GNGTS 2016 - Atti del 35° Convegno Nazionale

128 GNGTS 2016 S essione 1.1 After relocation, seismicity ������ ���� ��� �������������������� ������ �� ����� ������ mainly rims the Argentera-Mercantour Massif on three sides, with an aseismic corridor some 10 km wide observed on the southeastern side of the massif (Fig. 1). This corridor marks the transition to the Saorge-Taggia Fault. In the map of relocated events, only few of them occur within the massif, in particular in the south-western sector. The dense distribution of seismic events north-east of the Stura Fault is confirmed, although it now appears less chaotic and partly organized in separate sectors, one linked to the Stura Fault and the other one linked to the Penninic arc. The SW-NE cross-sections of Fig. 2 provide new insights about the distribution of seismicity under the Argentera-Mercantour Massif. Both cross-sections show a rimming of the seismicity around the massif extending to 9-10 km depth. One important feature is the subvertical trend shown in section CD in correspondence of the Stura Fault, where a few moderate magnitude earthquakes possibly attest to its ongoing activity. Although the kinematic framework on a more regional scale is well constrained by some focal mechanisms computed for earthquakes with magnitude > 4, only few focal mechanisms Fig. 3 – Distribution of HypoDD relocated seismicity with principal fault plane solutions. In red focal mechanisms for events with magnitude greater than 4 and in grey focal solutions for the Argentera area. Fig. 2 – Seismic cross-sections oriented as in Fig. 1.