Coseismic Slip Vectors of 24 August and 30 October 2016 Earthquakes in Central Italy: Oblique Slip and Regional Kinematic Implications

After 24 August and 30 October 2016 central Italy earthquakes (Mw 6.0 and 6.5, respectively), photogrammetry and geodetic survey were performed at various sites along a 6-km-long portion of the rupturing Monte Vettore fault system, providing very high-resolution georeferenced 3-D point clouds and imagery of the 24 August rupture and a data set of bedrock fault scarp before/after the 30 October earthquake. The maximum coseismic displacement for both events occurs near Scoglio dell’ Aquila with an average normal dip slip of 22 ± 4 and 184 ± 6 cm, respectively. Coseismic slip vectors and meter-scale corrugation axis are oriented N280 ± 10° on the ~N140° striking main Vettore fault involving oblique normal slip with a right-lateral component and N205 ± 10° on ~N170° fault strands implying oblique normal slip with a left-lateral component. We quantify the near-field coseismic displacements of the Monte Vettore fault for the 30 October event: the footwall has been translated horizontally by 42 ± 2 cm toward the ENE and uplifted by 11 ± 2 cm. The hangingwall has moved horizontally by 26 ± 2 cm, toward the NW, in a direction parallel to the fault plane and subsided by 116 ± 2 cm. The fault geometry and our determined surface coseismic slip vectors are mechanically compatible with a σ3 = N65 ± 15°. This stress regime is consistent with the 30 October 2016 focal mechanism and the relative motion between the Adriatic microplate and the Tyrrhenian coastal region. The 30 October surface rupture results from seismic slip at depth and thus has a tectonic origin.