Scientific Expedition to Barren Island
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A team of scientists from India and Italy carried out detailed geological, volcanological, geochemical and geothermal investigations in Barren Island between the 3rd and 6th of February, 2003. The scientific team led by D. Chandrasekharam, Department of Earth Sciences, Indian Institute of Technology, Bombay, India, consists of scientists from Italy - Piero Manetti, Director, Italian National Science Council - Institute of Geosciences and Earth Resources (CNR-IGG) (CNR), Orlando Vaselli, Department of Earth Sciences, University of Florence, Bruno Capaccioni, Institute of Volcanology and Geochemistry, Urbino University, and Mohammad Ayaz Alam, Research Scholar, Department of Earth Sciences, Indian Institute of Technology, Bombay, India This is the first scientific team ever camped in this uninhabited volcanic island. Indian Coast Guard vessel CGS Lakshmi Bai, commanded by Commander P. K. Mishra helped to ferry the team from Port Blair to Barren Island. The journey takes about five to six hours. |
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Barren Island is the only active volcano in the Indian Subcontinent, located 135 km east of Port Blair, in east Andaman Sea and is a part of Andaman Nicobar chain of islands in the Indian Ocean. The Barren Island lies on the inner arc extending between Sumatra and Myanmar. The volcano consists of a caldera open towards the west, with a central polygenetic vent enclosing at least 5 nested tuff cones. Two spatter cones, one on the western flank of the central cone and the other on the southeastern flank of the central cone exist . 
The last volcanic activity in the island occurred in 1994-95. However, Indian Coast Guard informed the team of renewed activity (strong gas and, perhaps, lava emissions) in January 2000. According to the present observation, the structure of the central polygenetic cinder cone appears to have been developed during the 1994-95 activity, which left, as mentioned above, two visible spatter cones on its southern-eastern and western flanks. From these vents two lava flows (aa-type) were outpoured, both reaching the sea, during two distinct eruptive phases, separated by an ash-fallout. On the 5th of February we climbed the summit of the central cinder cone that shows strongly fumarolized (but not presently active) areas. The ascent to the crater was relatively difficult since the material is loose cinder. Neither magma and nor gas emissions were observed at the bottom of the different cones. From the middle to the upper part of the western cone, the ground temperature is relatively high (>40 °C) and steaming grounds are clearly visible at different sites. The fumarolic activity, with temperature up to 101 °C, is mainly concentrated in the upper-inner part of the southern-western cone. Blue colour fumes (indicative of the presence of SO2) and smells of acid gases such HCl were not recorded. By a volcanological point of view, the pre-caldera deposits are characterised by the presence of more than five lava flows (prehistoric?) separated by scoria fall beds and minor ash tuff and cinder deposits. The lava flows vary in thickness from 2 to 3 metres, while the other volcanic materials vary in thickness from one to four metres. These flows can be clearly seen towards the northern part of the main caldera. Towards the southeastern part of the inner caldera a 5 m wide, NNE-SSW trending dyke is observed. This dyke is fine to medium grained and contains buff coloured olivine, green pyroxene and plagioclase phenocrysts. The northern and north-western part of the caldera has been mantled by a ~50 m thick monotonous sequence of breccias and tuff representing sin/post-caldera phreatic and hydromagmatic activities, whereas the products of a small littoral cone occur mainly towards the western side close to the landing site. The flows of the main caldera are highly porphyritic with phenocrysts of green pyroxene (~3 cm) and plagioclase feldspars. Several steam vents can be seen within the 1995 lava flows . 
The outer and part of the inner caldera contains thick vegetation, which escaped the fury of the recent eruptions. Feral goats and rats dominate the island. Large number of rats lives in the island and become a menace at night. There have been reports on the life of the feral goat of this island. Earlier reports indicate that these goats adapted to a different kind of life and drink seawater to meet their water requirement. But during the present expedition two fresh water springs have been discovered towards the southeastern part of the caldera. This is possibly the main water source for the goats living in this island. The water from the springs is potable and samples have been collected for further investigation. Profile: Note:
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