Complete seismic release of tectonic strain and earthquake recurrence in the Apennines (Italy)

Abstract

Here I compare estimates of tectonic strain rates from dense Global Positioning System measurements with the seismicity released in the last ~500 years in the Apennines (Italy). The rates of seismic moment accumulation from geodesy and of historical seismic release by earthquakes agree within the uncertainties, ruling out significant aseismic deformation. Within the considered 400 km long section of the Apennines, this balance yields an average recurrence interval of 30–75 years for MW≥6.5 events without requiring a future earthquake larger than those observed historically (MW~7). A minimum estimate of unreleased strain allows MW≥6.5 and MW≥6.9 events to be released in ~35% and ~10% of the central‐southern Apennines, respectively. The definition of the seismic potential for smaller events is more uncertain, and their occurrence remains a significant threat throughout the Apennines.

Aseismic transient during the 2010–2014 seismic swarm: evidence for longer recurrence of M ≥ 6.5 earthquakes in the Pollino gap (Southern Italy)?

“…5) requires a M W  ≥ 6.5 event every 350–890 years. This value is slightly lower than, but similar to, the recurrence of M W  ≥ 6.5 events in the Central-Southern Apennines (240–600 years), where the spatial distribution of large macroseismic intensities in the last 1000 years does not show significant gaps 47 . Halving the seismic coupling (case 2 in Fig.…”

Source Parameters of the 2016–2017 Central Italy Earthquake Sequence from the Sentinel-1, ALOS-2 and GPS Data

“…This region is tectonically and geologically complex, involving both the subduction of the Adria microplate beneath Eurasia and subduction of the Apennines from east to west [9]. A dense array of active normal fault systems accommodate approximately 3 mm/year of extension across the chain [10]. Among the main active tectonic structures in the area are the Vettore-Bove Mountains, the Laga Mountains, and the Norcia fault system [11].…”

Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data

“…The 2016 Central Italy earthquake sequence started on 24 August with a M w 6.1 event, striking a sector of the Apennines (Figure 1) characterized by high geodetic strain rates [D'Agostino, 2014] and causing~300 casualties and extensive damage to the town of Amatrice and surroundings. The following seismic sequence was characterized by numerous aftershocks located southeast and northwest of the epicenter [Chiaraluce et al, 2017], which decreased in frequency and magnitude until the end of October, when a M w 5.9 event occurred on 26 October about 25 km to the NW of the previous main shock, between Visso and Ussita villages (Figure 1).…”