Ocean scientists searching for deep-sea volcanoes in the Indian Ocean have offered to answer questions from the public about their work, via the ship’s email. The scientists, on board the Royal Research Ship Charles Darwin, are posting news of their research activities on a website: ‘Fire down below – volcanoes under a tropical ocean’.

Sea of fire: sonar image of deep-sea volcano, showing the crater at its summit

The team, from Southampton Oceanography Centre, report finding an enormous expanse of lava on the seafloor. The lava flows, which are thought to be only a few years old, have spread across more than 10 kilometres, forming a giant lake spanning the boundary between the slowly separating African and Indian tectonic plates.

Dr Lindsay Parson, the expedition leader, said: “A recent volcanic eruption has spilled about two cubic kilometres of lava over an area about the size of the City of London. Previously documented examples of lava lakes like this have only reached hundreds of metres across.”

The scientists are on the last stages of a research cruise 1000 kilometres east of Mauritius. Using specialist sonar equipment they have gathered sound images to map the lake and confirmed its recent eruption with deep-sea video camera recordings. Working at depths of 3000 metres they knew immediately they were looking at a new type of lava deposit.

Dr Parson continued: “The rocks we see are glassy sheets and pillows, where molten rock at more than a 1000 Celsius has frozen in seconds as it met with sea water.” Dr Bramley Murton, in charge of sampling and rock analysis, put it into perspective: “The heat from this eruption, which appears to have occurred over a relatively short period of time, is astonishing. It would amount to some 11 terawatts, roughly the equivalent of output from 10,000 nuclear power stations.”

The expedition is focused on an area of high tectonic activity. Dr Parson explained: “We are working in the Indian Ocean, east of Mauritius, where the African and Indian crustal plates are moving apart at about 5cm a year. We are looking for hydrothermal vent sites in the newly-formed ocean crust.” These vents, or ‘black smokers’, generate valuable mineral deposits and, despite the intense heat, provide a habitat for animals that have adapted to the toxic environment. The second leg of the research cruise, which began at the end of May, aims to throw new light on these remote life forms.

Dr Parson added: “We are keen to get emails from people and answer any queries they may have about our work at sea. We are hoping this can be an interactive cruise despite the logistics involved in communicating with the ship.”

RRS Charles Darwin will be at sea until the end of June 2001.

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