Boiling mud and sulphuric steam
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Deep drilling carried out near Naples to study volcano risk

6 August 2012 Last updated at 17:50 BST

Italian scientists are drilling 3.5km into the ground beneath the Phlegraen Fields near Naples to monitor a dormant underground volcano.

They are hoping to set up a system which could give an early warning of possible eruptions - but there are some who fear the drilling could itself trigger an eruption.

Marek Pruszewicz reports.