Undersea Volcano

A volcano the size of Wellington Harbour is one of the finds of a research trip to the farthest reaches of New Zealand’s marine real estate.

For the past three weeks, 27 scientists on the ship have been mapping, probing and sampling the northernmost section of the Kermadec Arc, which stretches from the Bay of Plenty to Tonga.

They discovered and captured three-dimensional images of previously unknown volcanoes, including one measuring eight kilometres by five kilometres which is about the size of Wellington Harbour.

According to the expedition’s weblog, the volcano has been named, temporarily, the Monowai, and despite an earlier survey coming close to the area in 1998, no one knew it was there. Finding it, says the trip’s leader Dr Cornel de Ronde of Geological and Nuclear Sciences, was an absolute surprise. “It’d be like saying, ‘Oh look at Ruapehu, isn’t that lovely?’ then turning behind you and seeing the Grand Canyon! This was completely and utterly an unknown. Truly a new discovery,” de Ronde is quoted as saying on the expedition’s weblog.

Throughout the voyage, and particularly when volcanoes were discovered, Tangaroa stopped and lowered “sniffer” equipment to collect information about the volcanic plumes rising from the submarine volcanoes and hydrothermal vents.

The plumes are rich in dissolved iron, manganese, and copper, with lesser concentrations of zinc, lead and gold. As well as depositing metallic minerals on the seafloor, they are an important source of trace elements in the world’s oceans.

In addition, apart from minerals, the volcanoes produce large amounts of methane, hydrogen sulphide, and carbon dioxide gases. One of the aims of the voyage was to set in place equipment that will measure the volumes of gases being produced from the seafloor during the next six months.

“Much of what we’ve been doing is ground-breaking science. Others will follow in our footsteps and build on the platforms we’ve set up,” Dr de Ronde said in a statement on his return to New Zealand after the almost month-long voyage.

Scientists believe that life on earth may have begun next to volcanic seafloor hotsprings such as those that have been probed during the past three weeks. The organisms that live in this hostile environment may have potential applications in areas such as industry and pharmaceuticals.

Parts of the voyage have relevance to safety as well as science, according to NIWA scientist and co-leader of the voyage Ian Wright.

“Five or ten years ago people didn’t believe you could get these caldera volcanoes in submarine settings. The conventional wisdom of the 1970s was that you couldn’t have explosive submarine volcanic eruptions, and if you did they were very shallow. However, there’s been a major change in our thinking,” Dr Wright said…

“What we’re trying to do is gain an understanding of when eruptions occurred so that we can have some sense about tsunami generation. These submarine volcanoes are potential sources of tsunami.”

With much of New Zealand’s coastline exposed to the Pacific Ocean, knowing more about how tsunami are triggered is likely to have potential benefits.

The voyage was the third in a series of expeditions that started in 1999, aimed at finding out as much as possible about the 2500 kilometres of volcanic seafloor between New Zealand and Tonga.

The voyages are a collaboration involving two New Zealand public research institutes, the Institute of Geological and Nuclear Sciences and the National Institute of Water and Atmospheric Research, and the United States’ National Oceanic and Atmospheric Administration and the Australian National University.

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