article: They are some of the most violent events on the planet, throwing out millions of tonnes of gas, ash and molten rock with each eruption. Yet the majority of the world’s volcanoes are found deep underwater where immense water pressure does weird things to the lava that bubbles out of them. Now scientists have finally been able to record one of these eruptions as it happens to discover the sound it makes - and they are surprisingly quiet for such a violent event. Scroll down to watch and listen to an underwater volcano erupting . The majority of the world’s volcanoes are found deep underwater and now scientists have been able to record one of these eruptions as it happens to discover the sound it makes. The bubbling lava erupting from the volcanic vent Hades (above) produced a distinctive acoustic signature . Rather than the explosive roar emitted by their cousins on land, underwater volcanoes give off a muted thrum instead. However, the research could allow scientists to monitor undersea volcanoes far more effectively than they have before. Volcanoes lurking hidden under the world's oceans may play a far greater role in climate change than previously though. Scientists found that underwater volcanoes, which were long assumed to ooze lava at relatively steady rates, in fact erupt in pulses. A new study has shown that these submarine eruptions follow regular cycles that can range from just a couple of weeks to 100,000 years. The researchers claim these eruptions appear to be linked to changes in the Earth's orbit that occur over time. Surprisingly the researchers also found that these eruptions also appear to be clustered during the first six months of each year. The findings may now mean that models predicting how human activity will change the climate will need to be adjusted. Volcanic eruptions are known to throw huge amounts of gas into the atmosphere, including carbon dioxide that are thought to increase global warming. However, volcanoes also release aerosol gases that are now known to reduce global warming by creating a reflective barrier against the sun. Using their unique sound signature, researchers will be able to detect different types of eruptions and record the gases being released far more accurately. Bob Dziak, an oceanographer at the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Newport, Oregon who led the research, said: ‘Detecting seafloor volcanism is important because it is a very significant process in terms of chemical impacts on the ocean and natural hazards. ‘Even though roughly 70 per cent of Earth’s volcanic activity occurs under the water, it has remained largely unobserved. ‘So, the more of these events that we can detect remotely using acoustics, the more we can understand Earth’s processes and how the planet works.’ Underwater volcanoes are known to be widespread on the floor of the world's oceans at joins in the tectonic plates. Most are located in the deep ocean, where their activity can be difficult to measure, although some in shallow water can erupt with enough lava to create new islands. Others erupt with explosive results. A recent study found that emissions from underwater volcanoes may play a far greater role in influencing the climate than had previously been believed. Rather than oozing lava at relatively steady rates, they in fact erupt in pulses that follow regular cycles ranging from just a couple of weeks to 100,000 years. In the latest study, published in the journal Geophysical Research Letters, the scientists used an underwater vehicle to visit the West Mata Volcano, 3,937 feet (1,200 metres) below the surface of the Pacific Ocean near Samoa. Eruptions from underwater volcanoes can sometimes form new islands like this one off the coast of Japan. A recent study found that emissions from underwater volcanoes may play a far greater role in influencing the climate than had previously been believed . They found different eruptions were occurring at two of the volcano’s vents – nicknamed Hades and Prometheus. Hades produced large lava bubbles that were released slowly, while Prometheus gave off explosive releases of tiny gas bubbles. They managed to film the eruptions as they happened and using hydrophones, recorded the sound they produced. They then analysed the acoustic signatures produced by each explosion, showing they are different. The graph above shows the acoustic signature as lava bubbles from Hades volcano (marked by red arrows) Scientists have struggled to study underwater volcanoes like the one above as they are hard to spot erupting. Using their unique sound signature, researchers will now be able to detect different types of eruptions and record the gases being released far more accurately . This video of Mount Tavurvur erupting on 29 August 2014 shows what volcanoes above ground sound like .
highlights: Geologists used undersea vehicles to record  two underwater volcanic vents - called Hades and Prometheus - as they erupted near Samoa .
  Scientists found the acoustic signatures of the eruptions were different .
  They hope to use sound to monitor underwater eruptions as they happen .
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