Abstract
Abstract. In seismotectonic studies, seismic reflection data are a powerful tool to unravel the complex deep architecture of active faults. Such tectonic structures are usually mapped at the surface through traditional geological surveying, whilst seismic reflection data may help to trace their continuation from the near surface down to hypocentral depths. On seismic reflection data, seismic attributes are commonly used by the oil and gas industry to aid exploration. In this study, we propose using seismic attributes in seismotectonic research for the first time. The study area is a geologically complex region of central Italy, struck during 2016–2017 by a long-lasting seismic sequence, including a Mw 6.5 main shock. Three vintage seismic reflection profiles are currently the only ones available at the regional scale across the epicentral zone. These represent a singular opportunity to attempt a seismic attribute analysis by running attributes like the “energy” and the “pseudo-relief”. Our results are critical, as they provide information on the relatively deep structural setting, mapping a prominent, high-amplitude regional reflector interpreted as the top of basement, which is an important rheological boundary. Complex patterns of high-angle discontinuities crossing the reflectors have also been identified by seismic attributes. These steeply dipping fabrics are interpreted as the expression of fault zones belonging to the active normal fault systems responsible for the seismicity of the region. Such peculiar seismic signatures of faulting are consistent with the principal geological and tectonic structures exposed at surface. In addition, we also provide convincing evidence of an important primary tectonic structure currently debated in the literature (the Norcia antithetic fault) as well as several buried secondary fault splays. This work demonstrates that seismic attribute analysis, even if used on low-quality vintage 2D data, may contribute to improving the subsurface geological interpretation in areas characterized by limited and/or low-quality subsurface data but with potentially high seismic hazard.
Highlights
Studying the connections between earthquakes and the faults with which they are associated is a primary goal of seismotectonics (Allen et al, 1965; Schwartz and Coppersmith, 1984)
Taking into account the important role that seismic attributes play in the oil and gas industry, their usage might be of high interest and impact for improving the geological interpretation of vintage seismic data aimed at other scientific objectives
Legacy data powered by seismic attributes, when combined with seismological data, may have a high potential impact for the identification and characterization of possible seismogenic structures and eventually earthquake hazard assessment
Summary
Studying the connections between earthquakes and the faults with which they are associated is a primary goal of seismotectonics (Allen et al, 1965; Schwartz and Coppersmith, 1984). Within this field, it is generally complex to fill the gap between the exposed geology (including the active “geological faults”) and the seismological data (e.g., focal mechanisms, earthquake locations, etc.), indicators of the geometry and kinematics of the seismic source at hypocentral depth (“seismological faults”, sensu Barchi and Mirabella, 2008). The recovery of information on the seismogenic structures at depth is difficult, primarily due to the lack of high-resolution geophysical data and/or well stratigraphy. Ercoli et al.: Using seismic attributes in seismotectonic research data results in relatively high degrees of uncertainty and drives contrasting geological models and interpretations
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