Tag Archives: underwater volcano

Researchres found a chain of underwater volcanoes 400 kilometers (250 miles) east of Tasmania. Credit: CSIRO.

Underwater volcano found off Australian coast may act as superhighway for whales

Researchres found a chain of underwater volcanoes 400 kilometers (250 miles) east of Tasmania. Credit: CSIRO.

Researchers found a chain of underwater volcanoes 400 kilometers (250 miles) east of Tasmania. Credit: CSIRO.

Completely by chance, researchers have come across a striking underwater chain of volcanoes rising amid the deep ocean. The ancient, extinct volcanoes tower 3 kilometers (1.9 miles) above the ocean floor, but, despite their massive size, they’ve stayed concealed from our prying eyes due to a 2 km-thick (1.2-mile) layer of water.

Researchers think that this diverse landscape is a perfect breeding ground for all sorts of lifeforms, likely hosting an array of yet-undescribed new species. The seamounts may also act as ‘signposts’ on the migratory highway for humpback whales that move from their winter breeding to summer feeding grounds.

These seamounts are likely the geological remnants of the ancient split off between Australia, Australia, and Tasmania, which took place about 30 million years ago.

Australian researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian National University were responsible for the discovery. The team’s research vessel Investigator was busy monitoring nutrient and phytoplankton levels in the East Australian Current when the ship’s sonar detected unusual contours beneath the ocean, 250 miles (400 kilometers) east of Tasmania.

It didn’t take long for the researchers to realize that the submerged mountains were brimming with life. Right as the ship was sailing above the uncharted terrain, the researchers detected a huge spike in phytoplankton activity — the bottom of the food chain that ensures the livelihoods of

“While we were over the chain of seamounts, the ship was visited by large numbers of humpback and long-finned pilot whales,” said Dr. Eric Woehler from BirdLife Tasmania, who was on the Investigator with a team surveying seabirds and marine mammals.

“We estimated that at least 28 individual humpback whales visited us on one day, followed by a pod of 60-80 long-finned pilot whales the next.

“We also saw large numbers of seabirds in the area including four species of albatross and four species of petrel.”

Credit: Wikimedia Commons.

Credit: Wikimedia Commons.

Investigator will return to the region for two more research voyages in November and December. During these times, they will use deep water cameras to film marine life living on the seamounts. They will also collect rock samples in order to gain a better understanding of the region’s geological origin and evolution.

“We expect that these seamounts will be a biological hotspot year round, and the summer visit will give us another opportunity to uncover the mysteries of the marine life they support,” said Dr. Woehler.

Kick-‘em-Jenny: Scientists get rare chance to study volcano as it’s erupting

A team of British researchers chanced upon something unexpected as they were carrying out a marine survey: an erupting underwater volcano. Their new study helps shed new light on underwater volcanoes, which are notoriously difficult to study.

Bathymetric map from the survey. Image credits: Imperial College London

Aboard the research ship R.R.S. James Cook, scientists from several UK universities, in collaboration with The University of the West Indies Seismic Research Centre, were collecting ocean-bottom seismometers, as part of a larger research project — when they got an alarm message. The culprit was an underwater volcano called ‘Kick ’em Jenny’, one of the Caribbean’s most active volcanoes.

Normally, when you’d hear that a volcano was erupting nearby, you’d want to get as far away as possible from it. But when you’re an Earth scientist aboard a research vessel, you might want to do the opposite: get as close as is safely possible.

Direct observations of submarine eruptions are extremely rare, but since the scientists were already nearby, they were able to get close enough to the volcano to record the immediate aftermath of the eruption, including the gas coming out of the central cone.

Survey of the cone with gas venting in April 2017. Image credits: Imperial College London.

It wasn’t the first time the volcano had been surveyed, but it was the first time one of its eruptions was imaged directly. Lead author and PhD student Robert Allen, from the Department of Earth Science & Engineering at Imperial College in London, said:

“There are surveys of the Kick-‘em-Jenny area going back 30 years, but our survey in April 2017 is unique in that it immediately followed an eruption. This gave us unprecedented data on what this volcanic activity actually looks like, rather than relying on interpreting seismic signals.”

The volcano has erupted on at least twelve occasions between 1939 and 2001 and it’s still quite active. The team found that Kick-’em-Jenny (a reference to the rough waters in the area) goes through a cycle of lava ‘dome’ growth, followed by landslides which trigger a collapse. A similar cycle has been observed with other volcanoes in the Caribbean, for instance on the island of Montserrat.

If a volcano as active as Kick-‘em-Jenny was on land, it would have been studied and monitored in great detail. But since it’s underwater, and thus both less dangerous and more difficult to study, geologists know far less about it than they’d like to. However, this study can also improve monitoring techniques to be used in the future. Co-author Dr. Jenny Collier, from the Department of Earth Science & Engineering at Imperial, concludes:

“Kick-‘em-Jenny is a very active volcano but because it is submarine is less well studied than other volcanoes in the Caribbean. Our research shows that whilst it has quite regular cycles, it is on a relatively small scale, which will help inform future monitoring strategies.”

The study has been published today in Geochemistry, Geophysics, Geosystems.

Seafloor sensors provide unprecedented view into underwater eruption

A seafloor observatory has gathered a trove of data from the 2015 eruption of Axial Volcano, some 480 km off the coast of Oregon, allowing researchers to “see” the eruption in unprecedented detail.

Image credits: University of Washington.

Whenever a volcano erupts, it rumbles and shakes, similar to an earthquake in some ways. It sends ripples (seismic waves) in all directions, which can be picked up by specialized equipment. By then studying these seismic waves, we can tell a lot about the geologic setting of the area, something particularly interesting for the Axial Volcano, where two tectonic plates are moving apart. Basically, geologists believe that by studying this volcano they can get a better understanding of the volcanic activity around mid-oceanic ridges.

“The new network allowed us to see in incredible detail where the faults are, and which were active during the eruption,” said lead author William Wilcock, a UW professor of oceanography. The new paper in Science is one of three studies published together that provide the first formal analyses of the seismic vibrations, seafloor movements and rock created during an April 2015 eruption off the Oregon coast. “We have a new understanding of the behavior of caldera dynamics that can be applied to other volcanoes all over the world.”

The Axial Volcano is a particularly complex case. It is part of the Axial Seamount in the Juan de Fuca Ridge, located both at the center of both a geological hotspot and a mid-ocean ridge. This means that it is “fed” by underlying mantle that is anomalously hot compared with the surrounding mantle and also by magma exposed by the tectonic spreading – two unrelated phenomena which make everything more difficult to understand.

A seismic instrument (long black cylinder, right) installed in 2013 on a level triangular metal plate on the seafloor atop Axial Volcano. The green plate holds electronics that communicate between the instrument and the orange cable sending data back to shore as part of the National Science Foundation’s Ocean Observatories Initiative.
Credit: University of Washington/OOI-NSF/CSSF-ROPOS

The Axial Seamount is the most active volcanic site in the North Pacific. Study of magnetic delineations along the seamount have modeled the ridge’s history up to 30 million years ago. The place is marked by an unusually rectangular caldera, with several dome-like structures. An advantage of studying this particular volcano is that the location of the magma chamber is well known, and Axial is quite active.

“Axial volcano has had at least three eruptions, that we know of, over the past 20 years,” said Rick Murray, director of the NSF’s Division of Ocean Sciences, which also funded the research. “Instruments used by Ocean Observatories Initiative scientists are giving us new opportunities to understand the inner workings of this volcano, and of the mechanisms that trigger volcanic eruptions in many environments.

“The information will help us predict the behavior of active volcanoes around the globe,” Murray said.

Most people don’t know, but the vast majority of volcanic activity takes place underwater – which makes sense when you consider that most of the Earth’s surface is covered in water, and the vast majority of volcanoes take shape at the edge of oceanic tectonic plates.

Journal Reference: W. S. D. Wilcock, M. Tolstoy, F. Waldhauser, C. Garcia, Y. J. Tan, D. R. Bohnenstiehl, J. Caplan-Auerbach, R. P. Dziak, A. F. Arnulf, M. E. Mann. Seismic constraints on caldera dynamics from the 2015 Axial Seamount eruption. Science, 2016; 354 (6318): 1395 DOI: 10.1126/science.aah5563

10,000 year old underwater forest discovered

Divers off the coast of Norfolk have discovered a submerged prehistoric forest, hidden underwater for 10,000 years. The forest was part of Doggerland – a land area which connected Germany and Great Britain up to 8000 years ago.

This is a forgotten part of Europe, hidden under 200 meters of water. Divers discovered it after a winter storm shifted thousands of tonnes of sand beneath the ocean. Research has already been conducted on wood from the forest, and scientists dated it at 10,000 years. Professor Julian Andrews from the University of East Anglia who conducted the study, called the discovery “very exciting”.

“I couldn’t believe what I was seeing at first. The sea was quite rough by the shore so I decided to dive slightly further out and after swimming over 300 metres of sand I found a long blackened ridge. When I looked more closely I realised it was wood and when I swam further along I started finding whole tree trunks with branches on top, which looked like they had been felled”, said Dawn Watson, who discovered the forest.

Doggerland was a former landmass in the southern North Sea that connected Great Britain to mainland Europe during and after the last Ice Age until about 6,500 or 6,200 BC. Gradually raising sea levels slowly flooded Doggerland. Archaeologists have exhibited interest in the area for more than a century, but interest intensified in 1931 when a commercial trawler dragged up a barbed antler point that dated to a time when the area was tundra. Since then, archaeologists have unearthed remains of mammoth, lion and other land animals, and small numbers of prehistoric tools and weapons. Geologist Martin Warren said Doggerland was part of a “country Europe forgot”.

Image via Wiki Commons.

As the Doggerland tundra became more and more flooded, it eventually turned into a marshland, forcing populations to slowly retreat either towards the west (UK) or the east (continental Europe). But geological studies show that a five meter tsunami likely wiped out remaining populations at one point.

Initially, this forest was discovered by Sea Search diver Dawn Watson, who came across “an enormous wave of black stuff. It wasn’t until later that he discovered he had stumbled upon an ancient oak forest.

‘It was amazing to find and to think the trees had been lying there completely undiscovered for thousands of years. You certainly don’t expect to go out for a quick dive and find a forest’, Watson said.

She uns the Marine Conservation Society’s survey project, Seasearch in East Anglia with partner Rob Spray.

“At one time it would have been a full-blown Tolkein-style forest, stretching for hundreds of miles,’ added Mr Spray, who has begun surveying the forest with his partner. It would have grown and grown and in those days there would have been no one to fell it so the forest would have been massive. It would have looked like a scene from the Hobbit or Lord of the Rings, which is something we don’t get in this country anymore. Geologists are very excited about it, it was a really miraculous find.”

Underwater volcanoes beneath the Antarctic seas. The peak in the foreground is thought to be the most active, with eruptions in the past few years. (c) British Antarctic Survey

Hugely tall underwater volcanos discovered

In the first ever-survey of its kind, geologists have managed to discover a chain of massive underwater volcanoes, some as tall as 2 miles, underneath the Antarctic waters near the South Sandwich Islands in the remote Atlantic Ocean.

The South Sandwich Islands have always been known for their evident volcanic activity, ever since their discovery by famous explorer Captain Cook in 1775. What happens beneath the islands however remained more or less ignored, until recently when scientists mapped in great detail the area of the seafloor around these islands.

Underwater volcanoes beneath the Antarctic seas. The peak in the foreground is thought to be the most active, with eruptions in the past few years. (c) British Antarctic Survey

Underwater volcanoes beneath the Antarctic seas. The peak in the foreground is thought to be the most active, with eruptions in the past few years. (c) British Antarctic Survey

Scientists used sonar scanners to trace each shape and slope of the volcanoes, which fed them back some incredible data – 12 new undersea volcanoes, some topping even two miles. Some are still active, while others have been found collapsed in craters as large as 3 miles.

The volcanoes came as a consequences, scientists claim, of the tectonic dance between the South American continental plate sliding under the South Sandwich plate to the east. Water gets slipped beneath one of the plates and deep into the interior of the earth, from where it escapes upward, springing a molten rock eruption along the way.

Underwater volcanoes form parallel to the plane lines and as they steadily build up, they form new crust which will eventually someday after millions of year link with a continent. Scientists hope to learn more by studying the process in greater detail, and gain a greater grasp upon the formation of continents.

“We have GPS data to show that the South Sandwich Islands are moving east very fast indeed with respect to Africa,” Ian Dalziel of the University of Texas at Austin said. “It’s a very active system.”

Researchers warn however that underwater volcanoes could cause highly damaging tsunamis, since such volcanoes often have unstable slopes.

“This is quite well known,” Phil Leats of the British Antarctic Survey who led the new efforts said “Clearly this has happened in this area. We can see the scars. We can see the quite large slump deposits, which must have caused quite large tsunamis, so clearly it’s an area where this kind of hazard does exist.”

The survey was made by the  British Antarctic Survey.

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