Amongst the volcanoes of the world there exist a number of very large ones, known as supervolcanoes. These volcanoes are generally calderas, which are created when a depression forms after a large explosion. As such these volcanoes often form lakes surrounded by fertile soil, thus being a nice place to live, well known examples include Yellowstone, USA, Lake Taupo, New Zealand and Krakatoa, Indonesia – site of the largest eruption in recorded human history (1883).
One of these calderas is Campi Flegrei,which is located in Naples, Italy;
it had its last major eruption about 40000 years ago but also had a minor eruption in 1538 and still has active steam vents. Since 2009 scientists from Italy and Germany have been attempting to get permission to drill up 4km into the caldera, in the hope of gaining more information about how movement within the magma chamber affects the rise and fall of the surface within the caldera, and if this is linked to eruptions.
Opponents of the proposal are worried that it could trigger the release of supercritical fluids from around 3km in depth, as well as seismic activity, though they have not suggested that an eruption could be triggered. Last week the Mayor of Naples approved the drilling of a pilot hole 500 m in depth, with drilling expected to start within months and a 3.5 km drillhole is expected to follow if no problems arise.
As a scientist I think that if this project succeeds it will give us a great insight into how what is potentially one of the destructive volcanoes on Earth works and eagerly await the results.
More information can be found at http://news.sciencemag.org/scienceinsider/2012/05/supervolcano-drilling-plan-gets.html