NQT Presentation

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Ice on the Land Podcast

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Ice on the Land Podcast

James Cameron back on surface after deepest ocean dive

Hollywood director James Cameron has returned to the surface after plunging nearly 11km (seven miles) down to the deepest place in the ocean, the Mariana Trench in the western Pacific.

This is only the second manned expedition to the ocean's deepest depths - the first took place in 1960 when US Navy Lt Don Walsh and Swiss oceanographer Jacques Piccard spent about 20 minutes on the ocean floor in a bathyscaphe called the Trieste.

While places like the Mariana Trench were once thought to be of little interest, there has been a recent resurgence of scientific interest in the deep.

Scientists are finding life that can resist the colossal pressures, from deep-sea fish to shrimp-like scavengers called amphipods, some of which can reach 30cm (1ft) long.

They are also trying to understand the role that deep seas trenches play in earthquakes - these cracks in the sea floor are formed at the boundary of two tectonic plates and some believe the push and pull taking place deep underwater could be the cause of major earthquakes, such as the 2011 quake that resulted in such devastation in Japan.

See the picures by clicking here

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Mega volcanoes 'may be predicted'

Despite what I've said in class....

The eruption of some of the largest volcanoes on the planet could be predicted several decades before the event, according to researchers.

Analysis of rock crystals from the Greek island of Santorini suggests eruptions are preceded by a fast build-up of magma underground, which might be detected using modern instrumentation.
Such volcanoes can produce enough ash and gas to temporarily change the global climate.

Volcanologists refer to history's largest volcanoes as "caldera-forming eruptions", as the magma ejected is so voluminous that it leaves a massive depression on the Earth's surface and a crater-like structure known as a caldera.

The largest of these volcanoes have been dubbed "supervolcanoes" and their eruptions can trigger devastation with global impacts.

Such volcanoes can lie dormant for hundreds of thousands of years before blowing. But while researchers believe seismic data and other readings would give us a few month's notice of such an eruption, the new study suggests we might anticipate these events much earlier.

"When volcanoes awaken and when the magma starts to ascend to the surface, cracking rock as it does, it sends out signals," Prof Tim Druitt of France's Blaise Pascal University and lead researcher told BBC News.
"You get seismic signals, you get deformation of the surface, increasing gas emission at the surface - and this can be detected.

"The question we're addressing here is what's going on at depth prior to these big eruptions. The classical view was that during long repose periods over thousands of years, magma slowly accumulates a few kilometres below the volcano and finally it blows.

The Greek island of Santorini is actually the remains of a massive volcanic eruption

"What we're finding is that there's an acceleration phase of magma build-up on a time scale of a few decades, and that's surprisingly short given the thousands of years of repose that have preceded that eruption."

The evidence comes from analysis of crystals in pumice rock from the Santorini site, which the researchers in France, Switzerland and Singapore analysed using modern instrumentation including electron and ion microprobes.

"The changes in composition of the crystals with time provide little histories of how the magma itself has evolved," said Prof Druitt.

"What we found was that all the crystals in the magma grew within a few decades of the eruption."
Early warning

Caldera-forming eruption sites can be found all over the world, although it is believed that all are currently dormant. They include sites in Yellowstone National Park in the United States, Campi Flegrei in Italy and Santorini and its accompanying islands.

The eruption at the latter site over 3,600 years ago is called the "Minoan" eruption as it occurred at the height of the Minoan civilisation on the nearby island of Crete and was once thought to have caused its collapse, although that is now a moot point.

Predicting such events years rather than months before they happen could prove vital, says Prof Druitt.
"What we're saying is that all caldera volcanoes, even those in remote regions of the globe, should be monitored using highly sensitive modern instruments in order to pick up these deep signals which may suggest reactivation," he said.

"If you had a big eruption of this sort, let's say in the middle of Europe today, the effects would be enormous and a few months might not be enough to get your act together."

A volcanic "caldera" like this one on the Galapagos Islands can change the global climate when they erupt

Commenting on the paper, Prof David Pyle, a volcanologist from Oxford University said: "This new work on Santorini sheds new light on what happens in the lead-up to the rare catastrophic eruptions, like the Bronze Age 'Minoan' eruption, which happen every 20,000 years or so.

"The new evidence from mineral grains appears to strengthen the idea, which has been developing in recent years, that large magma systems appear to awaken from long periods of repose only shortly (months, years or decades) prior to eruption.

"That is, the magma which eventually erupts appears to rise into position, in the top few kilometres of the crust, only a short time before the eruption begins."

However, he said the next problem was to try to understand what was causing this accelerated build up of magma.

"The challenge for volcanologists is to understand what it is that causes these bursts of melt movement; to understand where the melts have come from, and to be able to recognise their signals before an eruption begins."

Cliff Collapse

Geologist Richard Hocking, who filmed a massive cliff fall in Cornwall, says it was the most exciting thing that he has ever seen.

Thousands of tonnes of rock fell into the sea at North Cliffs near Hayle two weeks ago - just days after part of the coastal footpath was diverted.

Mr Hocking put the video on YouTube - hoping to attract comments from other geologists - but it has since been viewed more than 750,000 times and copied and shown around the world.

Click here to watch the video

What's the Coastal Landform?

Can you explain how this this coastal landform was created?

Glacier meltwater threatens villages

A glacier in Nepal is melting fast and creating a huge lake. The lake has the potential to be 6km long, 1 km wide and 100m deep and is sitting behind a mound of terminal moraine. The worry is that if the water breaks through the moraine the flood would sweep down the vally and destroy Villages and the people who live there.

Read the full story here.