Publication Date:
2022-06-13
Description:
Three 2-D Deep Electrical Resistivity Tomography (ERT) transects, up to 6.36 km long, were
obtained across the Paganica-San Demetrio Basin, bounded by the 2009 L’Aquila Mw 6.1
normal-faulting earthquake causative fault (central Italy). The investigations allowed defining
for the first time the shallow subsurface basin structure. The resistivity images, and their geological
interpretation, showa dissected Mesozoic-Tertiary substratum buried under continental
infill of mainly Quaternary age due to the long-term activity of the Paganica-San Demetrio
normal faults system (PSDFS), ruling the most recent deformational phase. Our results indicate
that the basin bottom deepens up to 600 m moving to the south, with the continental
infill largely exceeding the known thickness of the Quaternary sequence. The causes of this
increasing thickness can be: (1) the onset of the continental deposition in the southern sector
took place before the Quaternary, (2) there was an early stage of the basin development driven
by different fault systems that produced a depocentre in the southern sector not related to the
present-day basin shape, or (3) the fault system slip rate in the southern sector was faster than
in the northern sector. We were able to gain sights into the long-term PSDFS behaviour and
evolution, by comparing throw rates at different timescales and discriminating the splays that
lead deformation. Some fault splays exhibit large cumulative throws (〉300 m) in coincidence
with large displacement of the continental deposits sequence (〉100 m), thus testifying a general
persistence in time of their activity as leading splays of the fault system. We evaluate the
long-term (3–2.5Myr) cumulative and Quaternary throw rates of most of the leading splays to
be 0.08–0.17 mm yr−1, indicating a substantial stability of the faults activity. Among them, an
individual leading fault splay extends from Paganica to San Demetrio ne’ Vestini as a result
of a post-Early Pleistocene linkage of two smaller splays. This 15 km long fault splay can
explain the Holocene surface ruptures observed to be larger than those occurred during the
2009 L’Aquila earthquake, such as revealed by palaeoseismological investigations. Finally, the
architecture of the basin at depth suggests that the PSDFS can also rupture a longer structure
at the surface, allowing earthquakes larger than M 6.5, besides rupturing only small sections,
as it occurred in 2009.
Description:
Published
Description:
967–982
Description:
2TR. Ricostruzione e modellazione della struttura crostale
Description:
JCR Journal
Keywords:
electrical properties
;
tectonics and landscape evolution
;
neotectonics
;
fractures and faults
;
04.02. Exploration geophysics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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