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Note:
this report contains a few photographs taken from press and other internet
sources at the time of the eruption. New photographs taken by myself
after the eruption are available in a series of photo
galleries, documenting the changes generated by the 2002-2003 eruption
and showing the eruptive sites. Some of the photos
that I took during the eruption plus a few taken by Giuseppe Scarpinati
are available as well. See also "Piano
Provenzana - a requiem"
Immediately
before midnight 26 October (local time=GMT+1), a new flank eruption
began at Etna after only few hours of premonitory seismicity. This eruption
was more violent and more devastating than the previous flank eruption
in July-August 2001 and once more occurred
from fissures on two sides of the volcano: at about 2750 m on the southern
flank, and at elevations between 2500 and 1850 m on the northeastern
flank, in an area known as the Northeast Rift. After its extremely vigorous
start, the eruption showed a declining trend through 5 November (on
that day all activity on the Northeast Rift ended) and then continued
in a more or less stable manner on the upper southern flank. Most of
the early lava (about 10-11 million cubic meters as of 12 November)
was disgorged from the NE rift vents, while activity on the southern
flank was highly explosive and generated lava flows on two occasions:
between 28 and 30 October and again starting on 13 November. The eruption
ended after three months and two days, on late 28 January 2003. Lavas
erupted between 13 November 2002 and 28 January 2003 on the southern
flank amount to about 20 million cubic meters. The volume of pyroclastics,
of which a large portion fell as ash over wide areas around the volcano,
is considerably larger than that of lava (40-50 million cubic meters),
which is unique in the recent history of Etna's flank eruptions.
The tourist complex and skiing areas of Piano Provenzana were nearly
completely devastated by the lava flows that issued from the NE Rift
vents on the first day of the eruption. Heavy tephra falls caused by
the activity on the southern flank occurred mostly in areas to the south
of the volcano and nearly paralyzed public life in Catania and nearby
towns. For more than two weeks the International Airport of Catania,
Fontanarossa, had to be closed due to ash on the runways. Strong seismicity
and ground deformation accompanied the eruption; a particularly strong
shock (magnitude 4.4) on 29 October destroyed and damaged numerous buildings
on the lower southeastern flank, in the area of Santa Venerina. Lava
flows from the southern flank vents seriously threatened the tourist
facilities around the Rifugio Sapienza between 23 and 25 November, and
a few days later destroyed a section of forest on the southwestern flank.
In mid-December, lava flows again threatened the Rifugio Sapienza area
and two buildings were destroyed. In late December, the site of the
former arrival station of the cable-car at 2500 m elevation was covered
with new lava.
The eruption brought a heightened awareness of volcanic and seismic
hazards to the Sicilian public, especially because it occurred only
one year and three months after the previous eruption that was strongly
featured in the information media. At the same time it showed the weak
points in emergency preparation and volcano surveillance in general.
While the eruptive and geophysial phenomena provide an enormous amount
of new and fascinating data, the timing and location of the eruption
were virtually unpredictable until a few hours before the opening of
the first vents. An understanding of the volcano and its activity thus
cannot be based on instrumental monitoring alone.
The following is a summary of the events since the end of the 2001 eruption
and a preliminary analysis of the significance of this eruption in the
framework of Etna's recent activity. Please note that some of the information
is preliminary and thus subject to possible change.
Map
of the lava flows of October 2002 to January 2003
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The
definitive map of the lava flows emitted during the 2002-2003
eruption (shown in red), based in part on post-eruption surveys
of the lava fields (much of these carried out by staff of the
Catania section of the Istituto
Nazionale di Geofisica e Vulcanologia). Pyroclastic cones
are shown in dark brown color, and eruptive vents in yellow. Lavas
erupted during the July-August 2001 eruption are shown in pink
for comparison; however, the longest and most voluminous flow
of that eruption is not shown in full extent |
Prelude.
Was there a prelude to the 2002-2003 eruption of Etna? Compared to the
vigorous and spectacular summit eruptions
that had preceded the 2001 eruption, the 2002-2003 eruption had very
few precursors, and in any case these did not permit to foresee or predict
the event. First, there was a relatively brief period of mild summit
activity, which started in mid-June with explosions at the Bocca Nuova,
and soon after the activity extended to the Northeast Crater. Between
early July and mid-September the Northeast Crater was the site of Strombolian
activity which led to a rapid shallowing of its central pit, and at
times bombs fell onto the outer flanks of the Northeast Crater cone.
On 22 September, a magnitude 3.6 earthquake occurred on the northeastern
flank of Etna, in an area known as Piano Pernicana. This event was accompanied
by extensive ground fracturing, which was especially notable on the
"Mareneve" road, which connected the town of Linguaglossa
and Piano Provenzana. The ground fracturing was related to displacement
along the Pernicana Fault System, which is well known and was the site
of several similar episodes during the 1980s. At the time the event
was not interpreted as being directly related to the eruptive activity
of the volcano, but a few days later, all activity at the summit craters
ceased, except for a few minor phreatomagmatic explosions at the Northeast
Crater. In hindsight, it might be speculated that the earthquake signalled
the opening of the Northeast Rift, and magma drained from the central
conduit system into the flank of the volcano, causing the abrupt cessation
of the summit activity.
For the following weeks the summit craters showed no activity except
quiet degassing. Mountain guides who visited the craters on Saturday
26 October noted nothing unusual, but late on that day magma began to
move within the volcano.
Precursory seismicity.
An intense earthquake swarm at shallow depth within the volcano began
at approximately 2125 h (local time=GMT+1; note that the eruption beginning
coincided with the return from the Middle European Summer Time to the
normal Middle European Time), and this was the first clear indicator
of the impending eruption. A group of hikers staying at the Hotel "Le
Betulle" at Piano Provenzana, at about 1800 m elevation on the
northeastern flank of Etna, was awakened by the tremors and had to abandon
the building which was seriously damaged by the seismicity. The seismic
activity was caused by the rapid uprise of magma and associated fracturing
of the flanks of the volcano. At dawn on 27 October those who still
remained at Piano Provenzana noted that large E-W trending fractures
had cut through the pavement of the parking lot of the tourist complex.
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This
is what remains of the restaurant "La Provenzana" after
the strong earthquakes that shook the Piano Provenzana area immediately
before and during the opening of the first vents on the Northeast
Rift on 27 October 2002. All other structures of the tourist complex
of Piano Provenzana were buried by lava flows on the first day
of the eruption. Photo is from the 2 November 2002 issue of "La
Sicilia" |
Eruption
begins. The first eruptive vents to become active during
this eruption opened at 2345 h on 26 October, on the upper southern
flank and immediately began to produce intense explosive activity. A
fissure about 1 km long formed between 2850 and 2600 m; its lower end
lay next to an abandoned older arrival station of the cable-car (this
had been partially destroyed by the 1983 eruption), which had been used
as a shelter by numerous excursion groups. This fissure lay about 1
km to the northwest of the largest cone formed during the 2001 eruption
(which a few weeks earlier had been officially named "Monte Josemaria
Escrivà"). The activity was accompanied by loud detonations
and led to the rapid growth of a large pyroclastic column, which was
driven by the wind to the south.
At approximately 0230 h a few persons watching the summit of Etna noted
the sudden onset of high lava fountaining from the northern base of
the Northeast Crater, which lasted only a few minutes. Only a few hours
later, a second eruptive fissure became active in the central portion
of the Northeast Rift (starting from about 2500 m downslope), in the
area of a fissure that was active in 1809. Eyewitnesses who stayed at
Piano Provenzana, only about 1.5 km downslope, stated that the opening
of each new vent was accompanied by strong seismicity, which destroyed
or damaged most of the structures at the tourist complex, and intense
ground fracturing. Lava began to issue from the new vents and to spill
down the slope above Piano Provenzana, destroying part of the ski lifts
in the area. The fissure gradually propagated downslope, generating
more lava flows that came closer and closer to the buildings at Piano
Provenzana.
At dawn on 27 October, an enormous black cloud rose several kilometers
above the vents on the upper southern flank, while smaller ash columns
rose from the vents on the Northeast Rift. The plume was driven southward
over the densely populated areas around Catania, causing heavy ash falls
that were to paralyze public life and traffic for several days. The
eruption was well visible even at great distance, such as the Aeolian
Islands, more than 100 km to the north. For many hours the summit area
of the volcano was completely veiled by the ash clouds, and it was difficult
to obtain a clear idea of what was happening in the eruption area.
At noon on the same day, the first lava flow began to invade Piano Provenzana,
and by the evening of that day, the once verdant plain with its touristic
structures had been virtually obliterated by the lava. Only one building,
a restaurant named "La Provenzana", remained standing, but
it had been seriously damaged by the earlier earthquakes. During the
following days incandescent bombs from the nearest eruptive vents set
the damaged building ablaze and thus completed the work of destruction.
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Vigorous
lava fountaining characterized the activity along the new eruptive
fissures on the Northeast Rift during the first days of the eruption.
On 28 October, the main portion of the fissure system had no less
than 15 eruptive vents producing lava fountains, and it was from
these vents that the lava flows issued which destroyed Piano Provenzana.
Photograph was published in the 28 October 2002 issue of the newspaper
"La Sicilia" |
Eruption
progress, earthquakes and displacements. By the afternoon
of 27 October, the main lava flow which had buried Piano Provenzana
was rapidly advancing across the beautiful pine forest of Linguaglossa
(locally known as "Ragabo", a word derived from the Arabian,
which means "great forest"). Portions of the forest were set
ablaze and helicopters and canadair were busy in dousing the fires.
At the fissure on the southern flank, the activity was purely explosive
(that is, no lava was emitted from these vents), and the immediate surroundings
of the fissure were buried under a thick blanket of pyroclastics, transforming
much of the 2001 lava flows into a gray desert of scoriae and ash.
During the night of 27-28 October, the fissure on the Northeast Rift
propagated further downslope to an elevation of approximately 1890 m,
and new lava flows began to advance along the lower portion of the rift,
passing on the eastern side of the large cone of Monte Nero (formed
during an eruption in 1646-1647). An uninhabited mountain hut (Rifugio
Monte Nero) was buried by this lava. At the same time, lava flowed for
the first time from the lowermost vent on the southern flank and formed
a flow that advanced southwestward. This flow did not come near to the
tourist complex around the Rifugio Sapienza, which had been seriously
threatened by the 2001 eruption.
On 28 October it became clear that the eruption onset had been accompanied
by significant displacements along the Pernicana Fault System on the
northeastern flank of Etna. The "Mareneve" road had been fractured
in numerous places, and displacements were observed in an area lying
between the lower portion of the Northeast Rift to the west and the
village of Vena to the east. Evidently a portion of the eastern flank
of the volcano had moved sideward, toward the sea. Ongoing movement
was indicated by the continuing seismic activity, with hundreds of minor
earthquakes distributed in several areas on the northeastern and eastern
flanks. During the forenoon of 29 October, these earthquakes became
stronger and more frequent and culminated in a magnitude 4.4 event,
whose epicenter lay near the village of Santa Venerina on the lower
southeastern flank of Etna. Numerous buildings in a portion of the village
were damaged or destroyed, and more than 1000 people left homeless;
fortunately there were no reports of serious injuries among the population.
The earthquakes dramatically increased the nervosism prevailing in the
area since the beginning of the eruption. Two days later, a magnitude
5.4 earthquake occurred several hundred kilometers to the north, in
the region of Molise (central-southern Italy), destroying buildings
and causing 29 fatalities; this event was not related to the geodynamic
activity at Etna.
During the first days of the eruption, three of the four summit craters
were active as well. The Northeast Crater showed intermittent Strombolian
activity, indiating that magma was still at high levels in the central
conduit system, and ash was emitted periodically from the Bocca Nuova
and the Voragine. The Southeast Crater, which had actively participated
in the 2001 eruption (and the prelude to that eruption) was entirely
quiet.
Eruption
ends at NE Rift. On the third day of the eruption, a
distinct decrease of the intensity of the activity was evident. The
lava flows emitted from the Northeast Rift vents slowed; the longest
of these had reached a length of about 5.5 km and was still far from
the nearest town (Linguaglossa). A decrease in the effusion rate was
also noted at the fissure on the southern flank, but lava fountaining
accompanied by voluminous tephra generation continued, and ash continued
to fall onto Catania and neighboring areas, forcing the continued closure
of the Fontanarossa International Airport.
During the following days the eruptive activity continued at a consistently
decreasing trend. On the evening of 1 November the main lava flow on
the northeastern flank advanced at a speed of less than 1 m per hour
and 24 hours later it was nearly stagnant. Explosive activity at the
vents on the Northeast Rift decreased likewise. On 3 November, only
a very small portion of the lava flow near the eruptive vents was active;
on the southern flank all effusive activity had already ceased by 1
November. The only site of continued vigorous eruptive activity was
the largest of the new vents on the southern flank, where a large cone
had grown. When observed on the evening of 3 November, this cone had
more or less the same dimensions of its one-year-old neighbor, Monte
Josemaria Escrivà, being about 100 m high. By 5 November, all
activity on the Northeast Rift had ended, but explosive activity continued
on the southern flank for the next week without significant signs of
weakening.
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Strombolian
activity and emission of a small lava flow at the large pyroclastic
cone on the upper southern flank on late 13 November 2002. Volcanologists
and technicians of the Civil Protection are visible in the foreground.
Photo was published in the 14 November 2002 issue of "La Sicilia" |
Surprises
on the southern flank. Activity on the southern flank
entered into its third week with near-continuous ash emissions, and
ash became the obsession of the people living around the volcano,
especially in the Catania area which had received most of the distal
fallout and suffered serious economic damage from the continued closure
of the Fontanarossa International Airport of Catania and a dramatic
decline in tourism. On the afternoon of 13 November the ash plume over
Etna suddenly disappeared, as the activity changed to "clean",
ash-free Strombolian explosions. This was due to a sudden rise of the
magma column in the conduit, and soon after lava began to issue from
a small fissure on the southern base of the new pyroclastic cone (named
2750 cone hereafter). During the following days Strombolian activity
alternated with ash emissions at the main vent, but lava continued to
issue from the new fissure and covered a portion of the lavas emitted
from the same area in late October. On 19 November, the new lava flows
had extended far beyond the October flows to a length of about 4 km
and threatened the Botanical Garden of Etna. A new lava flow issued
from a vent on the southeastern flank of the 2750 cone on 21 November,
and for the next four days repeated surges of lava advanced ever closer
to the Rifugio Sapienza and nearby buildings. Since early 25 November,
lava again flowed southwestward, in the direction of the Botanical Garden,
and explosive activity shifted from the summit of the 2750 cone to new
vents on its sides. In early December lava emission ceased, while explosive
activity was concentrated at a vent at 2800 m elevation, on the northern
side of the 2750 cone. A second cone rapidly built around the 2800 m
vent (wherefore it is hereafter named 2800 cone), overtopping the 2750
cone within a few days. The nearby "Torre del Filosofo" mountain
hut, for many years a symbol of "civilization" (in both a
positive and negative sense) close to Etna's summit craters, gradually
vanished under the tephra ejected by that vent; on 10 December it was
reported that only the antennas posted on the roof of the building were
still protruding from the cover of pyroclastics.
10 December brought yet another change as explosive activity returned
to the 2750 cone, and lava began once more to isse from its southeastern
base, forming several flows. The most vigorous of these began to advance
southward, again in the direction of the Rifugio Sapienza area. Between
15 and 17 December this flow crossed the Provincial Road 92 that connects
the Rifugio Sapienza area to Zafferana; a small side lobe destroyed
a building of the Provincial Tourism Agency and somehow was involved
in a powerful explosion that injured 32 people and caused a fire in
the nearby restaurant "Esagonal" on early 16 December.
From then on the eruption showed a gradual, though irregular decline.
Lava flows again changed direction and advanced southwest; when a new
shift toward south occurred in January 2003, the effusion rate had already
dropped and the new flows did not extend as far as earlier in the eruption.
Explosive activity became intermittent in January, sometimes generating
light ash falls, but it seemed that the most critical phase of the eruption
was over. All activity ended on the evening of 28 January, and the eruption
was over, having lasted 95 days.
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Aerial
view of the eruption area on the southern flank of Etna, 10 December
2002, looking northeast. Mild explosive activity from several
vents within the large crater of the 2800 cone is seen at left,
and a dense ash plume is emitted from the 2750 cone in the center
of the photographs. White gas plumes mark the path of lava flows
issuing from the southeastern base of the 2750 cone at right.
A part of the prehistoric cone Monte Frumento Supino (covered
with snow) is visible in lower left corner. Photo is from the
web site of "La Sicilia" |
Volcanological
features. The 2002-2003 eruption has been described
in many reports as a highly unusual event for Etna, and it seems that
this is true. Firstly, this is one of the most explosive eruptions of
this volcano in recent times. More than two-thirds of the total volume
of erupted products is pyroclastics, contrasting with most recent eruptions
of Etna which produced mainly (or nearly exclusively) lava. In a 12
November report in the local newspaper "La Sicilia", volcanologists
of the Istituto Nazionale di Geofisica (Catania section) were cited
to have estimated the volume of lava emitted to that day at 10-11 million
cubic meters, while the volume of tephra exceeded 20 million cubic meters.
The intermittent effusive activity since 13 November on the southern
flank is likely to have doubled the lava volume, and the tephra volume
may have grown in a similar manner during the month after 12 November.
Secondly, the 2002-2003 eruption was actually two-eruptions-in-one,
with two different types of magma being erupted on the southern and
northeastern flanks. The fissures on the Northeast Rift produced the
"common" Etna magma that has been produced by all eruptions
in the past few centuries, while the vents on the southern flank produced
a magma rich in amphibole, a water-bearing mineral that has been relatively
rare in recent products of Etna until the 2001 eruption. (It seems,
though, that similar amounts of amphibole were contained in relatively
recent magmas such as that of 1892, at the Monti Silvestri, and 1763,
at the Montagnola, both located on the southern flank.) In this sense
the 2002-2003 eruption is a repetition of the events of July-August
2001, when the same two magma types were erupted simultaneously from
the different systems of eruptive fissures. It is assumed by some researchers
that in both events the uprise of the "new" magma below the
southern flank caused extensive fracturing of the volcano, triggering
the lateral draining of magma from the central conduit system at the
same time when the "new" magma arrived at the surface. In
this scenario the activity on the Northeast Rift and the destruction
of Piano Provenzana are merely the "side effects" of the uprise
of the "new" magma, which otherwise might not have occurred.
Thirdly, the invasion of Piano Provenzana and the "Ragabo"
forest by lava flows marks the end of a long, quiet period in that area;
no lava flows had occurred in these places in historic time. The most
recent major eruption on the Northeast Rift, in 1923, had occurred a
few hundred meters further west on the rift, so that the lava flows
traveled along-rift, in the direction of Linguaglossa, while in 2002
most of the lava took a more easterly course.
Last but not least, the intense ground fracturing and seismicity which
preceded and accompanied the first days of the eruption yields fascinating
insights into the dynamics of this volcano and its geodynamic environment.
While a relationship of the eruption, seismicity and ground fracturing
with the earthquakes in Palermo (6 September 2002) and Molise (31 October
2002) can be excluded, all geodynamic phenomena in the Etna area are
most likely closely correlated. Yet the character of these correlations
are subject to discussion among scientists working on Etna. Concerning
the seismic and eruptive events at the volcano itself, it appears that
there is a striking correlation between large-scale flank slip and magma
uprise. In fact, on 22 September, the eastern flank of the volcano began
to slip toward the Ionian Sea, with movement occurring mainly at the
Pernicana Fault System (Neri et al. 2003). This probably allowed magma
to migrate from the central conduit system into the Northeast Rift,
although a second, larger flank slip event was necessary to permit magma
uprise to the surface - and not only on the Northeast Rift, but also
on the southern flank, where the magma came from the eccentric reservoir
already active in 2001. The eruption can thus be interpreted as having
been triggered by the enormous flank slip, in contrast with the 2001
eruption, which was preceded by the forceful uprise of a dike from the
eccentric reservoir, and possibly was triggered by regional tectonic
compression (Acocella et al. 2003). One of the most important discoveries
during the events of late 2002 and early 2003 was that the Pernicana
Fault System is not only 9 km long, as previously believed, but extends
from the Northeast Rift down to the Ionian Sea, and possibly continues
offshore, over a distance of at least 18 km (Neri et al. 2003).
The eruption produced a number of small scoria cones along the fissure
on the Northeast Rift and a cluster of huge cones at the vents on the
southern flank. These latter have once more completely changed the topography
of what was once known as the "Piano del Lago" (the plain
of the lake). Until 27 October 2002 this area bore the scars of the
2001 eruption, most of it being covered with virtually inaccessible
lava flows and smaller and larger pyroclastic cones. In early November
2002 the formerly rugged surface had transformed into a rolling plain
of ash, which made excursions on foot much more easy. Unfortunately
the area was subsequently covered by new lava flows and excursions will
be very difficult for some time. The abandoned station of the old cable
car of Etna (partially destroyed by an eruption in 1983) has been replaced
by the lowermost of the new cones, this will give a peculiar taste of
thrill to those who until shortly before the eruption used that building
as a shelter at night. The new souvenir shop and bar erected by the
mountain guides early in 2002 at 2760 m elevation has vanished under
the cover of pyroclastics, while the Torre del Filosofo mountain hut
at 2900 m elevation is still standing. Those who in the past arrived
at the Piano del Lago enjoyed a splendid panorama of the summit cone
complex; this is now largely concealed by the new cones at the fissure
at 2700 m elevation. The largest of these cones, formed where the terrain
was at 2750 m until the eruption, now stands about 200 m above that
elevation, while a second cone a little upslope is nearly as tall. The
sheer size of these new cones dwarfs that of Monte Josemaria Escrivà,
formed in 2001, which itself is a fairly prominent feature.
The precise volumes of lava and pyroclastics emitted during the 2002
eruption has yet to be determined but can be estimated to lie in the
range of 30 million cubic meters of lava (nearly two-thirds of these
emitted on the southern flank) and 40 million cubic meters of pyroclastics
(nearly exclusively emitted from the southern flank vents). These values
were included in the paper on Etna's 2001 eruption by Behncke and Neri
(Bulletin of Volcanology, in press) and seem to be confirmed by other,
independent calculations. In terms of magma volume, this is not exactly
an enormous eruption for Etna, but it ranks among the more significant
of recent decades.
Outlook.
The 2002-2003 eruption came exactly 1 year, 3 months and 10 days after
the beginning of the 2001 eruption. This is a fairly short interval,
even considering that between 1971 and 1993 flank eruptions occurred
at a mean interval of 1.7 years. Yet, in spite of the very brief period
of precursory symptoms, this is no surprise. After the 2001 eruption,
several scientists knowing Etna had assumed that the next eruption would
occur within one to two years, and in fact the eruption fell exactly
into this time window. The assumption is based on the historical behavior
of the volcano, which has undergone significant fluctuations during
the 400 years of reasonably complete documentation since 1600. It seems
that flank eruptions tend to occur in series, and the 2001 eruption
was interpreted as the first in a new series, similar to the striking
series of 13 flank eruptions between 1971 and 1993. It thus seemed probable
that more such eruptions would occur at relatively brief intervals over
a period of 10-20 years. The 2002-2003 eruption is the second in the
new series, and it is well possible that the third one is not too distant
in the future. Furthermore, the volcano was extensively fractured during
both eruptions, which in the future might allow magma much more easily
to rise under the flanks of the edifice. Last but not least, Etna has
grown progressively more active during the past 50 years. This means,
it is erupting more frequently and more vigorously than during the 280
years before 1950, and its productivity, or output, is increasing. There
is no reason to believe that this trend will invert in the near future.
Flank eruptions must thus be expected to occur at intervals ranging
from 1-3 years, and some of them might be much more voluminous and potentially
hazardous than the latest two eruptions.
The 2002-2003 eruption is one of the most explosive flank eruptions
of the past 150 years, and it shows that Etna is a potentially explosive
volcano, and it has been so since long time. Nearly all of the flank
eruptions of the past 100 years have been relatively benign and emitted
mostly lava, and thus the local population has been lured into the belief
that Etna is a "good volcano". But a short look at the record
of its historically documented eruptions shows that the rather effusive,
non-explosive behavior of the 20th century was unusual.
Part of the explosivity of the 2002-2003 eruption might be due to the
water-rich nature of the magma rising from an "eccentric"
reservoir below the southern flank. It clearly indicates that this magma
had lost virtually no gas before ascending, in contrast to the magma
erupted from the central conduit system (and on the northeastern flank),
which had degassed to some degree during the months before the eruption.
The fact that this magma has appeared for the second consecutive time
might be taken as an indicator that future eruptions will be fed from
the same reservoir as well and therefore be as explosive. However, an
additional factor controlling the explosivity of an eruption is the
interaction of magma with external water, such as a shallow aquifer.
This was the case during the 2001 eruption (at Monte Josemaria Escrivà),
and it was probably again the case at the new cones at 2750 and 2800
m elevation on the southern flank. In fact, ash from the first day of
the 2002-2003 eruption that arrived on the Greek island of Cefalonia
during the following 24 hours was determined to be of phreatomagmatic
origin (Dellino and Kyriakopoulos, 2003)
Etna returned quiet on 28 January, to the enormous relief of everybody
nearby (the residents, because they no longer received ash and more
ash and still more ash; the volcanologists, because they could relax
to some degree after months of stress, although Stromboli still kept
them busy). But this quiet concerns only the eruptive activity. In terms
of seismicity, the volcano is still restless, and it has to be checked
whether the continuing seismic activity is due to the adjustment of
the edifice to the major displacements at the beginning of the eruption,
or if it has already started to recharge for its next eruption. Seismicity
dropped to relatively low levels in the spring of 2003, but since mid-June
2003 is again slightly elevated, and much of this is probably related
to continued displacement of the eastern flank.
References
(very few so far, but this list will certainly grow)
Acocella
V, Behncke B, D'Amico S, Maiolino V, Neri M, Ursino A, Velardita R (2003)
The 2001 and 2002-2003 eruptions of Mount Etna (Italy): Evidence for
different triggering mechanisms. Abstract presented at the Annual Workshop
2003, Pantelleria, Sicily (23-28 September 2003) on: Seismic Phenomena
Associated With Volcanic Activity. Here, the first results of a multidisciplinary
study of the seismicity and deformation accompanying the latest two
eruptions are presented, which will be treated in a more extensive publication
in an international scientific journal
Behncke
B, Neri M (2003) The July-August 2001 eruption of Mt. Etna (Sicily).
Bulletin of Volcanology 65: 461-476; DOI 10.1007/s00445-003-0274-1.
This paper essentially deals with the predecessor of the eruption described
here but due to delayed refereeing was accepted only once the new eruption
was in progress, and this gave us the possibility to insert a brief
note on that event, including the first approximate volume estimates
as we sent the final proofs after the end of the 2002-2003 eruption
Branca
S, Carbone D, Greco F (2003) Intrusive mechanism of the 2002 NE-Rift
eruption at Mt. Etna (Italy) inferred through continuous microgravity
data and volcanological evidences. Geophysical Research Letters 30,
2077; DOI 10.1029/2003GL018250.
Describes a striking microgravity decrease shortly before the beginning
of the 2002-2003 eruption, evidence for flank slip serving as a trigger
for the magma intrusion into the Northeast Rift
Dellino
P, Kyriakopoulos K (2003) Phreatomagmatic ash from the ongoing eruption
of Etna reaching the Greek island of Cefalonia. Journal of Volcanology
and Geothermal Research 126: 341-345, DOI 10.1016/S0377-0273(03)00154-9
Neri
M, Acocella V, Behncke B (2003) The role of the Pernicana Fault System
in the spreading of Mt. Etna (Italy) during the 2002-2003 eruption.
Bulletin of Volcanology; DOI 10.1007/s00445-003-0322-x
(in press; published
on-line on 5 November 2003). This article describes in detail how the
Pernicana moved during the 2002-2003 eruption and presents a preliminary
interpretation of the relationship between flank slip and the eruption
Other
web sites dealing with the 2002-2003 eruption
During the eruption, the two principal sources of information (updates,
photographs, and other graphic material) were:
The "official" Etna
2002 eruption web site at the Catania section of the National Institute
of Geophysics and Volcanology (INGV) (in Italian)
and
Charles Rivière's Etna
home page, with frequent updates and photos (in French)
Like in 2001, Lisetta Giacomelli and Roberto Scandone of the University
of Roma 3 created an incredibly informative and well-illustrated web
page, which unfortunately is only available in Italian:
Eruzione dell'Etna 2002
Furthermore two web cams pointed on the southern flank of Etna were
accessible at the web site of:
Davide Corsaro, of the Hotel
Corsaro, located at nearly 2000 m elevation on the southern flank of
Etna
but are currently not active
The last moments of Piano Provenzana, the tourist complex on Etna's
northern flank that was devastated on the first day of the 2002-2003
eruption are shown at the web site of:
The Etna volcanological and mountain
guides (etnaescursioni.it)
Impressive photographs of the first day of the eruption on the Northeast
Rift and the drama of Piano Provenzana are provided by:
Finocchiaro Fotografi of Linguaglossa
(Note that the date of the beginning of the eruption is wrongly given
as 24 October 2002; actually the eruption began on the Northeast Rift
on 27 October)
Two further web cams, located at Riposto (east-northeast of Etna)
show a wide-angle view and a close-up of the volcano; these are provided
by:
Albanet.com
Alain Melchior presents interesting digital models of the lava flows
of the 2002 eruption and has numerous captures from Italian television
news of the eruption
Eruption 2002 de l'Etna
(du 26/10/2002 au 28/1/2003)
One could expect some high-quality photography of the eruption at
"Stromboli On-Line", and Marco Fulle's photos do fulfill all
expectations...
The 2002 eruption of Etna at
Stromboli On-Line
The same is true for Tom Pfeiffer's photos, which are among the most
spectacular of the 2002 eruption so far available - Tom was lucky to
be at Etna on the evening of 27 October and photograph the most spectacular
phases of activity on the Northeast Rift:
www.decadevolcano.com
This is a relatively poorly known site, created in 2000, which has
photos and spectacular video clips of the 2002 eruption (and of the
activity in 2000 and 2001 as well):
Etna2000.com by Simone Genovese
Another web site that has escaped attention thus far, but deserves
to be visited (good photos and movie clips, including one of the spectacular
explosive eruption at the Voragine on 22 July 1998):
Malosito/Geoarchive by Marco
Busetta
Very spectacular photos of the still-erupting crater at 2750 m elevation
on the southern flank (seen from the Torre del Filosofo area) plus a
nice map of the upper southern flank of Etna are available on
Thorsten Boeckel's web site
No less spectacular, the view of the eruption from the International
Space Station (NASA):
The eruption seen from space
on 30 October 2002
...and, of course, there are photos, updates and video clips at
www.vulcanoetna.com
Much information (in Italian) is offered by the Catania-based newspaper
La Sicilia
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