ISNet – Irpinia seismic network is the infrastructure of the Irpinia Near – Fault Observatory (INFO). ISNet is a dense, six-component high-resolution seismic network of 31 stations deployed in Southern Apennines (Italy) along the active fault system responsible for the 1980, November 23, Ms 6.9 Campania – Lucania earthquake. ISNet is an on-the-field laboratory aimed at characterizing the mechanical processes occurring along the Southern Apennines fault systems from the detailed analysis of the microseismicity and the role of fluids in seismicity generation. ISNet is also the backbone of Earthquake Early warning systems tested in Italy.