Italy's National Institute of Geophysics and Volcanology (INGV) said the quake struck at 15:48 (14:48 GMT), with its epicentre in Garfagnana.

BBC: Italy: Earthquake hits near Bologna

Volcanologist Sonia Calvari, of the Institute of Geophysics and Volcanology in Catania (INGV-CT), said rapid advances in technology enable experts to use a wide range of methods to continually map and monitor Etna from a distance.

CNN: Keeping track of Etna's pulse

Fabio Picuti, the public prosecutor, stresses that the charge is not about whether the experts, who included Enzo Boschi, then president of the National Institute of Geophysics and Vulcanology (INGV), should have predicted exactly when, where and with what force the earthquake would have struck.

ECONOMIST: An extraordinary manslaughter trial starts in Italy