ESA has a real techie article on this ... here's the incipit (just after this my jet-lag-addled brain gives up):

Satellite images acquired by ESA’s Envisat satellite have revealed the volcanic region of the Phlegrean Fields, located in southern Italy near the city of Naples, has entered a new uplift phase.

Using Differential SAR Interferometry (DInSAR), scientists at the Institute for the Electromagnetic Sensing of the Environment (IREA) of the Italian National Research Council (CNR) mapped the changes in the caldera – a ring-shaped region which includes several volcanoes – and discovered the area has uplifted about 2.8 centimetres from 2005 to 2006.

The original article has a realllllllllllly nice satellite image of the Bay of Naples (click on it for a larger version) ...