REPORTAGE FOR BBC NEWS " ETNA ERUPTION" Dop G.Castiglione

ERUZIONE ETNA 1990 ZAFFERANA ETNEA IN PERICOLO , OPERAZIONI CONGIUNTE TRA U S NAVY ED GENIERI ITALIANI .GIRATO PER LA BBC NEWS DA ME. During the 1992 eruption of Etna earthworks are used to save the town of Zafferana Etnea from lava flows. In January 1992 an earth barrier 234 m long and 21 m high was constructed. The embankment contained lava for about a month and was overflowed on 9th April 1992. Three additional smaller earthen barriers (length: 90-160 m; height: 6-12 m ) were built in April to gain time while the lava front was descending towards Zafferana from the overflowed first embankment. The main intervention point was located in Valle del Bove at an elevation of 2000 m, at 8 km from Zafferana. Initial interventions called for attempts at plugging a tunnel by dumping into it linked concrete blocks, hedgehogs and blasted portions of the solid levee. Each intervention caused the partial obstruction of the tunneled channel, which determined major increases of lava overflow in Valle del Bove and the consequent halt of the most advanced fronts. The intervention gave at the most two weeks of respite, before new lava fronts approached the outskirts of Zafferana. The final successful intervention was carried out on May 27-29, 1992. An artificial channel was dug departing from the natural one. The solid separation levee was thinned to 3 m and blasted by 7000 kg of explosives. After the explosion, 2/3 of the lava flowed spontaneously in the artificial channel. As a consequence of the intervention the active natural lava front, that on May 27 was only 850 m from Zafferana stopped.