Etna Stromboli 1991 - 2000 ; Sofi 99 ; by Boeckel / Heidl ; 6.4.00

South East Crater, 6th.of April 2000

However..., you can't imagine which feeling of fortune, inspire and respect Andreas Heidl (camera-man), Gertraud Keim, Werner Zagler an me ecperienced, to become witnesses of this very strong eruption after a three day waiting period at the Td'F. Since the Monday eruption at the third of April , the days and nights were filled up with snowstorms up to 120 Km/h, thunderstorms, hail and problems to produce yellow snow. ( self-experiments failed!). It was also necessary to install a night watch, to have the security, not to pass anything. In case, night watches are very expensive an so we had to stand by our own in the clouds.

filos_trist_c.JPG (6156 Byte)

The TDF in dense fog....Iceflowers....A.Heidl W. Zagler and G. Keim during the eruption

Jacques Durieux and Jacques Barthelemy which had a former meeting with Gertrud and Werner at the Piton ( Reunion), were also holding out with ' fromage, French wine and a strong good will at the Td'F. This very nice meeting gave us a good chance to exchange scientific info and volcano stories

During the morning hours the weather conditions changed and became very good. At 11.30 the first sign of a new activity was announced by a little brown cloud. The eruption developed and at 12.00 the first weak burst were recognized. The eruptions are getting more powerful and reached at 12.30 the vehement top.

The main lava / lapilli column had an altitude from apprx. 300- 400 meters. Particular high jets reached the height of apprx . 600 up to700 meters!. During this event the mighty ash-cloud turned from NE direction to SE ( 90°). The following reaction was that we could feel the radiating heat of this enormous heated mass.

12.35 ... The phase is now going on for 35 minutes and did not made the appearance to end. So I had the chance to run down the slope of the refugio Td'F (7) to make some special photos. Image 8 is showing the Double-Jacques standing before the ash -curtain which was turning slowly in our direction.

12.40... the blasts are changing now to the NW direction and bombs up to an diameter of three an more meters are treating the slopes of the Bocca Nuova ( flight distance up to 800m), and converted them into a little moon- landscape.

The not destroyable refugio Torre del Filosofo

At 12.55 the eruptions decreased (14) and at the time of 13.25 the whole SE-conus was quite again. This was also the first possibility to test my birthday-Flachman (15) who is determined from Christine and Martin and Nikkl for special violent volcano- events.



Cleaning of the Optics

This eruption was one of the strongest since the 15 February were I have been also witness. During this time I had the same feeling like in February. The last sequence of the event showed us again what an enormous power this volcano has.



After observing the eastern flanks of Southeast we discovered a Lavabomb 100 meter from the base with an volume of approx. 20-30 m³. This "bomb?" was glowing inside and was one of the biggest I have ever seen!!!!

The newland

here you can see this oversized 'Lavabomb`?

Look at the hompage of Boris Behncke for more information. Actual photos from the earliest and latest Etna eruptions.

The aerosole-ring-corner

Impressions of air-calamaries during the 2/6.april.2000 waiting time around the TdF

Cinema

This two images shows the same aerosole ring leaving the Bocca Nuova in eastern direction. This ring kept 15 minutes his exactly form, reached maybe the height of 4000 - 5000 m, and was carried by the strong wind in east-direction to the sea. In the days of 2-6 april when good weather- conditions has been a rarity, the vent of the Bocca Nuova "produced" every 10 minutes well-formed rings in the size of 20m up to 50m. This rings can get a diameter up to 200m after a drifting time of may 5 - 15 minutes, before they break up and disappear.



When you get the chance to have a closer view to this rings you can see more details, and for me I had one big question. What mechanism of currency let this rings appears like home or pub made bocca smoke- rings?



The beginning supposition is: a homogeneous atmosphere currency and the hot gases must leave the vent very symmetric and fast. The involved condensing water caused by hot/cold air meeting makes this 'aerosole ring' visible. Then the hot driving up steam is pushing through the rough- ring, and the colder air is slipping at the outside down. The forming process starts while the whole thing begins to rotate....at the end very fast. The cross-section of the rotation - form you maybe can compare with a little inside closed tornado* because the whole thing looks like an inner tube...

May a tornado can only build up his inner low pressure because he has a solid resistance by the ground and can exist for longer times (the other end is 'open'). if you would join the ground part of the tornado with his upper (open) part, he will suck itself without resistance. In case of the ground-free rings of Etna, the inside lower- pressure will develop a screwing horizontal currency like a carousel. The gravity of horizontal rotation and the itself contraction of the lower-pressure (inside the tube) makes the ring stabile for a longer time by supporting the 'vertical' rotation.  May you can take into consideration the inside volume (diameter of the tube), which is steady decreasing in the cold environment, and the 'wall' parts are getting also faster coming nearer to the tube axis.

The ultimative Etna ring contribution. Phantastic photos und explanations to this and other phenomenon.