Extremely strong activity, 17-23.10.1999 Video
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Marco Fulle, Roberto Carniel and Jürg Alean visited Etna, at various times, during the
phase of extremely strong activity. After Marco's photos, we are proud to present you a highlight from Roby's video.
24 Oct 1999 h. 16:45. Bocca Nuova has been relatively quiet all day long, despite our "forecast" of a paroxysm for 7:30 in the morning :-). During the afternoon, a short excursion below the South East Crater reveals that a lava flow is coming out of a vertically split hornito. It does not reach the "quality" of the Easter flows, nor of those witnessed by Jürg a few days later. But there is still the duty of the reporter... 539 KB
25 Oct 1999 h. 12:04. Today BN seems a bit more fit! Although the plan is to reach the edge of the previous days lava field, along the way it's very difficult to resist the temptation of stopping to film, and sometimes these pauses last much longer than expected (reason of Marco's repeated phrase: Ma dov'è Roby???). NW vent in BN produces a cloud of bombs that fly up and down almost continuously. 1.7 MB
25 Oct 1999 h. 12:16. At a larger scale, we observe here the activity of SWV of BN. In this moment it ejects, with discrete explosions, incandescent material mixed with dark ash, that creates a nice chromatic contrast with the white of the vapour in the background. A spherical symmetry is rarely observed. Most of the times the high velocity of the gas emission produces more vertically elongated shapes. 1.7 MB
25 Oct 1999 h. 12:25. The SW vent in BN produces the explosion of a bubble that throws fragments as bombs with spherical symmetrical trajectories. The final enlargement of the field of view allows one to follow the trajectories of the most far-reaching bombs, some of which impact on the crater flank towards the operator (on the right), while some other fly towards the lava field (on the left, not visible from here). 2.0 MB
25 Oct 1999 h. 12:36. Finally Roby manages to stop videoing for a while, and he reaches Marco on the edge of the lava field. But this is the only short sequence that Roby manages to shoot of the front of the new lava flow that rapidly descends along the southern edge of the previous lava field. The reason will appear clear very soon... Please note the continuous degassing from the lava, the fall of the aa blocks from the top of the flow in front of the front (!), and a curious pinnacle that stands isolated on the left of the flow. 824 KB
25 Oct 1999 h. 12:48. Roby moves the camera first towards the NWV of BN, where the flying of small bombs is sometimes interrupted by the appearance of big lava blobs, and then, following the rim, towards the ocher smoke that starts to flow in remarkable quantities from several fractures on the flank of BN in the NW direction (fractures that will soon suggest to stop videoing). But there is someone else that tries to stop Roby from filming the fall of blocks from the flank of the crater... 2.0 MB
25 Oct 1999 h. 12:49. The strong spherical symmetry of the bomb trajectories clearly indicates their origin in the explosion of a single big bubble. In this case the source is the NW vent. Some of the bombs impact on the flank already made unstable by the fractures filmed before. This starts the first landslides of material heated by the intrusion of fresh lava just below, accompanied by the raising of considerable amounts of ocher smoke, descending along the slope. I don't know why, but the volcano guides observe the phenomenon with us but never shut their jeep engines off! 1.3 MB
25 Oct 1999 h. 12:57. The flank of Bocca Nuova has become extremely unstable, and every impact of a new bomb may cause the collapse of greater and greater amounts of material, which average temperature is probably also continuously increasing due to the intrusion of the lava from below and from the side. Here we observe a first episode of noteworthy size. Please note the detachment of some blocks from the flank, that contribute to increase the size of the collapse. The smoke becomes turbulent, and the new explosion from NWV won't better the situation... 1.7 MB
25 Oct 1999 h. 13:01. This video lasts 51 s, i.e. 2.6 MB, but it's really worthwhile to download it all :-). The activity at NWV is now very intense. As long as the spatter falls back into the crater, everything proceeds smoothly, but as soon as some bombs manage to impact on the external flank, now completely unstable, a collapse much bigger than all the previous ones is started. The blocks fragment and multiply the size of the landslide, that soon, also probably thanks to the high temperature, transforms into a real pyroclastic flow, obviously on a much smaller scale if compared to e.g. Unzen or Montserrat. However, the flow is spectacular and it ends, according to theory, with the deposit of the heavier material and the upraising of the lighter remaining particles, which form a column that is in turn pushed backwards by the wind, again towards Bocca Nuova.
25 Oct 1999 h. 13:05. Only four minutes later the flank does not really offer too much safety. The landslides follow each other very often, and as can be clearly seen in the video, all the flank sector appears very different from the beginning of the paroxysm. Moreover, the explosion of a really spectacular bubble covers with bomb impacts the flank of Bocca Nuova towards us. The jeeps of the volcano guides go further away, and Marco fills the soundtrack with alarming invitations to go somewhere else :-). 900 KB
25 Oct 1999 h. 13:34. In fact, remaining in the area was not such a good idea... After moving we see the crater from a different perspective. It's shocking how a sector of the BN flank was uplifted by at least 20 metres, and then dragged outside by the lava which has found its way below it. 1 MB
26 Oct 1999 h. 10:33. The day after... Having nothing better to do, we decide to circumnavigate Mt. Etna, discovering the road is not only very long but also full of obstacles and unforeseen events. Here the "600" rented by Tom Pfeiffer finds its way with great difficulties in the middle of a "gregge" and his "pastori". Tom speaks his perfect italian (one of the N languages he speaks, btw...) commenting the not-exactly-orthodox way of keeping the cattle... 730 KB
26 Oct 1999 h. 18:10. In the late afternoon we are again under the W flank of Bocca Nuova, which appears a bit more stable than yesterday. We have now the proof that the lava has really found a way under the block uplifted by 20 metres. A new vent can in fact be observed on the flank itself, and the front of the new flow, after having tried to cut our way back to the North side, stops immediately when we climb to film and photograph it, in accordance to Murphy's law. Tom Pfeiffer is again the guest star. As a good geologist, he applies the rule "If I do not use my hammer on it, I have not experienced it really ...". 370 KB
26 Oct 1999 h. 18:51. The evening features an intense strombolian activity, more and more spectacular as the dark comes. Notwithstanding the fact that Roby's video collection now includes two new tapes full of beautiful strombolian explosions, we decided to offer you a very original point of view, which sheds a new light (literally!) on strombolian activity. The footage you see here is infact shot using infrared light. Besides the observation that with infrared you can see many more bombs than you can see with your own eye, it's interesting to observe also the incandescent gas and the presence, in the lower left corner, of the vent cited before, still slightly active. 1.5 MB
27 Oct 1999 h. 10:46. For Marco and Roby the time of departure for Friuli-Venezia Giulia is approaching ineluctably. There's really no time to climb to the craters, so we profit once again from Tom's rented "600" to go to Mt. Intraleo, from where we observe, at the maximum zoom allowed by the videocamera, the summit activity, while a number of lava flows are descending the slope of the volcano, flows that later on will cut the "forestale" road. Sometimes the summit activity, mainly concentrated in the NW sector, increases its intensity and crosses the vague border between "normal" and "paroxysmal". The video is mute for obvious reasons of distance, although a fly flying near the videocamera entertains the listener of the original videotape. 2.7 MB
|Video: R. Carniel|