An ash-filled sky

Image: NASA/MODIS Rapid Response Team

The plume of volcanic ash that is responsible for grounding planes across northern Europe traces a dirty smear across the Norwegian Sea in this photo snapped by NASA’s TERRA satellite.

A volcano beneath the Eyjafjallajoekull glacier on the south coast of Iceland is blasting ash up to 11 kilometres into the atmosphere. At this altitude, strong winds are blowing the plume of ash south-eastwards, towards the UK and mainland Europe.

But why is volcanic ash such a problem for aircraft? The ash contains tiny particles of volcanic glass, which can be sucked into jet engines. Jet engines operate at temperatures high enough to melt the glass particles, which causes sheets of glass to form, blocking fuel nozzles and other sensitive components.

The tiny glass shards are also abrasive, and they’ll quickly damage cockpit windows – reducing visibility. The risk to aircraft from volcanic ash is so great that it is far safer to cancel all flights until the ash plume disperses. As the volcano is still erupting, this may take some time!

The volcano near Eyjafjallajoekull first erupted on the 20th March 2010, following months of small earthquakes, and caused Icelandic authorities to evacuate around500 people. The second eruption on the 14th April was ten to twenty times larger than the first because this time the magma came into contact with glacial ice, causing a powerful explosion, which threw ash high into the atmosphere.

While a potential hazard for aircraft, the ash probably isn’t a major health hazard for the UK population. The ash plume is so high that ash particles aren’t expected to reach the ground in the UK, according to a statement from the Health Protection Agency. So the only thing you need to look out for are the predicted beautiful red sunsets!

‘Fossilised’ supervolcano reveals hidden secrets

Scientists from the USA and Italy have found the fossilised form of a long-buried supervolcano preserved in rocks in the Sesia valley, Italy. An unusual contortion of the Earth’s crust exposed the fossil supervolcano, allowing scientists to see for the first time the hidden plumbing that feeds volcanic eruptions.

Inside the caldera at Lake Toba, Indonesia. It looks peaceful from here, but what's happening deep below? Image: Wikimedia/Tbachner

The supervolcano in Sesia valley was revealed by the movement of the Earth’s tectonic plates, which make up the crust of our planet. As the African plate drifted northwards towards Europe, a piece of crust in modern-day Italy was pushed upwards, bringing the fossilised volcano to the surface. It exposed not only the 13-kilometre-wide crater, or caldera, of the volcano, but the 25-kilometre-deep plumbing system beneath it. The tracks left by magma forcing its way to the surface are clearly visible in the rocks, and gave the scientists a unique opportunity to see “inside” one of nature’s most powerful forces.

Supervolcanos, such as the one buried beneath Yellowstone National Park in the USA, have the potential to cause global catastrophe. Supervolcanic eruptions are caused by the explosive eruption of gas from molten rock oozing towards the surface, which throws thousands of cubic metres of rock and ash into the air. Our ancestors witnessed one such event 74,000 years ago when a supervolcano erupted under Lake Toba, in Indonesia. The ash and sulphur dioxide it released caused the global temperatures to drop by 3 – 5^oC, wiping out plants and the animals that depended on them. Research suggests 60% of the people alive at the time were killed.

The new discovery in Sesia valley will help scientists to understand what drives the devastating eruption of a supervolcano, and perhaps develop ways to predict when we may next see such an eruption occur.

Paper reference: doi: 10.1130/G30003A.1

Do volcanoes cause mass extinctions?

For the first time, scientists can say with some certainty that a mass extinction immediately followed a series of huge volcanic eruptions. The findings support the idea that such volcanic activity could be responsible for many of the mass extinctions we can see in the fossil record.

The latest study, conducted by UK and Chinese scientists, has shown that volcanic eruptions which buried the Emeishan province of China under layers of basalt rock 260 million years ago coincided with the death of many sea-dwelling species.

The volcanic eruptions covered an ancient seabed with a layer of volcanic rock, clearly marking the exact time of the eruptions in the geological record. By looking at fossils trapped in rocks created before and after the volcanic eruptions, the scientists showed that many species went extinct around the same time. Although it might just be a coincidence, the timing of the eruptions and the extinction means they could be connected.

Suspiciously, several other mass extinctions also overlap with periods of substantial volcanic activity. In fact, two of the most well-known mass extinctions have been linked with the creation of areas of volcanic rock resulting from large eruptions. 65 million years ago the dinosaurs were wiped out, either by a meteorite or by the volcanic eruptions that created the Deccan Traps in India. The end-Permian extinction 250 million years ago, which killed over 96% of all of marine species alive at the time, is associated with the violent volcanic creation of the Siberian Traps.

This latest find might just be a coincidence, but it might also provide an interesting hint that mighty volcanic eruptions played a central role in some of the most significant events ever to occur to life on Earth.