Deep structure and tectonics of the northern‐central Apennines as seen by regional‐scale tomography and 3‐D located earthquakes

Abstract

[1] In this study we present new high-resolution, regional-scale, Vp and Vp/Vs models of the northern-central Apennines along with accurate 3-D locations of a large set of local earthquakes. The main velocity anomalies are consistent with the surface geology in the shallow layers and present evidence for fluids stored within the basement at greater depths beneath the extensional belt. The Adria and Tyrrhenian mantle are defined by positive velocity anomalies below 30 km depth, while a low-Vp, high-Vp/Vs region in between indicates the existence of a hydrated wedge. The results yield new constraints on active processes in the Apennines and more generally envisage the evolution of a postcollisional belt. Velocity anomalies and earthquakes are consistent with a complex system of delamination and sinking of the Adria continental lithosphere, with the peeling of the crust identified by intermediate-depth seismicity. Change of seismicity and structural patterns along the belt indicates that this tectonic process is diachronous and that fluids, released by sunken lithosphere, are stored within the crust, conditioning the occurrence of seismicity and the onset of extension.Citation: Carannante, S., G. Monachesi, M. Cattaneo, A. Amato, and C. Chiarabba (2013), Deep structure and tectonics of the northern-central Apennines as seen by regional-scale tomography and 3-D located earthquakes,

Assessment of earthquake locations in 3‐D deterministic velocity models: A case study from the Altotiberina Near Fault Observatory (Italy)

“…(a) Map of the study area and acquisition geometry: permanent and temporary seismic stations are represented with red and green inverted triangles, respectively. Dark and light gray dots are the preliminary hypocenter locations of the two selected data sets computed in the 1‐D velocity model of Carannante et al [] (see the text for further details); blue diamonds indicate the position of San Donato well (SD), Monte Civitello 1 well (MC), Perugia 1 well (P), Burano well (B), and Pieve di Santo Stefano well (ST). The three “beach balls” show the Time Domain Moment Tensor (TDMT) focal mechanism solutions of the M w 3.6 Pietralunga earthquake (15 April 2010), the M w 3.6 Città di Castello earthquake (8 May 2013), and the M w 3.9 Gubbio earthquake (22 December 2013) ( http://cnt.rm.ingv.it/tdmt).…”

A mixed automatic-manual seismic catalog for Central-Eastern Italy: analysis of homogeneity

“…As already described in Carannante et al [2013], the most complex depth distribution is related to the central sections (from 11 to 15). Here the NE-ward deepening of the shallow seismicity appears less evident, and a deeper seismogenic layer is present starting at the NE bound of this seismicity, concentrated between 15 and 25 km.…”

“…It can be observed that for a quite large subset of the analyzed area a rather narrow definition of the main A MIXED SEISMIC CATALOG FOR C-E ITALY seismogenic layer is possible; in particular some specific trends, already described e.g. in de Luca et al [2009] and in Carannante et al [2013] can be recognized. A detailed discussion of this result is beyond the scope of this paper; here we just want to compare this result with the analogous obtained by using just the automatic locations present in the catalog (Figure 13b).…”

“…Both in the map view and in the cross-sections, the manual locations are reported as black dots and the automatic ones as red dots. These sections can be compared with those presented in De Luca et al [2009] and in Carannante et al [2013]; the main difference is that in this case a very simplified location model is adopted and automatic locations are CATTANEO ET AL.…”

“…A description of the tectonic framework is beyond the scope of this paper [see e.g. Carannante et al 2013, for a description of the same area].…”