Field investigations performed in the epicentral area within the days following the April 6, 2009 L’Aquila earthquake (M w 6.3) allowed several researchers to detect evidence of coseismic ground rupturing. This has been found along the Paganica Fault and next to minor synthetic and antithetic structures. Although a lot of geo-structural and geophysical investigations have been recently used to characterize these structures, the role of the different fault segments–ie as primary or secondary faults–and their geometrical characteristics are still a matter of debate. In light of this, we have here integrated data derived from fluid geochemistry analyses carried out soon after the main-shock with field structural investigations. In particular, we compared structural data with CO 2 and CH 4 flux measurements, as well as with radon concentration measurements (for other geogas concentration see V oltattorni N., this issue). Our aim was to better define the structural features and complexities of the activated Paganica Fault. Here, we show that, in the near rupture zone,“geochemical signatures” could be a powerful method to detect earthquake activated fault segments, even if they show subtle or absent geological-geomorphological evidence and are still partially “blind”. In detail, a clear degassing zone was identified just along the San Gregorio coseismic fracture zone–ie, the surface deformation related to the “blind” San Gregorio normal fault. Indeed, CO 2 and CH 4 flux maximum anomalies were aligned along the Northern sector of the San Gregorio fault, in the Bazzano industrial area as well as at the border of the studied area (Fossa antitethic fault crossing an anti-apenninic transverse belt). The Bazzano-San Gregorio fault area also corresponds to the depocenter of the maximum coseismic deformation highlighted by DInSAR analysis (A tzori et alii, 2009). Here, maximum radon concentration values in soil gases were also found. As a whole, these results corroborates the hypothesis of B oncio et alii (2010) who suggested that the San Gregorio fault probably represents a synthetic splay of the Paganica Fault, being thus connected with the main seismogenic fault at depth.