Gravity mapping of basement depth in seismogenic, fault-controlled basins: The case of Middle Aterno Valley (Central Italy)

• Published in: Tectonophysics 2021-10, Vol.817, p.229044, Article 229044
• Main Authors: Florio, G., Milano, M., Cella, F.
• Format: Article
• Language: English
• Subjects: 3D gravity modelling; Apennine intermontane basins; Basement morphology; Basements; Basins; Carbonates; Constraint modelling; Density distribution; Depth; Earthquakes; Environmental risk; Fault-controlled basin architecture; Geophysical studies; Geophysics; Gravity anomalies; Gravity data; Human settlements; Iterative methods; ITRESC method; L'Aquila basin; Middle Aterno Valley; Modelling; Rescaling; Seismic activity; Seismic hazard; Shaking; Thickness; Three dimensional models; Two dimensional models; Valleys
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2021.229044

Ground-shaking phenomena in intermontane basins emplaced in seismically active areas are strongly affected by sediment thickness. There, the development of human settlements, encouraged because of the flat topography in a mostly mountainous region, implies demographic growth and an increased seismic risk, as recent earthquakes in Central Italy confirmed. The knowledge of the thickness of the basin infills and of their density distribution is critical for the ground-motion amplification analysis. We apply the recently proposed ITerative RESCaling (ITRESC) method for 3D gravity modelling to the Middle Aterno Valley (Apennines, central Italy), a fault-controlled basin where a strong seismic activity recently occurred. Although the structural framework was previously investigated through 1D or 2D geophysical studies, here for the first time a full 3D model of the carbonate basement morphology is computed by the inversion of gravity data. Differently from usual gravity modelling approaches, the ITRESC technique 1) does not assume a density contrast function, which is instead determined through a data-driven process, and 2) integrates geological or geophysical constraints to define a global “gravity/depth-to-basement” rescaling law, valid in all the investigated area. Our model integrates a number of depth constraints of different nature while at the same time honoring the gravity anomalies. The obtained gravity model of the basement depth shows several analogies with previous studies, although with significant, localized discrepancies. The results of this study are only partially consistent with a structural evolution of the Middle Aterno Valley through a polyphasic sequence, as previously hypothesized. •Gravity models of basement can be useful for seismic amplification studies.•A 3D gravity basement model of Middle Aterno Valley is computed by ITRESC method.•The gravity modelling did not assume the density contrast, which was instead estimated.•Results are consistent with a polyphasic structural evolution of the basin.