Premium
Fluid pressure, stress field and propagation style of coalescing thrusts from the analysis of the 20 May 2012 M L 5.9 Emilia earthquake (Northern Apennines, Italy)
Author(s) -
Ventura Guido,
Di Giovambattista Rita
Publication year - 2013
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/ter.12007
Subject(s) - geology , foreland basin , seismology , induced seismicity , stress field , basement , sedimentary rock , crust , aftershock , geomorphology , tectonics , geophysics , paleontology , physics , civil engineering , finite element method , engineering , thermodynamics
Terra Nova, 25, 72–78, 2013 Abstract Two major earthquakes of M L 5.9 and 5.8 and hundreds of aftershocks affected the Emilia region (Po Plain, Italy) between 20 May and June 2012. The events concentrate in the uppermost 10 km of the crust with few events up to 30 km. Two buried, sub‐parallel N100°E striking thrusts of the Northern Apennines belt are reactivated. These thrusts coalesce at the interface between the metamorphic basement of the belt and the overlying, about 10‐km thick, sedimentary succession. Focal mechanisms indicate a compressive stress field with a sub‐horizontal, roughly N‐S striking σ 1 . This stress field is consistent with active shortening in Northern Apennines. Suprahydrostatic pore pressure and σ 1 ∼ σ 2 ≠σ 3 are required to reactivate the thrusts. The involved fluids could be gas and brines hosted in the folded sedimentary successions. The time and spatial evolution of the seismicity indicates a foreland to hinterland propagation of the ruptures and a thin‐skinned deformation of Northern Apennines.