546 



NATURE 



[October 13, 1923 



The Recent Eruption of Etna. 



By Prof. Gaetano 1' 



tlif \.\\y\ Vulcanoluu;!' .il III mute. 



DURING the last ten years Etna has exhibited 

 various phenomena of considerable interest, 

 especially at the lateral crater which appeared in May 

 191 1 on the north-eastern slope of the central cone at 

 the 3100 metre contour. This was the forerunner of 

 a more violent eruption in September of 191 1, when 

 the new north-east crater became more active than the 

 central one. 



In 191 7 a luminous column rose like a fountain a 

 thousand metres above the north-east rratcr, and 

 about 50,000 cubic metres of very fluid la\a wtre 

 poured out in about half an hour, without either 

 rumblings or shakings of the ground. This afforded 

 most striking proof of the resistance of the structure 



Fig. I. — Sketch-map of north-eastern part of Etna, showing track of lava 



of the volcano to the enormous forces propelling the 

 lava, which was raised not by the force of volcanic 

 gases, but by powerful static pressure. 



In June 1922 the activity of the north-east crater 

 was resumed, and there were feeble explosions. In 

 the spring of 1923 its activity increased still more, and 

 at the foot of the explosion-cone which had been 

 formed, some streams of lava appeared and spread 

 out in short many-branched flows over the snow-fields. 

 It was very interesting to observe the phenomenon 

 of the hot lava spreading over the snow without 

 melting it, but rather transforming it into ice under 

 the weight. 



The activity of the north-east crater continued until 

 the outbreak of the eccentric eruption, which was 

 preceded by the great explosions in the central crater, 

 where^ on June 6 last, the throat of the volcano, 

 obstructed since 1918, reopened and ejected gigantic 

 pine-tree clouds of reddish ash to a great height above 

 the crater. 



Following this the sky remained obscured for many 



NO. 2815, VOL. 112] 



days, and o!)s( r\;iiions became imp>ossible. At 2:0 

 A.M. of June 17 tin- inhabitants of the northern slop'- 

 of the volcano were rudely iiuiikcned by deep rumblint^ 

 and shakings of the ground, while near the craters <<\ 

 1809, at the 1500 metre altitude, there rose imposiiu 

 outpourin: ' ' i ; meanwhile other craters opend 

 and ()tli( I ;.in lower down the mountain, until 



at 4 A.M., at tlie 2000 m. ( ontour on the western sKjI"- 

 of Monte Ponte di li rro. and at the south-westi rn 

 foot of Monte N'fp), tlun- were c'-tahlished definitd;. 

 the craters of tlu- main flow . TIk tlow of Monte Nero, 

 which was feel)le and ot short duration, ran over the 

 bed of the 1879 lava for aljout 3 kilometres, but the 

 niniitli liuiii uliii h it flowed closed on June 21, whereas 

 the flow from Monte Ponte di 

 Ferro, which was of much greater 

 extent, invaded the pine-forest uf 

 J\tarronc and, rapidly running 

 down the eastern side of the lava- 

 flow of 1 91 1, reached in a few 

 hours the Piano dei Filici, where, 

 spreading its front, it headed 

 towards Cerro and destroyed the 

 vineyards and the nut-plantations 

 of the Piano di Pallamelata (see 

 Fig. i). 



In ten hours tlu- la\a had 

 travelled about 7 kilometres, 

 faliinir in that distance 1200 

 metres, but as soon as it reached 

 the plain, as has happened in 

 other eruptions of Etna, it slack- 

 ened the speed of its advance, 

 spread fan-wise, and swelled like 

 the carapace of a tortoise. Thus 

 it happened that the front of the 

 lava, whii 1) on tlie cM'ning of 

 June i; nit i kilometre 



from tl.c ti.vwUi-Etna Railway, 

 reduced its speed, and did not 

 of Castidione until the niirht of 



invade the station 

 June 19. 



On June 20, when the Kini; of Italy arri\ ed in the 

 region devastated by the Ia\ a-i1o\v. tlic front was already 

 I kilometre in width, and was still advancing at a 

 speed of from 10 to 15 metres per hour. On the 

 followinu day. when the Premier, Signor Mussolini, 

 arrived, the flow had reached the foot of Monte Santo 

 and continued to spread out slowly like a fan, envelop- 

 ing the last few houses of the 'it.-ni <ut,nrb and 

 threatening the town of Liniiu. nately, 



however, from that dav the impeui> ni im ;, wi began 

 slowly to diminish, and bv June 26 its rate ol advance 

 was reduced by a half. The front of the lava-flow, 

 not being sufliciently fed from its source, stopped 

 definitely on June 29, but on the Piano di Pallamelata, 

 on the eastern side of the flow, a fresh branch was 

 formed, which at first threatened to give a new direction 

 to the devastating torrent. In the meantime, higher 

 up on the lava-flow there were further additions and 

 lateral outbreaks. At some points the crust of lava 



