 May the activity continued in much the same manner, with sporadic
Strombolian bursts from the SE Crater summit vent and continued lava
outflow, feeding both the eastern and NNE flows, but local mountain
guides reported that the latter was slowing.
Weather conditions improved markedly on 23 May, permitting a visit
to the SE Crater and the effusive vent and the associated lava flow-field.
During this visit, which lasted from about 1500 to 2200 h, the NNE
flow had diminished considerably, with several sluggish lobes of lava
moving across the upper part of the lava flow-field; these lobes did
not advance further than about 500 m, and all were fed by ephemeral
vents lying 150-200 m from the main effusive vent.
In contrast, a vigorous lava flow originated at the summit of the
very steep lava cone (which was about 50-70 m high), located about
half way down the NNE flank of the SE Crater cone. This flow ran down
the E side of the cone, forming a spectacular cascade about 10 m high.
The speed of the flowin lava was estimated at 5-7 m per second, and
the effusion rate was several cubic meters per second (the 20 May
update of the Poseidon monitoring network gives 2.5-4.5 cubic meters
per second for 18 May, a value that corresponds well with the 23 May
observations). This flow split into several branches at the base of
the lava cone, all of which were directed toward the Valle del Bove.
The lava issued from the vent quietly, without any spattering, although
a loud hissing noise was produced by high-pressure degassing at the
vent. On several occasions a sudden increase in the intensity of the
degassing noise was immediately followed by a brief surge of higher
lava output. Every few minutes huge blisters or submerged boulders
travelled on top of the flowing lava, rushing down the lava cascade
on the E side of the lava cone.
The summit of the vent nearly continuously produced mild Strombolian
explosions during the 7 hours visit. Most of the bombs ejected by
these explosions rose only a few tens of meters above the vent, but
every now and then bombs reached heights of 100 m or more. The Strombolian
explosions did not occur regularly, but were clustered, as had been
already observed repeatedly during the preceding days. For 5-10 minutes,
explosions would occur every 3-10 seconds, then there would be a relatively
quiet interval of several minutes during which there were no or only
few and weak explosions, which was in turn followed by a new series
of more vigorous explosions. None of the explosions produced any ash.
After nightfall, from an observation point located about 600 m north
of the summit of the SE Crater, all explosions were seen to start
with a rapidly intensifying glow before bombs began to appear above
the crater rim. This indicates that the explosions occurred at a certain
depth within the conduit, possibly at the same elevation of (or slightly
higher than) the effusive vent on the lava cone (about 150 m below
the hightst point of the SE Crater rim).
No eruptive activity was observed at the other summit craters on that
day. During the previous weeks the activity at these craters had shown
very low levels.
On the evening of 24 May, lava emission and irregular Strombolian
explosions at the SE Crater continued in much the same manner as during
the preceding days. The active eastern lava flow was continuing to
flow as of early 25 May, but bad weather rendered visual observations
difficult and brought a light dusting of snow to Etna's summit area.
The observations described in the previous paragraphs indicate that
the eruptive activity at the summit of Etna is presently quite stable
for the first time since about 2 years. This activity resembles much
that of the 1950s and 1960s when persistent Strombolian and effusive
activity occurred nearly continuously at the Northeast Crater. However,
this activity is not easy to observe for the normal Etna visitors.
The best way to see some of the ongoing activity is to take the sunset
tours offered on the southern and northern sides of Etna (near the
Rifugio Sapienza on the S side and at Piano Provenzana on the N side)
or to drive from the village of Fornazzo on the "Mareneve"
road in the direction of Piano Provenzana after nightfall. It must
be once more emphasized that non-authorized persons are not allowed
to go to the summit craters, and controls have been intensified after
last week's fatal accident at the Bocca Nuova when a Spanish tourist
disappeared in one of the active pits of that crater.
29 May 2001 update.
Eruptive
activity has continued at the Southeast Crater without significant
variations during the past four days, although bad weather at times
has made visual observations difficult. With the return of good visibility,
nighttime observations on 28-29 May have revealed continued lava effusion
from the vent on the NNE flank of the SE Crater cone and mild Strombolian
activity at the summit vent of that crater. The effusive vent may
have shifted about 50 m further upslope on the flank of the cone,
as observed by Giuseppe Scarpinati on the evening of 28 May. An active
lava flow directed eastward, toward the Valle del Bove, was seen to
be partially flowing through tubes for 800 m; below that lava issued
from several ephemeral vents feeding about three active lobes that
extended about 1 km further. No incandescence was observed at any
of the three other summit craters.
During daylight on 28 and 29 May a dense gas plume was seen issuing
from the SE Crater's summit vent, while lesser gas was produced by
the Bocca Nuova. During the January-August 2000 eruptive period of
the SE Crater degassing was virtually absent between eruptive episodes,
and only weak fumarolic activity was observed during the months between
September 2000 and January 2001. Since the resumption of effusive
activity from the vent on the NNE flank of the SE Crater cone in late
January, a persistent gas plume has been present at the summit vent,
but it has grown much denser since the eruptive episode on 9 May.
1 June 2001 update.
There
has been no significant change in the style and magnitude of eruptive
activity at the SE Crater in the past few days, and lava continues
to flow from the "lava cone" on the NNE flank of the SE
Crater cone, accompanied by discontinuous Strombolian activity at
the SE Crater summit vent. The activity was observed by Roberto Carniel
and Marco Fulle (Stromboli On-line), Tom Pfeiffer and numerous other
local and international scientists (including Andy Harris and Jon
Dehn) on several occasions over the past 4 days or so. The overall
effusion rate was estimated at an astonishing 5-10 cubic meters per
second, which is very high for Etna's persistent summit activity.
Occasionally pressure waves were generated by explosions at the summit
vent of the SE Crater, and on 31 May mountain guides reported that
such explosions occurred on a rate of one every 10 minutes, throwing
bombs about 100 m above the crater rim.
There is also some fresh activity occurring in the Bocca Nuova (probably
weak Strombolian explosions in one or both of its active pits), and
degassing has increased at the NE Crater, which displayed mild Strombolian
activity in April-May 2000 and produced ash emissions in August 2000.
This and the fairly high rate of lava emission from the SE Crater's
"lava cone" might indicate that more magma is currently
rising up through the central conduit system of Etna than during the
past months. In the six years since the beginning of the current summit
eruptions (no flank eruption has occurred since the major 1991-1993
eruption), voluminous batches of fresh magma have risen repeatedly
to the summit craters, generating episodes of spectacular eruptive
activity at all four summit craters. If it is true that a new magma
batch is nearing the surface, we soon might see yet another act in
the incredibly multifaceted volcanic show that began in July 1995.
6 June 2001 update.
Eruptive
activity has continued at the SE Crater without significant changes
except for the direction of active lava flows. On the evening of 5
June, an active flow lobe extended NE, in the direction of the Valle
del Leone (which is actually the northern part of the Valle del Bove).
Observation by Giuseppe Scarpinati from Acireale (SE of Etna) revealed
that this flow is well-fed, incandescent for most of its length, and
seems to be among the longest lobes that have developed so far during
the current episode of effusive activity at the SE Crater. There was
only very weak Strombolian activity at the summit vent of that crater
during Scarpinati's observations, but such activity has been irregular
throughout the past 4 weeks, with periods of vigorous Strombolian
activity alternating with such periods with little or no explosions.
There has also been some Strombolian activity within the Bocca Nuova
lately, although the floors of its two active pits seem still to be
at much greater depths than in late March (the most recent visit to
that crater by Behncke and Scarpinati). It has also been reported
that a small pyroclastic cone has grown recently (possibly in late
May) on the floor of the active pit of the NE Crater, but there have
been no reports about ongoing eruptive activity at that crater.
7 June 2001 update.
Eruptive
activity at the Southeast Crater stopped sometime during 6 June but
resumed spectacularly during the following night.
During the early morning hours of 6 June, Giuseppe Scarpinati (Italian
delegate of the Paris-based Association
Volcanologique Européenne, or "L.A.V.E.") observed
the volcano from his home in the town of Acireale, lying about 18
km SE of Etna's summit. At that time an active lava flow from the
effusive vent on the NNE flank of the SE Crater cone had reached a
length of about 2.3-2.5 km and was advancing toward the Valle del
Leone. Scarpinati observed large blocks detaching from the flow front
and rolling down the steep slope. There was only very weak explosive
activity at the summit vent of the SE Crater, but a faint glow could
be seen at the Bocca Nuova.
At nightfall on the same day, Scarpinati saw what he described as
a "dead volcano". There was no incandescence in any place
where before there had been the spectacular and very active lava flow,
indicating that effusive activity had stopped already many hours before.
Neither was there any sign of explosive activity except a very faint
glow at the Bocca Nuova, but Scarpinati was not even sure about this.
It seemed that all activity had completely stopped at the SE Crater,
which seemed quite strange after the vigorous activity observed during
the past few weeks and on that same morning.
The pause was not to last long. Lava apparently reappeared at the
effusive vent on the NNE side of the SE Crater cone at about 2300
h (local time=GMT+2), and this was soon joined by Strombolian bursts
from the summit vent of that crater. Scarpinati made observations
between 0245 and 0315 h on 7 June, by which time an active lava flow
extended about 800 m toward E or NE, and several smaller lobes occasionally
spilled from the effusive vent. The activity was characterized by
surges that occurred about once per minute, but Scarpinati did not
see any lava spattering at the effusive vent. At the summit of the
SE Crater, however, vigorous Strombolian activity produced explosions
every 10 seconds or so, with jets of incandescent ejecta rising up
to 300 m above the summit of the crater. During his 30 minutes of
observation, Scarpinati noted a decrease in the lava output, but other
observations made before dawn on 7 June revealed that the activity
(both effusive and Strombolian) continued vigorously through at least
0600 h. At 0800 h, Scarpinati noted forceful ash emissions at the
summit vent of the SE Crater, but these emissions disappeared during
the following hour. A dense gas plume continues to be emitted from
the effusive vent on the NNE flank of the SE Crater during the forenoon
of 7 June, and it is assumed that lava effusion is continuing.
8 June 2001 update.
After
the vigorous effusive and Strombolian activity of yesterday (7 June)
morning, the Southeast Crater has once more settled into a state of
total inactivity during the late afternoon of yesterday, and no eruptive
activity has been observed since then (that is, through the late forenoon
of 8 June). This is an exact repetition of the eruptive quiet observed
between the morning and late evening of 6 June, which lasted up to
20 hours. The activity might therefore resume soon, possibly before
midnight on 8 June, and be as vigorous as (or even more vigorous than)
the previous episode of lava emission and Strombolian activity at
the SE Crater. Although at the moment this hypothesis is nothing else
than speculative, this change in the eruptive behavior of the crater
could mark a return to episodic activity, similar to that observed
in 2000, and eruptive episodes might be much more violent than the
activity observed in the past few months. That would also mean that
visits to the summit area are becoming more dangerous, and it is recommended
that no one approach the area of the recent lava emission at the SE
Crater, since eruptive episodes might start quite instantaneously.
9 June 2001 update.
The "forecast"
made in the previous (8 June) update was fully correct except for
the precise timing: a new eruptive episode has indeed occurred at
the Southeast Crater, but rather than occurring "before midnight"
on 8 June, most of it occurred AFTER midnight on 9 June.
The first indications of the imminent eruptive episode were observed
by the ceaselessly alert Giuseppe Scarpinati (Italian delegate of
the Paris-based Association
Volcanologique Européenne, or "L.A.V.E.") at
about 2200 h on 8 June (local time=GMT+2) from his home in Acireale.
At this time a small incandescent spot was visible at the NNE flank
vent of the Southeast Crater, but there were no indications of flowing
lava or any type of explosive degassing. Lava began to issue in earnest
from the NNE flank vent sometime after midnight on 9 June, and during
the following hours the activity gradually increased, until, by about
0345 h, lava fountains were continuously rising from the NNE flank
vent, and Strombolian bursts occurred at the summit vent of the crater.
Scarpinati was back observing the activity at about 0410 h when continuous,
Hawaiian-style lava fountaining occurred at the NNE flank vent and
Strombolian bursts continued at the summit vent. Two well-developed
lava flows had already formed, one toward the Valle del Leone which
was between 1 and 1.5 km long (the longer value has been given on
the web
site of Charles Rivière), while the second, directed toward
southeast, was only a few hundred meters long and split into several
lobes. This latter flow had apparently stopped moving already and
was gradually cooling.
After 0500 h the fountaining at the NNE flank vent decreased in intensity
and was soon replaced by discrete Strombolian bursts which occurred
about every 1.5 seconds, until there was a further reduction in the
level of activity at about 0530 h. In this late phase, Scarpinati
observed the appearance of a glowing area between the NNE flank vent
and the summit vent of the Southeast Crater, which, however, never
started to produce true eruptive activity.
By about 0800 h, the activity had declined to low levels, and lava
outflow from the NNE flank vent had essentially ceased. However, during
the following hours Etna's summit area remained volcanically active.
By 1100 h, the Bocca Nuova's northwestern vent produced frequent explosive
ash emissions, and Strombolian explosions were occasionally visible
at the summit vent of the Southeast Crater.
This eruptive episode occurred two days after its predecessor and
was very similar in character, though slightly stronger (lava fountains
from the NNE flank vent rose up to 150 m high). A main feature which
distinguishes these events from those of last year (when there were
no less than 66 powerful eruptive episodes at the Southeast Crater
in the course of 7 months) is that the main seat of activity is now
the NNE flank vent, while the summit vent of the SE Crater does not
produce tall, sustained lava fountains, but only vigorous Strombolian
explosions.
This latest event confirms the assumptions expressed in the previous
updates on this page that the Southeast Crater has returned to episodic
eruptive activity and may continue in this manner for some time to
come. Unfortunately the dynamics of magma ascent, storage and explosive
degassing are still poorly understood, and it remains largely mysterious
why there are such changes from episodic to continuous and then again
episodic activity such as observed in the course of the past 18 months
at the Southeast Crater.
11 June 2001 update.
Two days
after its latest eruptive episode (9 June), the Southeast Crater erupted
once more on the early morning of 11 June, for the third time in 5
days. This event might have been stronger than the previous one, which
means that the intensity of eruptive episodes at the Southeast Crater
is progressively increasing.
On 10 June, Etna remained in a state of complete quiet. Giuseppe Scarpinati
(Italian delegate of the Paris-based Association
Volcanologique Européenne, or "L.A.V.E.") visited
the summit area in the late forenoon and described the SE Crater and
the growing cone on its NNE flank as "absolutely dead",
while there were sporadic, deep-seated explosions occurring at the
NW vent of the Bocca Nuova. At nightfall (about 2130 h local time=GMT+2),
no incandescence was visible anywhere in the summit area except for
a brief glow at the Bocca Nuova, possibly produced by one of its rare
Strombolian explosions.
However, things were to change soon. Mild Strombolian activity began
at about 0300 h on 11 June at the summit vent of the SE Crater and
at the NNE flank vent, and at 0430, lava fountains rose from the latter,
while more intense Strombolian bursts occurred at the summit vent.
As day broke (about 0500 h), a dark tephra-laden eruption column was
seen rising from the summit vent, while fountains jetted about 150
m above the NNE flank vent. Strong tephra emission continued from
the summit vent until about 0600 h and rapidly declined thereafter;
the plume drifted to SW and had reached the Monti Iblei (about 50
km S of Etna) by about 0930 h. Gas emission from the SE Crater continued
through the early afternoon.
Based on the eruptive behavior observed in the past week, it is very
likely that more eruptive episodes will occur at the SE Crater in
the near future, although it is not clear whether the crater will
maintain its surprisingly regular rhythm with eruptive episodes occurring
every 2 days and few hours. In any case, the situation is now very
similar to that during the first months of last year when eruptive
episodes were separated by intervals lasting 6 hours to 10 days.
12 June 2001 update.
The Southeast
Crater has remained inactive after the latest eruptive episode on
the morning of 11 June, with only wisps of gas rising from its summit
vent. This quiet, however, might soon be interrupted by another eruptive
episode, similar to the three events of the past 7 days. At present
(12 June, noon) there are little signs that could help to forecast
if and when another paroxysm will take place, but it is possible that
there will be one within the next 24-48 hours. If not, then the dynamics
of Etna's eruptive activity have once more changed, and it will be
very difficult to say what will happen next. In spite of continuous
sophisticated monitoring, the volcano remains largely mysterious.
Several
other web pages covering the recent and ongoing eruptions of the Southeast
Crater are now available; these contain photos and movie clips of
some of the most spectacular moments of that period.
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)
