Introduction
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A seismogenic low-angle normal fault (LANF) can be formed at dips of around 30° or less (Axen, 2007) but these faults are not predicted by Andersonian theory (1942) that is fundamental to interpreting the stress state and physical constitution of the crust. Andersonian fault mechanics predict that normal fault dips of less than 30° cannot slip; indeed, the global compilations of normal fault focal mechanism show only a small fraction of events with either nodal plane dipping less than 30°. There remain persistent doubts that LANFs either initiate or slip at shallow dips (<30°).
In a general form, the low-angle fault relationship consists of steeply tilted hanging wall strata resting on extensive flat- to gently-dipping fault surfaces (Davis, 1984). The footwall rocks beneath the low-angle normal slip faults represent deep levels of the geological column. The individual LANFs in the Basin and Range province slipped 5-50 km and several of these exhumed mid-crustal rocks (Anderson, 1971; Armstrong, 1972; Wright and Troxel, 1973; Wernicke, 1981; Wernicke et al., 1988). LANFs are globally significant and occur in the geologic records of most continents (e.g. Holm, 1996; Axen et al., 1999) in both extensional and contractional settings (e.g. Selverstone, 1988; Burchfiel et al., 1992), as well as slow spreading mid-oceanic ridges (e.g. Tucholke and Lin, 1998). The evidence of low-angle normal faults related to seismicity has been observed from the Santa Rita Fault of the Tucson basin (Johnson and Loy, 1992), the Lamoille Valley Fault in the Basin and Range Province (Smith et al., 1989; Wernicke, 1995), the Altotiberina Faults (ATF) from central Italy (Barchi et al., 2008; Boncio et al., 2000), and the Strait of Messina in Southern Italy (Catalano et al., 2008; Monaco and Tortorici, 2000).
Our aim is to create a structurally complex, three-dimensional model of the Strait of Messina to more accurately simulate the kinematics of the Messina Fault (MF) i.e., a seismogenic low angle normal fault (<30°). 3D modeling, in our view, is a necessary tool in understanding the natural behavior of this structural setting. The changes in topography and the development of different faults with different amounts of displacement can predict future movements along the fault planes. Here we have generated three 3D models with the help of a sandbox (Bonini et al., in prep.) for explaining the geodynamic evolution of the area.