Mappingand evaluating kinematics and stress/strain field at active faults and fissures: a comparison between field and drone data at NE Rift,Mt Etna (Italy)

Abstract. We collected drone data to quantify the kinematics at extensional fractures and normal faults, integrated this information with seismological data to reconstruct the stress field, and critically compared the results with previous fieldwork to assess the best practice. As key site, we analysed a sector of the North-East Rift of Mt Etna, an area affected by continuous ground deformation linked to gravity sliding of the volcano's eastern flank and dyke injection. The studied sector is characterized also by the existence of eruptive craters and fissures and lava flows. This work shows that this rift segment is affected by a series of NE-striking, parallel extensional fractures characterized by an opening mode along an average N105.7° vector. Normal faults strike parallel to the extensional fractures, although they tend to bend slightly when crossing topographic highs corresponding to pyroclastic cones. The extensional strain obtained by cumulating the net offset at extensional fractures with the fault heave gives a stretching ratio of 1.003 in the northeastern part of the study area and 1.005 in the southwestern part. Given a maximum age of 1614 yr AD for the offset lavas, we obtained an extension rate of 1.9 cm/yr for the last 406 yr. The stress field is characterised by a σHmin trending NW-SE. Results indicate that Structure-from-Motion photogrammetry applied to drone surveys allows to collect large amounts of data with a resolution of 2–3 cm, a detail comparable to field surveys. In the same amount of time, drone survey can allow to collect more data than classical fieldwork, especially in logistically difficult rough terrains.