Using seismic attributes in seismotectonic research an application to the Norcia M_w?=?6.5 earthquake (30 October 2016) in central Italy

摘要

In seismotectonic studies, seismic reflection data are a powerfultool to unravel the complex deep architecture of active faults. Suchtectonic structures are usually mapped at the surface through traditionalgeological surveying, whilst seismic reflection data may help to trace theircontinuation from the near surface down to hypocentral depths. On seismicreflection data, seismic attributes are commonly used by the oil and gasindustry to aid exploration. In this study, we propose using seismicattributes in seismotectonic research for the first time. The study area isa geologically complex region of central Italy, struck during 2016–2017by a long-lasting seismic sequence, including a M _(w) 6.5 main shock. Threevintage seismic reflection profiles are currently the only ones available atthe regional scale across the epicentral zone. These represent a singularopportunity to attempt a seismic attribute analysis by running attributeslike the “energy” and the “pseudo-relief”. Our results are critical, asthey provide information on the relatively deep structural setting, mappinga prominent, high-amplitude regional reflector interpreted as the top ofbasement, which is an important rheological boundary. Complex patterns ofhigh-angle discontinuities crossing the reflectors have also been identifiedby seismic attributes. These steeply dipping fabrics are interpreted as theexpression of fault zones belonging to the active normal fault systemsresponsible for the seismicity of the region. Such peculiar seismicsignatures of faulting are consistent with the principal geological andtectonic structures exposed at surface. In addition, we also provideconvincing evidence of an important primary tectonic structure currentlydebated in the literature (the Norcia antithetic fault) as well as severalburied secondary fault splays. This work demonstrates that seismic attributeanalysis, even if used on low-quality vintage 2D data, may contribute toimproving the subsurface geological interpretation in areas characterized bylimited and/or low-quality subsurface data but with potentially high seismichazard.