The 2016-17 Amatrice-Norcia-Visso Seismic Sequence Illuminated by 3-D Hypocentral Determinations and Velocity Tomograms
Abstract
The central Apennines have been struck in the past two decades by a series of seismic sequences composed by multiple mainshocks rupturing belt-parallel, adjacent normal fault segments.
The last episode occurred in 2016-17, when a cascade of nine shocks with 5.3<MW≤6.5 activated a 80km-long system composed by two main normal faults that are along-strike segmented by inherited compressional structures. We present a new 3D velocity model obtained by using 75k events selected from a large earthquakes catalogue containing 250,000 events with -1.0≤ML≤5.9, recorded by 114 permanent and temporary seismic stations during the first year of the sequence. High resolution tomographic images and accurate hypocentral locations are used to reconstruct the fault system architecture and the tectonic-lithological environment. We observe that individual fault segments are spatially controlled by the preexisting compressional structures and still not geometrically connected. Anyway, mainshocks break fault patches that, although limited and segmented by the inherited structural complexity, are now dynamically interfering during the same faulting episode. We also notice fault portions experiencing seismic activation before the mainshock, yielding first time observation of changes in the elastic properties with 4D tomography.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S21E0562C
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITY;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGY;
- 8109 Continental tectonics: extensional;
- TECTONOPHYSICS