TO ANCIENT Romans the Phlegraean Fields hosted the entrance to Hades. In modern times it is better known as the site of a 鈥渟upercolossal鈥� volcanic eruption 39,000 years ago.
Will we see the next disaster coming? That鈥檚 one of the questions an ambitious drilling project hopes to answer by sinking boreholes into Campi Flegrei, as the giant collapsed volcanic crater is now called. Starting as early as next month, the Campi Flegrei Deep Drilling Project is planning to drill seven holes in the region (see map).
Though the researchers on this particular project point out that any risk is small, it will begin amid debate about whether such endeavours are safe, given the unknowns of a volcano鈥檚 interior. A few say drilling might even trigger a major eruption.
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Though the caldera has no visible volcanic cone, it dwarfs nearby Vesuvius. 鈥淢ost of the metropolitan area of Naples is located within the caldera,鈥� says Giuseppe De Natale of the National Institute of Geophysics and Volcanology鈥檚 (INGV) , who is leading the project.
鈥淭he volcano has no visible cone but it dwarfs Vesuvius, and most of Naples is in its caldera鈥�
鈥淎 major eruption, like the one 39,000 years ago, would leave large parts of Europe buried under a thick layer of ash,鈥� says Agust Gudmundsson of the Royal Holloway University of London, one of the researchers involved in the drilling project. Since then, smaller eruptions have occurred every few centuries.
According to a study of the region by Roberto Isaia of the INGV and colleagues, Campi Flegrei is 鈥渙ne of the highest risk volcanic areas on Earth鈥� and may now be primed for a blast. Isaia and colleagues found deposits from an intense period of eruptions around 4000 years ago. Before the eruptions the Earth鈥檚 crust rose by several metres all across the caldera. Worryingly, crustal uplift is exactly what has happened recently. Since the late 1960s, the port of Pozzuoli near the caldera鈥檚 centre has risen by around 3 metres. Hazard planners should prepare for eruptions in decades or less, Isaia concludes (Geophysical Research Letters, in press).
The drilling could reveal fracture zones and pockets of magma whose location can usually only be inferred. This could show exactly where magma might ascend and collect prior to an eruption. Meanwhile, rock samples could be tested under high stresses in the lab to help model the ground deformation prior to eruption. De Natale told 快猫短视频 that the project 鈥� which is under the auspices of the International Continental Scientific Drilling Program and the Integrated Ocean Drilling Program 鈥� will start in December or January.
Several incidents have plagued similar projects. In June, the (IDDP), which aims to tap geothermal energy from hot magma, had to be stopped. At 2104 metres down, magma streamed into the borehole, causing a small explosion as the drilling fluid vaporised. That project is on hold, though it will start again in 2011 with a new borehole, says Gu冒mundur 脫mar Fri冒leifsson of the IDDP. And in 2005, researchers working on a drilling project in Hawaii got a fright when magma hotter than 1000 掳C leaked into the borehole.
鈥淯nder unfavourable conditions, contact of the drilling fluid with magma could be very dangerous,鈥� says Ralf B眉ttner, a volcanologist at the University of W眉rzburg in Germany. 鈥淚t is even theoretically conceivable that, ultimately, a major eruption could result.鈥�
Though he does not single out the Campi Flegrei project, he warns that not enough is known about what happens in the guts of a volcano to justify drilling. 鈥淜nowledge about the viscosity and processes of gases in magma is very limited.鈥� What we do know is based on extremely small samples, which makes it difficult to extrapolate the results to larger masses, he says. So volcanic drilling projects are often based on 鈥渨ishful thinking rather than on hard facts鈥�, he adds.
The greatest risk would be if the drilling accidentally pierced a silica-rich magma chamber under high pressure, releasing trapped gases, saysVolker Dietrich, also of the University of W眉rzburg. 鈥淭he threat of explosion is extremely high. Theoretically, any type of eruption could be triggered,鈥� says Dietrich. 鈥淚n some circumstances, the risk is of a total disaster.鈥�
Researchers on the Campi Flegrei project accept that there are some small risks, but say prior safety assessments found that triggering a major eruption is unlikely. Christopher Kilburn of University College London, one of the lead scientists, points out that a pressure release would need to occur over a significant portion of a magma reservoir to trigger an eruption. This is 鈥渦nlikely to be satisfied by a small borehole, unless, perhaps, the magma was about to erupt anyway,鈥� he explains. Bernd Zimanowski at the University of W眉rzburg agrees. He says that drilling into 鈥渁 tough magma chamber is no different from pricking some extremely tough cookie dough鈥�.
In any case, the Campi Flegrei drilling is unlikely to hit magma. Boreholes are expected to reach a maximum depth of 4 kilometres, around half the depth of any known reservoirs, according to J枚rg Erzinger of the German Research Centre for Geosciences in Potsdam (GFZ). Even if magma flows into a borehole, Ulrich Harms, another GFZ scientist, argues it would not necessarily be dangerous. 鈥淪ituations like that provide exceptional insights,鈥� Harms says.
