The closest airports are in Rome (Fiumicino Airport & Ciampino Airport) and in Pescara (Aeroporto internazionale d’Abruzzo). From Ciampino and Fiumicino there is a direct bus to l’Aquila (you can see timetable and fares here http://www.gasparionline.it/), which will leave you in Hotel Amiternum. From there take any bus going towards the city centre and get off at Terminalbus Collemaggio. GSSI is 5/10 mins walking from Terminal bus (Collemaggio Park), as you can see from the map . Also taxi are normally available at Hotel Amiternum.
Drivers can take highway A24 from Rome and take the exit L’Aquila Ovest; then,follow the road signs to the city center and those with the logo of the GSSI.
L’Aquila railway station is not well connected, therefore by train you should better arrive to Rome or to Giulianova and Pescara (for those traveling on the East coast along the Adriatic sea). From there (Roma Tiburtina or Giulianova and Pescara railway station) there are TUA; FLIXBUS buses leading to L’Aquila, which will arrive at Terminal bus Collemaggio. GSSI is 5/10 mins walking from Terminal bus (Collemaggio Park), as you can see from the map.