Introducing the special issue on the 2009 L’Aquila earthquake

The 28th National Congress of the Gruppo Nazionale di Geofisica della Terra Solida held in Trieste in November 2009, hosted a special session dedicated to the earthquake that only six months before devastated L’Aquila and many ancient villages spread along the Aterno Valley (Abruzzo, central Italy). We resume here the main geophysical characteristics of that long seismic sequence, before introducing in brief the contents of eight papers that we have solicited amongst the thirty-seven presented in Trieste, plus other three coming from other sessions, all of them dealing with the L’Aquila earthquake.