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30 years ago: inferno near Randazzo | by etnaboris
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30 years ago: inferno near Randazzo

17 March 2011 marks the 30th anniversary of one of the most terrifying and destructive eruptions of Mount Etna volcano in Sicily in the past few hundred years. That eruption nearly brought doom to the small town of Randazzo on the north-northwestern flank of the volcano, but the unusually fast-moving lava flows narrowly missed the town and a nearby village, although they destroyed a few hundred isolated buildings from small cots to sizable weekend homes. The 1981 Randazzo eruption serves as a reminder that Etna is capable of producing eruptions that develop incredibly fast, with kilometer-long fissure systems extending down to low altitude and very high rates of lava emission generating unusually mobile lava flows. In 1981, a relatively sparsely populated sector of the volcano was affected; if a similar eruption were to occur on the opposite, south-southeastern side of the mountain, it would possibly produce the worst disaster seen at Etna in the past two millennia.

 

During the 20th century, Etna showed higher levels of activity than during the previous two centuries, especially since 1950. Frequent summit eruptions, often nearly continuous for many years, reshaped the morphology of the summit of Etna, where at the beginning of the century there was one single crater; by the 1970s the number of summit craters had grown to four.

 

In addition to the intense summit eruptions, there were 23 eruptions from new vents opening on the flanks - so-called flank eruptions. More than half of these occurred during the interval between 1971 and 1993, one of the most frantically active periods at Etna in recorded history. Following three relatively minor and harmless flank eruptions in 1978, a more dramatic flank eruption occurred in August 1979 near Fornazzo on Etna's east flank, severely threatening this little village, which had already been in the path of menacing lava flows twice in the previous 30 years.

 

Etna went through a series of powerful summit eruptions in 1980, and a particularly large paroxysm occurred at the Northeast Crater in early February 1981. Then, in early March, the seismic stations operated on Etna by the University of Catania and the International Institute of Volcanology (a forerunner of today's INGV in Catania) started to record an increasing number of small earthquakes. On 15 March 1981, the earthquakes significantly increased in number and magnitude (reaching up to magnitude 4), and shifted from the central portion of the volcano toward its northern flank. On the following day, a warning of an imminent eruption was issued to authorities and news media.

 

The eruption broke out shortly after 13:30 h on 17 March, thirty years ago today, when dozens of small vents opened along a series of short fissures high on the northern flank of the mountain. Over the next 26-28 hours, this fissure system propagated over a full length of 8 km, cutting northwestward across Etna's flank. The sequence of events proceeded with overwhelming swiftness and violence, rarely seen before at Etna, which is generally considered a "friendly volcano". On the evening of 17 March, a particularly productive fissure segment opened between 1800 and 1400 m elevation, directly above the small hamlet of Montelaguardia, and a tremendous flood of lava burst forth, rushing down the flank consuming chestnut, poplar, oak and beech tree forests, then covering cultivated land, including extensive vineyards, and engulfing a number of farm buildings and weekend houses. The village of Montelaguardia was hastily evacuated; a few elderly people had to be rescued from isolated country homes just minutes before they would have been reached by the exceptionally fast-moving lava flow. During the night, the lava cut a number of important lifelines - roads, the Circumetnea railway, and interrupted power and telephone lines to the nearby town of Randazzo.

 

While this huge lava flow continued its work of destruction and disruption, new eruptive vents opened still further downslope, to an elevation of 1300 m, releasing small lava flows that started to flow straight into the direction of Randazzo, a peaceful town with a beautiful historical center packed with Medieval churches and other monuments. Many of the inhabitants of Randazzo only now realized that all hell had broken loose on Etna; weather conditions were not too favorable for direct observation of the eruption. Some frantically rushed to their land houses in the path of the lava flow only to find them already gone, others packed a few things and left their houses in Randazzo. Still others gathered in a procession begging the patron saint S. Giuseppe, whose feast was to be held on 19 March, to protect their town.

 

On the evening of 18 March, Etna seemed to be decided to give Randazzo the death-blow. A new fissure ripped open at only 1235-1115 m elevation, and small lava flows began to trickle into the direction of the town. For a few hours, thousands of people lived in anxiety with the whole slope of the volcano above the town seeming to be on fire. The main lava flow, which had passed only 1 km to the east of Randazzo, was approaching the bed of the Alcantara river, which had last been blocked by lava flows from Etna a few thousand years ago.

 

But early on 19 March, things seemed to calm down some - the main lava flow had significantly slowed its advance, and many of the higher eruptive vents were shutting down, whereas those on the lowest fissure segment (1235-1115 m) were showing relatively mild activity, and their lava flows were emitted at a lazy, low-rate pace, encroaching slowly on the southern margin of Randazzo. Throughout the day, the situation further relaxed, the single remaining active vents being those at the lower end of the eruptive fissure system. The lava flows fed from these vents would, at this rate of emission, not be able to reach Randazzo anytime soon.

 

The lowermost vents continued to produce small-scale Strombolian activity and minor trickles of lava until the evening of 23 March, then the eruption was over. It was estimated that between 18 and 30 million cubic meters of lava were emitted, nearly all of this volume during the first 40 hours of the eruption. At the peak of the eruption, the rates of lava emission varied between 300 and 600 cubic meters per second, which are haunting and exceptional values for Etna. Rarely has this volcano been seen erupting with such fury, although a similar eruption in November 1928 had led to the nearly complete destruction of the village of Mascali, on Etna's east-northeast flank.

 

In both cases, there were no human fatalities. In 1981, though, some elderly people were saved in extremis, furthermore large amounts of livestock (sheep, goats, cows, horses, donkeys, pigs, and chicken) died a horrible death while being unable to escape from their pens; their agonized cries were heard over kilometers during the first and most dramatic night of the disaster.

 

The photo, taken 17 years after the "Randazzo eruption", shows the ruins of a once-large country house, the "Casa Scala", just to the east of Randazzo, which was overwhelmed by the main lava flow of March 1981. The mountains in the background belong to the Peloritani mountain belt that borders Etna to the north. Photo taken with a Canon AE1, and scanned from original color slide.

 

www.ct.ingv.it/index.php?option=com_content&view=arti...

 

boris.vulcanoetna.it/ETNA_1981.html

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Taken on September 2, 2010