Updates May-November 1997
28 November 1997
The eruption in Etna's summit craters continues. Today during the late forenoon, the cloud cover over the mountain opened, permitting the view of a huge vapor column rising almost vertically to about 1500 m above the summit. This unusually large plume was due to an approaching cold front which led to increased condensation. After sunset, quasi-continuous Strombolian bursts from SE Crater and fluctuating bright glows above Bocca Nuova could be seen from Catania (Palazzo delle Scienze). The telecamera maintained by the Istituto Internazionale di Vulcanologia showed occasional explosions and brightly illuminated gas clouds at Bocca Nuova and Strombolian activity at SE Crater (see the images taken from the IIV site: image 1 taken at about 1715 local time, and image 2 taken about 15 minutes later). No lava outflow is occurring at this time, but more (small-scale) overflows from SE Crater onto its southeastern flank are probable. The large intracrateral cone within Bocca Nuova is probably growing fast, and - provided the activity continues in the same manner as now - the crater will be filled within the next few months.
An episode of spectacular lava fountaining from Bocca Nuova occurred on 25 November. Huge bursts of incandescent bombs developed into a continuous fountain that apparently rose from the southeastern eruptive center in Bocca Nuova. The paroxysmal phase of this activity lasted from about 2000 until 2300 that evening. Eyewitnesses described the activity as "stunningly beautiful". Clear weather for the first time in many days permitted an unobstructed view of the activity from Catania, and from as far away as Siracusa (some 80 km to the south).
7 November 1997
A visit to three of the four summit craters on 6 November revealed very weak and erratic Strombolian activity from SE Crater where for the first time since many months there was no lava effusion (guides at Torre del Filosofo reported that a small lava flow had spilled over the low SE rim of the crater three days earlier); the northern eruptive center in Bocca Nuova was vigorously active (though less vigorously than in September-October) with very few bombs falling on the N rim of Bocca Nuova. The cone at that site has grown significantly higher and its summit appears to be no lower than 50 m below the NW rim of Bocca Nuova. The diameter of the summit crater on the cone is about 30-50 m, about half of the diameter in September-October, and there are two smaller but vigorous vents on the upper E flank of the cone. The southeastern eruptive center in Bocca Nuova erupted much less violently than it did in previous months, with no bombs falling onto the crater rim; on the crater wall above that eruptive center, a large overhanging hollow has been carved out of the crater wall by the explosions of that center, and large collapses on that side will probably occur in the near future. This will probably destroy much of what remains of a cone formed in 1964. The Voragine was explosively active from the conelet in the central part of its floor, and another weakly explosive vent had formed in its SW part, at the base of the narrow septum separating the Voragine from Bocca Nuova. Bad visibility precluded any clear view of the crater floor and it is not known whether there have been any new lava flows in the Voragine after the late September effusive activity. No eruptive activity was seen at NE Crater, but visibility was poor because the vapor plumes from Bocca Nuova and Voragine was carried right over it. Etna is covered with some snow and today weather appears to be worsening, so this may have been the last summit visit for several months.
2 November 1997
After a period of bad weather, Etna is plainly visible from Catania today. At dusk, there are continuous Strombolian bursts from SE Crater while the intense glow over Bocca Nuova that has been visible in early October has ended.
14 October 1997
Visits to the summit craters in late September and early October revealed continuing vigorous activity from Bocca Nuova and SE Crater while more sporadic, though spectacular activity is occurring from the Voragine and NE Crater.
Bocca Nuova's activity is gradually increasing, with fluctuations, and the crater is contiually being filled in. The northern of its two eruptive centers has a broad cone with a crater that may be between 50 an 100 m wide which at times is completely filled with fountaining lava; in other moments the top of the magma column is covered with scoria and fountaining occurs from smaller open vents in various places within the cone's crater. Fountains often launch fluid spatter and bombs high above the rim of Bocca Nuova, and large ejecta may fall outside the crater, even to a distance of some 100 m away (lookout on the NW rim of the Voragine). Ejections onto the outer NW wall of Bocca Nuova occurred every 5-10 minutes during a 28 September visit, and at similar intervals onto the N side during 9-14 October. Bombs as large as 40 cm in diameter have recently fallen onto the area where the best views of the erupting cone in Bocca Nuova can be obtained. Less continuous, but very powerful explosions occur from at least three vents in the southeastern eruptive center in Bocca Nuova, at times sending pyroclastics all over the southern flank of Etna's summit cone.
The cone growing within SE Crater has grown to about the height of the NW rim of the crater where the rim is highest. Explosive activity is occurring in much the same manner as during previous months, and lava effusion continues from vents in shifting locations on the flanks of the cone. While effusive vents were active on the W base of the cone during the period 10 August - mid-September, lava again issued from E flank vents in late September, causing renewed overflows onto the outer SW flank of the cone. The new overflows did not reach beyoud those of late July and early August, suggesting a constant low effusion rate.
The active vent on the floor of the Voragine has sporadically erupted since late July, and the first effusive activity from this vent since many years occurred in late September, forming a small lava field around the conelet on the floor of the Voragine. Strombolian activity from the cone was weak on 28 September but very vigorous on 9 October; one day later it was again much weaker.
NE Crater frequently emitted ash plumes during the first week of October, and on the evening of 10 October, incandescent ejections rose as high as 50 m above the crater rim. these ejections had only few bombs, but in one case, a bomb fell onto the outer SW slope of the cone, not far away from the Voragine lookout.
The first snow of the forthcoming winter fell on Etna last night, and observations of the ongoing activity will probably be hampered by bad weather in the next months.
1 September 1997
During late August, lava ejections from Bocca Nuova have become significantly more vigorous, becoming a potential threat to people who stay on the crater rim. Both the southeastern and northern eruptive centers in this crater often eject fluid lava bombs outside the crater, with many bombs falling on its S rim. Occasional explosions eject boombs on the lower south flank of the central cone. Passage from Bocca Nuova to SE Crater along the south rim of Bocca Nuova has become extremely dangerous, but bomb fallout has also affected the N rim of Bocca Nuova where a track leads to the Voragine. The number of active vents in Bocca Nuova increased to seven on 28 August but was down to five two days later. Explosions from the southeastern vents are accompanied by loud roaring noises which at times last for several minutes (while explosions from these vents were very brief until early August). The largest bursts from the northern vents are strikingly noiseless.
The intense bombardment and possible seismic or air shocks from the explosions have led to widespread collapse on the eastern side of Bocca Nuova, lowering significantly the narrow septum (known as "diaframma" among Catanese volcanologists) between this crater and neighboring Voragine, and eroding further the remains of a cone formed in 1964.
Highly picturesque Strombolian and effusive activity continues from SE Crater whose intracrateral cone is now looming above a gap in the NE rim of the crater when seen from coastal areas east of Etna. During a visit on 30 August, lava fountains rose up to 150 m above the cone's summit, and three vents were active at times. Lava effusion occurred from the NW and E sides of the cone, but much of the active lava had crusted over, feeding small flows from ephemeral boccas. Significant infilling of the deep southern part of SE Crater since effusive activity shifted to the cone's NW flank some time before 11 August. Before that shift, lava had repeatedly spilled onto the SE flank of the cone, forming a small field of partially overlapping lava tongues no more than 200 m long, and minor overflows had occurred, presumably during the first days of August, onto the NE flank of the cone.
Activity at NE Crater began during the second half of July and was characterized by occasional ejections of incandescent bombs from a deep pit in the central part of the crater. Much of this activity does not eject any material (except fine ash) outside the pit. Due to the instability of the pit's rims and dense gas emissions, observation of the intra-pit activity is next to impossible.
A very small cone began to form on the floor of the Voragine in late July, and Strombolian activity has been periodically observed at this cone, most recently on 5 August. On 30 August, the cone was found mildly steaming, and the surrounding deposit of black scoriae was partly covered by blocks that had collapsed from the septum between Voragine and Bocca Nuova (see above).
23 July 1997
While activity at Bocca Nuova and SE Crater is continuing much as it has done during recent weeks, photos of the activity are now available. Go to this page to see them.
21 July 1997
Lava has begun to overflow from SE Crater on the night of Saturday-Sunday (19-20 July). The first lava to erupt onto the outer slopes of the cone since 1990 has formed a very small tongue spilling over the low ESE rim of the crater, reaching no more than 30-40 m in length. Explosive activity occurred from three boccas aligned E-W on the intracrateral cone during the 19-20 July visit, the largest and most vigorously active being situated below the cone's summit on the upper E flank. Lava issued from this vent in surges coinciding with eruptive cycles that lasted 10-20 minutes, and were separated by quiet intervals up to 15 minutes long. News about a possible reactivation of the Voragine crater on 13 July (passed along by mountain guides) were uncorroborated as of today, and it is possible that the ash plume seen above the Voragine that day by observers in Catania was caused by internal collapse of the crater, rather than by the reopening of the central pit which was found obstructed during recent summit visits. Activity at Bocca Nuova is continuing from the two eruptive areas in the SE and NW of its floor.
Strombolian activity and lava emission at SE Crater on the evening of 11 July 1997 is visible in a photo that you can view here (ca. 40 k).
18 July 1997
Bocca Nuova and SE Crater are in a state of persistent activity. Visits to the summit during June and July revealed a graduall filling of these craters by intracrateral cones and lava flows. Bocca Nuova has two areas of activity, one in its SE part and one in the NW, both displaying intense Strombolian activity, at times accompanied by lava emission from boccas near the explosive vents. The number and size of the boccas varies rapidly. During the most recent visit on 16 July, a large spatter cone with a crater 20-30 m wide had formed in the NW area of activity, where there had been three small vents only five days earlier. The crater of this new cone was filled with vigorously boiling and spattering lava. Explosions from the SE eruptive vent occurred about every 3-5 minutes, at times ejecting bombs high above the SE rim of Bocca Nuova, that is, about 150 m above the vent. SE Crater has an intracrateral cone in its northern half, the cone now being as high as the crater rim (about 50-70 m above the lowest part of the crater floor). Lava flows issue more or less continuously from boccas on the upper S and SE flanks of the cone, forming a complex lava field on the S, SE and E sides of the cone. The lava fill was only 10 m below a low point on the SE rim of SE Crater during the 16 July visit; thus an overflow onto the outer flanks is possible within days to weeks. Explosive activity from the summit of the intracrateral cone is visible from Catania at night, 30 km away from Etna's summit.
27 May 1997
Activity at Etna's western summit crater, Bocca Nuova, continued through early May 1997. On 5 May, scientists of an international scientific meeting (including GEOMAR staff) climbed to the rim of Bocca Nuova and observed small-scale Strombolian activity from a funnel-shaped vent in the NW part of the crater floor. The photo at right has been kindly supplied by Eduard Harms, GEOMAR. A second vent adjacent to the active one was apparently inactive.
The activity in Bocca Nuova is continuing intermittently since July 1995 and has involved the building of small cinder/spatter cones as well as emission of minor lava flows on the floor of Bocca Nuova. Northeast Crater and Southeast Crater have been active through November 1996 and March 1997, respectively but were only strongly degassing during the 5 May visit. No observations were made at the Voragine crater.