Articles | Volume 17, issue 11
https://doi.org/10.5194/nhess-17-1885-2017
https://doi.org/10.5194/nhess-17-1885-2017
Brief communication
 | 
09 Nov 2017
Brief communication |  | 09 Nov 2017

Brief communication: Co-seismic displacement on 26 and 30 October 2016 (Mw = 5.9 and 6.5) – earthquakes in central Italy from the analysis of a local GNSS network

Giorgio De Guidi, Alessia Vecchio, Fabio Brighenti, Riccardo Caputo, Francesco Carnemolla, Adriano Di Pietro, Marco Lupo, Massimiliano Maggini, Salvatore Marchese, Danilo Messina, Carmelo Monaco, and Salvatore Naso

Abstract. On 24 August 2016 a strong earthquake (Mw = 6.0) affected central Italy and an intense seismic sequence started. Field observations, DInSAR (Differential INterferometry Synthetic-Aperture Radar) analyses and preliminary focal mechanisms, as well as the distribution of aftershocks, suggested the reactivation of the northern sector of the Laga fault, the southern part of which was already rebooted during the 2009 L'Aquila sequence, and of the southern segment of the Mt Vettore fault system (MVFS). Based on this preliminary information and following the stress-triggering concept (Stein, 1999; Steacy et al., 2005), we tentatively identified a potential fault zone that is very vulnerable to future seismic events just north of the earlier epicentral area. Accordingly, we planned a local geodetic network consisting of five new GNSS (Global Navigation Satellite System) stations located a few kilometres away from both sides of the MVFS. This network was devoted to working out, at least partially but in some detail, the possible northward propagation of the crustal network ruptures. The building of the stations and a first set of measurements were carried out during a first campaign (30 September and 2 October 2016). On 26 October 2016, immediately north of the epicentral area of the 24 August event, another earthquake (Mw = 5.9) occurred, followed 4 days later (30 October) by the main shock (Mw = 6.5) of the whole 2016 summer–autumn seismic sequence. Our local geodetic network was fully affected by the new events and therefore we performed a second campaign soon after (11–13 November 2016). In this brief note, we provide the results of our geodetic measurements that registered the co-seismic and immediately post-seismic deformation of the two major October shocks, documenting in some detail the surface deformation close to the fault trace. We also compare our results with the available surface deformation field of the broader area, obtained on the basis of the DInSAR technique, and show an overall good fit.

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Short summary
In this paper we provide new and original data which show the deformation behaviour close to the seismogenic segment of the Mt Vettore normal fault system during co-seismic deformation (30 October 2016 Mw  = 5.9. This foresight allowed us to record the second (strongest) event (Mw  = 6.5) of 30 October 2016. We identified the specific fault zone that was most vulnerable to future seismic events just north of the fault segment that reactivated on 24 August.
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