Abstract
In this study, joint inversions of Synthetic Aperture Radar (SAR) and Global Position System (GPS) measurements are used to investigate the source parameters of four Mw > 5 events of the 2016–2017 Central Italy earthquake sequence. The results show that the four events are all associated with a normal fault striking northwest–southeast and dipping southwest. The observations, in all cases, are consistent with slip on a rupture plane, with strike in the range of 157° to 164° and dip in the range of 39° to 44° that penetrates the uppermost crust to a depth of 0 to 8 km. The primary characteristics of these four events are that the 24 August 2016 Mw 6.2 Amatrice earthquake had pronounced heterogeneity of the slip distribution marked by two main slip patches, the 26 October 2016 Mw 6.1 Visso earthquake had a concentrated slip at 3–6 km, and the predominant slip of the 30 October 2016 Mw 6.6 Norcia earthquake occurred on the fault with a peak magnitude of 2.5 m at a depth of 0–6 km, suggesting that the rupture may have reached the surface, and the 18 January 2017 Mw 5.7 Campotosto earthquake had a large area of sliding at depth 3–9 km. The positive static stress changes on the fault planes of the latter three events demonstrate that the 24 August 2016 Amatrice earthquake may have triggered a cascading failure of earthquakes along the complex normal fault system in Central Italy.
Highlights
A sequence of earthquakes from 2016 to 2017 occurred in Central Italy, including ten Mw ≥ 5.0 earthquakes and their aftershocks (Table 1 and Figure 1)
From the focal mechanism solutions released by different institutions, we can see that these four events all occurred as the result of shallow normal faulting in the Central Apennines (Tables 3−5)
The recorded Central Italy earthquake sequence since 24 August 2016 consists of four main events initiated by an Mw 6.2 earthquake along the Gorzano and Vettore faults
Summary
A sequence of earthquakes from 2016 to 2017 occurred in Central Italy, including ten Mw ≥ 5.0 earthquakes and their aftershocks (Table 1 and Figure 1). The largest earthquake (Mw 6.6) in this sequence occurred approximately between the location of the 24 August and 26 October 2016 events [1]. Since the occurrence of the 24 August 2016 event, approximately more than 20,000 earthquakes of M 2~5 were recorded by Institute of Geophysics and Volcanology (INGV) within ten months (Figure 1) [12]. This data set provides an opportunity to track the spatiotemporal evolution of seismicity and to investigate the interactivity of the earthquake sequence. Considering the different decay history of the four periods, we regard these four events as the independent shock type, rather than the main shock–aftershock type
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