Interseismic coupling, seismic potential, and earthquake recurrence on the southern front of the Eastern Alps (NE Italy)

Abstract

Here we use continuous GPS observations to document the geodetic strain accumulation across the South‐Eastern Alps (NE Italy). We estimate the interseismic coupling on the intracontinental collision thrust fault and discuss the seismic potential and earthquake recurrence. We invert the GPS velocities using the back slip approach to simultaneously estimate the relative angular velocity and the degree of interseismic coupling on the thrust fault that separates the Eastern Alps and the Venetian‐Friulian plain. Comparison between the rigid rotation predicted motion and the shortening observed across the area indicates that the South‐Eastern Alpine thrust front absorbs about 70% of the total convergence between the Adria and Eurasia plates. The coupling is computed on a north dipping fault following the continuous external seismogenic thrust front of the South‐Eastern Alps. The modeled thrust fault is currently locked from the surface to a depth of ≈10 km. The transition zone between locked and creeping portions of the fault roughly corresponds with the belt of microseismicity parallel and to the north of the mountain front. The estimated moment deficit rate is 1.3 ± 0.4 × 1017 Nm/yr. The comparison between the estimated moment deficit and that released historically by the earthquakes suggests that to account for the moment deficit the following two factors or their combination should be considered: (1) a significant part of the observed interseismic coupling is released aseismically and (2) infrequent “large” events with long return period (> 1000 years) and with magnitudes larger than the value assigned to the largest historical events (Mw≈ 6.7).

Present-day surface deformationof the Alpine Region inferred from geodetic techniques

“…This compression presents maximum strain-rate values of about 20 x 10 -9 a -1 in the Venetian-Friuli and Po Basins. These findings are in agreement with previous works published by Serpelloni et al (2005Serpelloni et al ( , 2006, Caporali et al (2009), Bennett et al (2012 and Cheloni et al (2014). Nevertheless, the lack of data in the eastern margin of the Adriatic Sea does not permit to conclude if this shortening continues with similar Calais et al (2002) and Delacou et al (2008).…”

“…The polarity of subduction changes from one area to the other: while the European 5 lithosphere is subducted beneath the Alps, the African lithosphere is subducted beneath the Apennines and the Dinarides-Hellenides (Argnani, 2009). In this way, Alps, Apennines, and Dinarides-Hellenides are still active orogens, although at different rates (D'Agostino et al, 2005;Devoti et al 2008;Cuffaro et al, 2010;Cheloni et al, 2014). Each subduction is associated with the usual vertical motions; i.e., subsidence in the foreland basin and uplift in the mountain belt.…”

First evidence of active transpressive surface faulting at the front of the eastern Southern Alps, northeastern Italy: insight on the 1511 earthquake seismotectonics

“…8). Ultimately, this study raises significant issues on a potential major seismogenic source of a region where interseismic coupling suggests elastic strain is building up at seismogenic depths which will be released in future large earthquakes (Cheloni et al, 2014;Serpelloni et al, 2016).…”

Insights on continental collisional processes from GPS data: Dynamics of the peri‐Adriatic belts

“…Over the past few years, several GPS studies brought new insights on the deformation pattern around the Adriatic Sea. First, the nearly rigid rotation of the Adria and Apulia microplates forming the core of the Adriatic domain generates a 2 to 4 mm/yr northeastward motion into the Eastern and Central Alps [e.g., D'Agostino et al , ; Cheloni et al , ] and into the Dinarides [e.g., Serpelloni et al , ; D'Agostino et al , ; Nocquet , ]. Furthermore, the eastward motion of the Eastern Alps toward the Pannonian Basin has been extensively discussed and analyzed [e.g., Robl and Stüwe , ; Selverstone , ; Ratschbacher et al , ].…”