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The 1972 Eruption of Kartala volcano,grande comore |
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| Authors: | B G J Upton W J Wadsworth E Latrille |
| Institution: | 1. Dept. of Geology, EH 9 3 JW, Edinburgh 2. Dept. of Geology, M 13 3 PL, Manchester 3. I.R.A.T., B.P. 31, Dzaoudzi, Comores |
| Abstract: | A summit eruption of Kartala commenced on September 8th, 1972 and finished on October 5th, 1972. In the course of this eruption, approximately 5×106 m3 of alkali olivine basalt was erupted from a N-S fissure system within and adjacent to the caldera. Aa flows were partly ponded within the caldera, almost filling the 1918 Choungou Chagnoumeni crater pit, and partly spilled NW down the flanks of the volcano. The lavas are of uniform composition, almost identical to those erupted in 1965 and closely resembling the majority of flows erupted during the last 115 years. One-atmosphere melting experiments support petrographic and chemical evidence that the lavas are coctetic, with coprecipitation of olivine, augite and plagioclase. The lavas were crupted at, or close to, their liquidus temperature, determined at approximately 1170°C. Whereas eruptions of Kartala in the nineteenth century were distributed widely along a fissure system approximately 45 km long by 7 km wide, the eruptions since 1918 have been confined to the vicinity of the summit caldera. |
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