We show the results of the inversion of a new geodetic dataset, involving both remote sensing and ground-based data: high precision levelling data, GPS observations and Differential Synthetic Aperture Radar Interferometry (DInSAR) products covering the 2012 Emilia seismic sequence and the following one year of post-seismic deformation. As far as DInSAR analysis, we used data acquired by the RADARSAT-2 (RSAT2) satellite from the Canadian Space Agency and by the COSMO-SkyMed (CSK) constellation developed by the Italian Space Agency in cooperation with the Ministry of Defense. For what attains the RSAT2 mission, we considered a single interferometric pair only, involving the 30 April and 17 June 2012 stripmap acquisitions, aimed at measuring the cumulative coseismic ground displacement due to the two mainshocks (20 and 29 May 2012). As for the CSK mission, a dataset of 12 stripmap images covering a time interval of almost one year, from 27 May 2012 to 7 May 2013, allowed measuring the coseismic displacement field relevant to the 29 May mainshock as well as one year of post-seismic deformation. To retrieve the CSK deformation time series relevant to the post-seismic sequence, we applied the Small BAseline Subset (SBAS) algorithm [Berardino et al., 2002], specifically the one in Fornaro et al. [2009]. By use of the geodetic dataset together with a catalog of relocated aftershocks, we modeled rupture geometries, and the coseismic and post-seismic slip distributions for the two main events (MW 6.1 and 6.0) of the sequence, allowing us to suggest the influence of structure and/or lithology on slip propagation in intracontinental settings. Moreover, we explored how these thrust events have interacted with each other and, defining the Coulomb stress changes, how first mainshock triggered following activity. Our results also indicate that between the two main events, a third thrust segment was activated by first mainshock, releasing a pulse of aseismic slip equivalent to a MW 5.8 event. We also hypothesized that the aseismic slip event probably brought the second fault closer to failure. Generally, we found that among continental en echelon thrusts, stress transfer and interaction between earthquakes and aseismic slip may play an important role in the way they activate during a seismic sequence. References Berardino, P., Fornaro, G., Lanari, R. and Sansosti, E (2002). A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms, IEEE Trans. Geosci. Remote Sens., 40, 2375-2383 Fornaro, G., Pauciullo, A. and Serafino, F. (2009). Deformation monitoring over large areas with multipass differential SAR interferometry: a new approach based on the use of spatial differences, Int. J. Remote Sens., 30, 1455-1478.
The 2012 Emilia earthquake sequence (Northern Italy): evidence for fault activation and stress transfer between en echelon thrusts from a new geodetic dataset
Bonano M;Fornaro G;Lanari R;Reale D;
2016
Abstract
We show the results of the inversion of a new geodetic dataset, involving both remote sensing and ground-based data: high precision levelling data, GPS observations and Differential Synthetic Aperture Radar Interferometry (DInSAR) products covering the 2012 Emilia seismic sequence and the following one year of post-seismic deformation. As far as DInSAR analysis, we used data acquired by the RADARSAT-2 (RSAT2) satellite from the Canadian Space Agency and by the COSMO-SkyMed (CSK) constellation developed by the Italian Space Agency in cooperation with the Ministry of Defense. For what attains the RSAT2 mission, we considered a single interferometric pair only, involving the 30 April and 17 June 2012 stripmap acquisitions, aimed at measuring the cumulative coseismic ground displacement due to the two mainshocks (20 and 29 May 2012). As for the CSK mission, a dataset of 12 stripmap images covering a time interval of almost one year, from 27 May 2012 to 7 May 2013, allowed measuring the coseismic displacement field relevant to the 29 May mainshock as well as one year of post-seismic deformation. To retrieve the CSK deformation time series relevant to the post-seismic sequence, we applied the Small BAseline Subset (SBAS) algorithm [Berardino et al., 2002], specifically the one in Fornaro et al. [2009]. By use of the geodetic dataset together with a catalog of relocated aftershocks, we modeled rupture geometries, and the coseismic and post-seismic slip distributions for the two main events (MW 6.1 and 6.0) of the sequence, allowing us to suggest the influence of structure and/or lithology on slip propagation in intracontinental settings. Moreover, we explored how these thrust events have interacted with each other and, defining the Coulomb stress changes, how first mainshock triggered following activity. Our results also indicate that between the two main events, a third thrust segment was activated by first mainshock, releasing a pulse of aseismic slip equivalent to a MW 5.8 event. We also hypothesized that the aseismic slip event probably brought the second fault closer to failure. Generally, we found that among continental en echelon thrusts, stress transfer and interaction between earthquakes and aseismic slip may play an important role in the way they activate during a seismic sequence. References Berardino, P., Fornaro, G., Lanari, R. and Sansosti, E (2002). A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms, IEEE Trans. Geosci. Remote Sens., 40, 2375-2383 Fornaro, G., Pauciullo, A. and Serafino, F. (2009). Deformation monitoring over large areas with multipass differential SAR interferometry: a new approach based on the use of spatial differences, Int. J. Remote Sens., 30, 1455-1478.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
