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WARNING: Tourism
has resumed on Etna after the end of the recent flank eruption.
Excursions to 2800 m elevation are currently possible from Piano
Provenzana on the northern flank, whereas the access route to the
summit area on the southern flank is interrupted, and the cable car
has been partially damaged. The lava flows and the lowermost
eruptive fissure near the Rifugio Sapienza and the cable car base
station are accessible. |
The latest update is near the bottom of this page
22 July 2001 update.
Etna has
returned to the news big time. On early 17 July, the latest in a series of
violent eruptive episodes at the Southeast Crater heralded what became a
very spectacular, complex and dangerous flank eruption, the first since
the large 1991-1993 flank eruption. At this point it is difficult to
render a complete and accurate idea about the situation, but in the
following paragraphs some of the main outlines of this event will be summarized. The situation is
chaotic; access to the eruption areas (including the summit craters) is
completely blocked except for scientists. Ash is falling over a wide
sector to the SE and S of Etna, including Catania, which received a heavy
shower of fine ash early on 22 July and is now filled with grayish dust.
During the next few days more detail, photos and preliminary maps will be
posted on this page.
Prelude: Eruptive episodes at the Southeast
Crater and strong seismicity. The 13th eruptive episode since
early June occurred on the morning of 7 July with lava fountains and flows
from the "Levantino" and powerful Strombolian explosions at the summit
vent of the SE Crater. After this event, lava emission from the
"Levantino" remained nearly continuous for 10 days, interrupted by an
episode of mild Strombolian activity early on 9 July and a further
paroxysm on the early morning of 13 July, which seems to have been one of
the most violent in the whole series. This event was immediately followed
by one of the most intense earthquake swarms observed at Etna during the
past 20 years. Many of the earthquakes were felt in towns around the
volcano, some even as far as Catania and Acireale. During the following 2
days, more than 2500 tremors were registered, and it became clear that a
flank eruption was imminent. Fears were furthermore aroused when fractures
began to open along the W rim of the Valle del Bove, near the "Belvedere"
lookout. These fractures did not produce any eruptive activity. Seismicity
began to abate on 15 July, but concerns about a flank eruption remained.
17 July 2001: Paroxysm at the Southeast Crater and
first fractures open. Another powerful paroxysmal eruptive episode
occurred at the SE Crater on the early morning of 17 July, and a few hours
later a new eruptive fracture opened at the S base of the SE Crater cone,
in the area of the "Sudestino", a small cone formed in the spring of 2000.
This fracture gradually lengthened downslope and bent south, producing
mild Strombolian activity and a lava flow that extended SSE toward the
Belvedere. On the evening of 17 July a second eruptive fissure became
active to the N of the Montagnola (a large pyroclastic cone formed in
1763, on which the Poseidon's live cam is located) and emitted a major
lava flow that spread out toward the Valle del Bove rim.
18 July
2001: Eruptive fissure opens below the Montagnola. At about 0200 h
(local time=GMT+2) on 18 July, another seismic swarm was accompanied by
the opening of a third eruptive fissure at about 2100 m elevation, located
to the S of the Montagnola, near the eruptive fissure of 1766 (Monti
Calcarazzi). This fissure produced mild Strombolian activity and emitted a
sluggish lava flow that began to advance slowly toward S, in the direction
of the main access road to the S flank of Etna, and threatened a
restaurant. The road was cut later that day when the flow had circled
around the W side of the largest cone of the Monti Silvestri, formed in
1892. During the evening, the activity along this fissure increased
notably, and more lava began to spill southward, heading for the town of
Nicolosi, which lies about 10 km downslope from the eruptive fissure. Also
that evening, a spectator who had ventured close to the eruptive fissure
was injured seriously. While first press reports indicated that the man
was hit by a falling bomb from the erupting vents, it was later revealed
that he had badly fallen when trying to avoid a flying projectile.
19-22 July 2001: New eruptive fissures form, strong explosive
activity. On the late afternoon of 19 July, a new eruptive
vent opened on the N flank of the Montagnola, on the Piano del Lago
at about 2500 m elevation. This vent became the main explosive vent
of the flank eruption and has produced powerful Strombolian explosions
and towering ash columns ever since. During the forenoon of 20 July,
a fifth eruptive fissure became active, this time on the NE flank,
in the Valle del Leone. Lava from this fissure began to flow toward
the Valle del Bove.
Threat to Nicolosi and the cable car area. Many
news reports have described scenes of despair and anxiety in the town of
Nicolosi, as the main lava flow from the fissure at 2100 m elevation is
slowly encroaching toward the town. As of 22 July, the flow front was
about 4 km from the outskirts of the town, but it was advancing very
slowly. Presently it appears not very likely that the flow will invade the
town unless the eruption parameters change significantly, but some
isolated structures such as restaurants, weekend homes and roads are at
risk. The lava flow that issues from the fissure at 2700 m elevation
presents a serious threat to the tourist complex around the Rifugio
Sapienza and the cable car, which had been destroyed already twice during
flank eruptions in 1971 and 1983. Bulldozers have created earth barriers
to contain or divert this flow, which in its upper course has already
damaged a ski lift. Some damage has also been caused by falling bombs
ejected by the explosive vent near the Montagnola; it is not clear whether
the Poseidon live-cam is still intact. No images have been transmitted
from this camera since several days, but two new live-cams are
transmitting continuous streaming video (!!!), one is posted close to the
eruptive fissure at 2100 m elevation, the other at Nicolosi. You can
access both at Videobank.it.
More far-reaching
effects are caused by the continuous rain of fine ash caused by the
explosive activity at the vent near the Montagnola. The entire area
between Giarre and Catania lies under a thin sheet of gray dust; there is
a large amount of ash in the city of Catania itself. During the early
morning and forenoon of 22 July, a heavy shower of ash fell over Catania,
forcing the closure of the international airport of Fontanarossa for three
hours.
23 July 2001 (morning) update.
The flank
eruption continues in full force this morning, a towering ash column is
rising from the explosive vent at about 2600 m elevation and is drifting southward, directly
over Catania this morning. causing a continuous rain of fine ash and
blotting out the sun. As the two main lava flows from the fissures at 2700
and 2100 m elevation on the southern flank are advancing, efforts to slow
or alter the movement of these flows are being carried out. The earlier of
these flows presents a serious threat to the cable car station and nearby
touristic structures such as the Rifugio Sapienza, while the latter is
presently advancing very slowly on nearly flat terrain about 4 km from the
outskirts of the town of Nicolosi. In contrast to the news reports
spreading around the globe about scenes of panic and terror in Nicolosi,
the population of that town is essentially relaxed, as could be
ascertained during a visit on the evening of 22 July. To most of the
people there it's nothing else than a really BIG ETNA PARTY.
The
eruptive fissure at 2100 m elevation was visited by Behncke and others on
the evening of 22 July, with eruptive activity in full swing and a broad
lava flow issuing from the lower part of the fissure. Scenes of despair
were witnessed at the cable car station which appeared doomed when a minor
lava lobe fed by the vents at 2700 m elevation (to the N of the
Montagnola) rapidly spilled down the steep slope above these structures.
Hasty attempts were undertaken to construct earth barriers in order to
halt or divert the various active flow lobes menacing the area below, but
each barrier was soon overrun by the lava. However, so far all lobes have
stopped several hundred meters from the cable car station and Rifugio
Sapienza, and by 0200 h on 23 July (local time=GMT+2) lava production from
the vents at 2700 m elevation appeared slightly reduced.
The activity
of the explosive vent on the N side of the Montagnola, at about 2600 m
elevation, was majestic, with dense volutes of dark gray ash rising
hundreds of meters, punctuated by spectacular bursts of incandescent bombs
that rose up to 200 m high. This vent has been described by various
observers as a huge pit that is slowly eating into the side of the
Montagnola. Ejecta from this vent have reached the area where the live-cam
of the Istituto Nazionale di Geofisica e Vulcanologia (formerly Poseidon)
is located, and one of the small wooden shacks located there has been
observed burning, but no one really knows at this time if the one
containing the live-cam is still intact.
The protagonist of the show is
without any doubt the eruptive fissure at 2100 m elevation. This fissure
is located about 200-300 m uphill from the largest of the Monti Silvestri
craters (formed during an eruption in 1892) and has five explosive vents
that erupt continuously, while at least two further vents lying higher
upslope are erupting sporadically and frequently emit ash. One vent in the
upper part of this fissure is particularly active, with continuous
Strombolian bursts 50-70 m high; a pyroclastic cone is rapidly growing
around this vent, which by midnight on 23 July was about 30 m high and
open toward south. A broad lava flow issues from the lower part of the
fissure, turning around the W side of the main Monti Silvestri crater and
continues southward from there, across the Provincial Road 92 (which
connects the Rifugio Sapienza area with the town of Zafferana) and down to
about 1000 m elevation, more than 6 km from its source. This flow is
moving as a single, broad sheet, without any flow channels or lava tubes
forming, and this renders the situation more difficult because the
possibilites to alter the course of the flow are very limited. So far, it
has been tried to slow the advance of the flow by dropping large amounts
of water on it from airplanes usually engaged in fighting forest fires.
However, this lava
flow, which, according to national and
international mass media, is seriously threatening the town of Nicolosi,
is advancing very slowly, mostly because it has reached a nearly flat area
about 4 km north of the town. At the present effusion rate (which is
estimated at 20 cubic meters per second for the eruptive fissure at 2100 m
alone; the combined effusion rates of all four effusively active fissures
are near 30 cubic meters per second), the flow is expected to advance only
slowly. This might change once the flow becomes channelized or develops a
lava tube; this could bring the flow front much further downslope, as has
happened during the previous flank eruption, in 1991-1993.
Much has
been said and written in the news media about the attitude of the people
of Nicolosi toward the menace from the lava flow. Reports went as far as
describing scenes of despair and panic, and told of residents packing
their things together to leave their doomed homes. Of this NOTHING is true. The state of affairs at Nicolosi as observed on the evening of 22
July was the following: the residents of the town are all outside to watch
the towering ash column and the glowing vents and lava flows, but to many
it's rather a spectacular display, a grand show, a big party. In the
evening, thousands of people were walking up the access roads (blocked to
car traffic) to obtain a view as close as possible of the eruption. At
about 2030 h, a procession was held in the center of the town in order to
pray for a good outcome, but this was not the dramatic, desperate event as
announced by the media, it was rather a chance for everyone to show their
new clothes and meet friends and relatives. The procession did not go
outside the town toward the lava flow, but circled once around the main
square of the town and then returned into the church.
In Catania, twice
as distant from Etna as Nicolosi, the atmosphere is more eery. On the
morning of 23 July, the ash plume from the explosive vent at 2600 m
elevation is drifting right over the city, dropping fine, dark gray ash
onto everything. Dust is in the air and enters everywhere, especially into
one's eyes. A thin layer of ash covers cars, houses, trees, roads, and
more is falling in every moment. The dense plume overhead, Catania does
not see the sun this morning although the weather is clear. This plume is
well visible in the latest Meteosat images which are displayed on the DSRS web site. On the
forenoon of 23 July the Fontanarossa International Airport of Catania had
to be closed for the second time since 22 July due to the falling ash.
The current flank eruption might continue for weeks or even months
to come. Etna has accumulated an enormous amount of magma since it began
re-inflating after the 1991-1993 flank eruption, so no one expects this
new one to end soon. Seismic activity is continuing, with felt seismicity
occurring once more on 22 July. It cannot be excluded that still more
eruptive fractures will open, maybe even at lower elevation, and this
would render the situation far more serious. Yet it is already a HUGE
flank eruption, with up to 10 million cubic meters of lava emitted so far.
To those living nearby it's a grand show, a bit of a thriller, and to the
volcanologists working at Etna it's an enormous amount of work. For this
reason updating on this page will depend much on when there will be a bit
of free time between visits to the theater of the eruption and interviews
with (mostly German) television and radio stations and newspapers. To have
a taste, German visitors may read an interview given to the journal "Welt am
Sonntag" on 22 July.
24 July 2001 (morning)
update.
Today's update
is very brief due to extreme work overload. The flank eruption is
continuing at full speed, although the main lava flow directed toward
Nicolosi has almost stopped moving. On the afternoon of 23 July, the S
flank of the SE Crater cone split open, emitting a lava flow toward the
Valle del Bove, and during the following night, lava also began to issue
from the "Levantino" vent on the NNE flank of the same cone, emitting lava
toward the Valle del Bove as well. This indicates that the level of magma
within the central conduit system has not sunken at all in spite of the
continued emission of lava from vents much lower on the flanks of the
volcano.
29 July 2001 (morning) update.
Due to
problems with my computer it has been impossible to update this page
for the past few days; furthermore the eruption is giving us a tremendous
amount of work, so that this update is only brief.
The flank eruption initiated on 17 July is continuing vigorously;
four eruptive fissure systems on the southern flank and one on the
northeastern flank remain active. The lava flow which issued from
the lowermost fissure at about 2100 m elevation on the S flank stopped
advancing on 24 July, but since 28 July a new flow lobe is advancing
on top of the earlier one, reaching almost the same extent (about
4 km from its source). This new flow is advancing slowly and does
not presently present a significant threat to the town of Nicolosi.
The eruptive vents at 2100 m elevation showed decreasing activity
until 26 July but reintensified after that day, and on the evening
of 28 July, Strombolian activity was as vigorous as during the first
days of the eruption.
The eruptive vents at 2500 m elevation (in the Piano del Lago, immediately
to the N of the Montagnola) have shown a significant change in their
activity. During the first week of the eruption, activity there was
purely explosive and had a phreatomagmatic character, possibly caused
by a shallow acquifer, which was largely consumed by 25 July, and
during the early morning of that day the activity became mostly magmatic.
Violent Strombolian explosions were visible at that cluster of vents
on 25 July, and later that day lava began to issue from one of the
Piano del Lago vents. During the following days a large pyroclastic
cone began to grow around three of the vents, which is informally
named "Montagnola 2" or "Monte del Lago"; on the evening of 28 July
this cone was about 50 m high.
When observed from about 300 m distance on the afternoon and evening
of 28 July, the "Monte del Lago" showed very intense explosive activity,
mostly from a large vent at its summit, but phreatomagmatic explosions
occurred intermittently from vents on its NW and S flanks. Very powerful
explosions at the summit of this cone were accompanied by flashing
arcs, atmospheric shock waves that caused pain to the ears and rattled
windows as far as in Catania, and extremely loud detonations. At times
the entire cone was covered with meter-sized incandescent bombs. At
other times water apparently gained access to the vents, and the activity
became distinctly phreatomagmatic, with increased ash emission and
characterized by the almost complete absence of eruption sounds. During
the strongest magmatic explosions bombs were thrown 500 m or higher
above the vent. A second vent, lying closer to the Montagnola, produced
extremely violent explosions every 5-30 minutes.
Lava from one of the "Monte del Lago" vents began to spill down along
the cable car track on 26 July and rapidly reached the tourist complex
around the Rifugio Sapienza where it overwhelmed a building of the
Provincial Tourist Agency and buried another section of the road connecting
the Rifugio Sapienza area with Zafferana (a section further to the
E had been buried during the second day of the flank eruption by lava
from the vents at 2100 m elevation). Efforts to divert this lava flow
proved partially successful, for the lower cable car station and the
Rifugio Sapienza were saved. However, the upper cable car station
was partially surrounded by a lobe of lava, and several poles of the
cable car were damaged. On 28 July lava emission from the "Monte del
Lago" in the direction of the tourist complex had diminished notably,
giving rescue workers a moment of relief. However, new eruptive vents
opened on 27 July near the "Monte del Lago", closer to the Montagnola,
and a new lava flow began to run toward the S part of the Valle del
Bove, covering a part of the Canale della Montagnola, a popular excursion
route.
Lava continued to flow, at a reduced rate, from the fissure at 2700
m elevation, where a small pyroclastic cone had formed early in the
eruption; this lava took a southwesterly route without posing any
threat to buildings or other structures. During the preceding days
lava from these vents had completely buried what remained of the "Piccolo
Rifugio" and the nearby hornitos of the 1985 eruption.
Vigorous eruptive activity continued as of late 28 July at the uppermost
fissure, close to the "Sudestino" on the SE base of the SE Crater
cone. Activity there was observed at very close range on 26 July,
when Strombolian explosions occurred at 5-6 vents (which had built
a cluster of large hornitos), often with large magma bubbles bursting
spectacularly. Lava issued from a vent about 200 m downslope from
the hornitos and ran toward the Valle del Bove; the flow front had
almost reached the bottom of that depression. Intermittent effusive
activity was also observed at the Levantino between 24 and 26 July.
The Valle del Leone vents on the NE flank showed only modest activity
on 26 July; a single hornito had formed there but did not produce
any explosive activity. Lava from this fissure flowed along the base
of the N rim of the Valle del Bove and extended as far as Monte Simone,
a cinder cone formed in the early 19th century. During the following
days the activity at this fissure showed a further decrease.
30
July 2001 update (thanks to ONCEOM S.p.A., Catania, for giving me
access to their computers and rendering this update possible).
The flank
eruption initiated 13 days ago is continuing vigorously and shows
no signs of ending soon. On the evening of 29 July, eruptive activity
was still occurring at five eruptive fissures, one on the NE flank
(in the Valle del Leone) and four on the S flank (2950, 2700, 2500
and 2100 m elevation). The strongest activity is taking place at a
cluster of vents at 2500 m elevation, where a huge pyroclastic cone
is rapidly growing. This cone, informally named "Monte del Lago"
has reportedly grown 100 m high as of 30 July and continues to produce
very strong explosive activity. Detonations are audible as far as
Catania, even during the hours of intense traffic, with atmospheric
shock waves that rattle doors and windows. Lava from a nearby vent
formed on 28 July is now flowing along the "Canalone della Montagnola"
into the southern part of the Valle del Bove, whereas another flow,
which a few days ago has damaged the cable car on the W side of the
Montagnola, has lost vigor and does not present a significant threat
at this moment.
Vigorous eruptive activity is also continuing at the eruptive fissure
at 2100 m elevation, and lava continues to issue from the lowermost
vents on this fissure in the direction of Nicolosi, without, however,
posing a significant threat to that town. Lava emission and mild explosive
activity are continuing as well at the two fissures at 2950 m (near
the SE Crater) and 2700 m elevation. The eruptive fissure in the Valle
del Leone was still mildly active late on 29 July, but the lava flow
emitted there was stagnant, having extended to near Monte Simone in
the N part of the Valle del Bove.
Near continuous ash falls on the S flank of the volcano, including
Catania, are causing distress, and the international airport Fontanarossa
of Catania had to be closed repeatedly on 29 and 30 July, forcing
thousands of tourists to wait for their flights and to be transferred
to other airports such as Palermo and Reggio Calabria. Besides this,
the eruption is causing little problems for those living near the
volcano. No inhabited areas are presently at serious risk, and the
widespread news about an atmosphere of anxiety and panic are completely
wrong. Neither is there any truth in reports that said the eruption
had temporarily halted (this was reported sometime last week). The
eruption has never ceased, but there have been some minor fluctuations,
and the character of activity has changed significantly at the "Monte
del Lago" between 24 and 25 July. There has been serious debate
between the Director of the Italian Civil Protection, Franco Barberi,
and the Director of the National Institute for Geophysics and Volcanology,
Enzo Boschi, which has occupied large space in the local and international
news. Essentially, on 25 July, Barberi declared that the level of
magma within the central conduit system of Etna had lowered, and thus
the danger was over; furthermore Barberi said that all lavas emitted
from the various eruptive fissures were all of the same composition.
Boschi then repeated that nothing of all this was true and accused
Barberi of downplaying the risk of the eruption.
What is true indeed is that the magma level has not lowered at all;
the vents erupting at 2950 m elevation are splendid evidence of magma
standing still very high in the central conduit system. Then, it is
one of the most amazing facts of this eruption that different types
of lava are being emitted from the various eruptive fissures. Those
issuing from the vents at 2100 m elevation contain large phenocrysts
of pyroxene and plagioclase, and there are also numerous inclusions
(up to 5 cm across) of sedimentary and metamorphic rocks derived from
the strata underlying the volcanic edifice. The presence of these
phenocrysts and xenoliths (non-volcanic inclusions) will likely provide
precious information about the area where magma has been stored prior
to the current eruption. On the other hand, lavas emitted at 2950
m elevation are clearly different in that they contain only very small
pyroxene and plagioclase phenocrysts and no xenoliths at all, indicating
that this magma has risen rapidly from a much deeper source area,
without resting temporarily below the base of the volcanich edifice.
This eruption thus is a case of summit and flank activity occurring
simultaneously; the vents at 2100 m elevation are not draining the
central conduit system. While geologists are busy observing the ongoing
activity, a vigorous flow of data is arriving from Etna, which will
be ready for study and interpretation once this eruption ends, and
it can already be said that this will be the best studied eruption
ever at Etna. It is likely that we will learn more about this volcano
in this one eruption than has been learned about Etna in the preceding
3000 years of historically documented activity.
For more information, live cams, and a very good FAQ, visit the Etna
2001 page at Videobank. And, good to find this, there is also
a page dedicated to Etna available at the INGV
(Istituto Nazionale di Geofisica e Vulcanologia) web site, which
has very frequent updates (in Italian), photos, and maps.
15
August 2001 update (thanks to the owners of the Hotel
Corsaro on the southern flank of Etna, for giving me
access to their computers and making this update possible). The flank
eruption initiated on 17 July ended sometime on late 9 or early 10
August. During the preceding days the activity had shown a distinctly
decreasing trend, the eruptive fissures becoming inactive one after
another. Preliminary estimates indicate that about 50 million
cubic meters of lava and pyroclastics were emitted during 25 days of
activity, which makes this a relatively modest eruption, and it seems
that much magma has remained stored below the volcano, ready for the
next flank eruption.
Strong explosive activity continued at the new large cone "Monte
del Lago" (at 2500 m elevation) until 1 August, after which it
changed to vigorous ash emission with occasional bursts of bombs; on 3
August ash emission from this cone was intermittent and ended during
the following days. Mild explosive and effusive activity continued at
the spatter cones at 2950 m elevation through at least 2 August; while
the vents at 2700 m elevation emitted lava through 7 August. At the
fissure at 2100 m elevation, Strombolian activity was vigorous until
about 2 August and then declined rapidly; lava continued to flow from
the lowermost vent on this fissure through late 9 or early 10 August.
After 1 August, when lava flows from a vent at 2500 m elevation had
burned the upper cable car station, covered another portion of the main
access road and seriously threatened structures of the tourist complex
around the lower cable car station, there have been no further
dramatic developments. The cable car has been partially destroyed and
the dirt road that leads to the summit area on the S flank has been
interrupted by lava flows. Access to the summit area from S will be
impossible for at least several months to come. On the other hand, the
eruption has never presented a serious threat to the town of Nicolosi.
The most widespread effects of this eruption were the heavy ash falls,
especially in the direction of Catania and Acireale, forcing repeated
closures of the international airport of Catania.
The end of this eruption, which for many reasons was one of the most
unusual and spectacular flank eruptions of Etna during the past few
centuries, came surprisingly soon. Many scientists studying and
monitoring Etna had expected it to go on for many weeks if not months.
Most likely eruptive activity will resume at the summit craters
relatively soon - maybe within a few months - and this will be the
prelude to another flank eruption.
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, extremely up to date
(mostly in French)
