'Bubbly magma' can predict when volcanoes are about to erupt - even in those that have been dormant for centuries
- Campi Flegrei last erupted in 1538 but has recently shown signs of unrest
- Experts analysed tiny crystals of apatite thrown out during the eruption
- Crystals act as 'time capsules' capturing how the magma developed
- Bubbles of gas formed in the magma shortly before the eruption which suggests crystals could be used to predict future explosions
By Victoria Woollaston for MailOnline
Published: 11:02 EST, 1 February 2016
While some volcanoes can show signs of blowing days before an eruption, others explode with little warning - even those that have been dormant for decades.
Previously, it was thought such eruptions were triggered by a build-up of pressure caused by the slow accumulation of bubbly magma beneath volcanoes over hundreds of years.
But research has now shown that some eruptions may be triggered within just days as these gas bubbles form much more rapidly than first thought.
While some volcanoes show signs of blowing days before an eruption (stock image), others explode with little warning. Previously it was thought such eruptions were triggered by the slow accumulation of bubbly magma over hundreds of years. Research has now shown some may be triggered within just days of bubbles forming
Researchers, led by Mike Stock from the University of Oxford, analysed tiny crystals of a mineral called apatite thrown out during an ancient explosive eruption of Campi Flegrei.
The Campi Flegrei volcano system is near Naples, in southern Italy, and despite not erupting since 1538, it has recently shown signs of unrest.
These crystals act as 'time capsules' capturing how the magma developed and evolved.
By looking at the composition of these crystals, the team was able to show that the magma that eventually erupted had spent most of its lifetime in a bubble-free state.
It only became what the researchers described as 'gas-saturated' very shortly before the eruption took place.
Researchers, led by Mike Stock from the University of Oxford, analysed tiny crystals of a mineral called apatite thrown out during an ancient explosive eruption of Campi Flegrei (the crater of the dormant volcano of Solfatara is pictured). These crystals act as 'time capsules' capturing how the magma developed and evolved
The Campi Flegrei volcano system is near Naples, in southern Italy, and despite not erupting since 1538, it has recently shown signs of unrest. The findings suggest that rather than using seismic activity to predict when a volcano is going to blow, a better sign of might be a change in the composition of gases emitted at the surface
The findings suggest that, rather than using seismic activity and ground deformation, to predict when a volcano is going to blow, a better sign of an impending eruption might be a change in the composition of gases emitted at the surface.
For example, when the magma forms bubbles, the composition of gas at the surface should change, potentially providing an early warning sign.
THE HISTORY OF CAMPI FLEGREI
The Phlegraean Fields, or Campi Flegrei, volcano system has had a colourful history.
The Romans thought an area called Solfatara - where gas is emitted from the ground - was the home of Vulcan, the god of fire.
Meanwhile, one of the craters in the system, Lake Avernus, was referred to as the entrance to Hades in ancient mythology.
Additionally, Campi Flegrei has long been a site of geological interest.
In Charles Lyell's 1830 Principles of Geology, he identified the burrows of marine fossils at the top of the Macellum of Pozzuoli, an ancient Roman market building, concluding that the ground around Naples rises and falls over geological time.
Two eruptions have occurred at the site, one in 1158 at Solfatara and the other in 1538 that formed the Monte Nuovo cinder cone.
It is monitored by the Vesuvius Observatory.
'We have shown for the first time that processes that occur very late in magma chamber development can trigger explosive eruptions, perhaps in only a few days to months,' explained Mr Stock, from the university's Department of Earth Sciences.
'This has significant implications for the way we monitor active and dormant volcanoes, suggesting that the signals we previously thought indicative of pre-eruptive activity - such as seismic activity or ground deformation - may in fact show the extension of a dormant period between eruptions.
Professor David Pyle, also from the university, said: 'Now that we have demonstrated this approach can work on a particular volcano, and given apatite is a mineral found in many volcanic systems, it is likely to stimulate interest in other volcanoes to see whether there is a similar pattern.
'This research will also help us refine our ideas of what we want to measure in our volcanoes and how we interpret the long-term monitoring signals traditionally used by observers.'
The Campi Flegrei volcano system has had a colourful history.
The Romans thought an area called Solfatara - where gas is emitted from the ground - was the home of Vulcan, the god of fire.
Meanwhile, one of the craters in the system, Lake Avernus, was referred to as the entrance to Hades in ancient mythology.
The Phlegraean Fields, or Campi Flegrei, volcano system (illustrated) has had a colourful history. The Romans thought an area called Solfatara - where gas is emitted from the ground - was the home of Vulcan, the god of fire. One of the craters in Lake Avernus was also referred to as the entrance to Hades in ancient mythology
Additionally, Campi Flegrei has long been a site of geological interest.
In Charles Lyell's 1830 Principles of Geology, he identified the burrows of marine fossils at the top of the Macellum of Pozzuoli, an ancient Roman market building, concluding that the ground around Naples rises and falls over geological time.
Two eruptions have occurred at the site, one in 1158 at Solfatara and the other in 1538 that formed the Monte Nuovo cinder cone.
The study is published in the journal Nature Geoscience.
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