”La Sapienza” University, Physics Department, and INFM, Center for Statistical Mechanics and Complexity, Roma, Italy

Seismicity is recognized to be a complex natural phenomenon either in space, time and energy domains: earthquakes occur as a sudden energy release after a strongly variable time period of stress accumulation, in locations not deterministically defined, with magnitude range spanning over several orders. But seismicity is certainly not a pure random process: spatial locations of events clearly display correlations with tectonic structures at all scales (from plates borders to small faults settings); on the other hand time evolution is clearly linked with strongest shocks occurrence and energy distribution displays hierarchical features. Although it is still not possible to propose deterministic models for earthquakes, well established statistical relations constrain seismicity under very specific and intriguing relations.