Report on Etna (Italy) — July 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 7 (July 1983)
Managing Editor: Lindsay McClelland.
Etna (Italy) Eruption ends after four months of lava extrusion
Please cite this report as:
Global Volcanism Program, 1983. Report on Etna (Italy) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 8:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198307-211060.
37.748°N, 14.999°E; summit elev. 3320 m
All times are local (unless otherwise noted)
After 131 days of activity, the eruption stopped during the morning of 6 August. The July activity was similar to that of the second half of June. The main lava channel was almost completely roofed over, but moving lava was visible through four "windows" in the channel roof. Numerous overflows from the upper "windows" produced modest lava flows of short duration during the first 10 days of July. Through the end of the month, lava emerged from scattered short-lived pseudo-vents at about 1,860-1,800 m above sea level and flowed onto the S flank lava field that has accumulated during the eruption (figure 13). These small superposed flows approached the E and W edges of the lava field; one advanced beyond the field's W margin on 13 July but stopped quickly. Efforts to contain the lava flows continued with the construction of new small embankments. None of the July flows moved below 1,600 m altitude.
Ash emissions occurred at irregular intervals from Bocca Nuova, but were not as strong as in the previous month. High-altitude winds carried ash to Catania (~30 km to the SSE) on 9, 10, and 11 July. No significant activity stoccurred from other vents.
Preliminary estimates suggest that the 131-day eruption extruded ~100 x 106 m3 of lava, at a rate of 10 m3/s. Lava flowed a maximum of 7 km from the vent, reaching 1,100 m altitude (E of Mt. Mazzo), and covered an area of ~6 km2.
Further References. Kieffer, G., 1983, L'Eruption de l'Etna commencée le 28 Mars, 1983: sa place dans l'exceptionnel cycle eruptif en cours (1971-1983): Comptes Rendus Acad. Sci. Paris, Ser. II, v. 296, p. 1689-1692.
Barberi, F., and Villari, L., eds., 1984, Special issue on Mt. Etna and its 1983 eruption: BV, v. 47, no. 2, p. 877-1177 (22 papers).
Lockwood, J.P., and Romano, R., 1985, Diversion of lava during the 1983 eruption of Mount Etna: Earthquake Information Bull., v. 17, no. 4, p. 124-133.
Geologic Background. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.
Information Contacts: R. Romano, IIV.