We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting.
The assessment of deformation types within the slope of a carbonate platform can be complicated by the\ud possible interaction of rooted (tectonically-induced) and superficial (gravity-driven) structures. An ideal\ud case study to document and distinguish tectonically- and gravity-driven structures is provided by the\ud Cretaceous slope-to-basin carbonates exposed in the Gargano Promontory, southern Italy. These carbonates\ud formed adjacent to the Apulian platform margin, which was oriented approximately NEeSW to\ud NWeSE along the southern and northern edges of the promontory, respectively. Slump-related folds are\ud characterised by axial planes typically oriented either sub-parallel or at small angles to the strike of the\ud inferred paleoslope. In fact, the strike of folds is roughly NEeSW in the southern portion of the study\ud area, whereas it is NWeSE in the northern part. Correspondingly, gravity-driven normal and reverse\ud faults strike sub-parallel and at acute angles to the adjacent Apulian paleoslope. Cretaceous tectonic\ud faults in the slope-to-basin carbonates form two principal sets striking NWeSE and WNW-ESE. The\ud former set is made up of normal faults and the latter one includes mainly oblique-slip normal faults.\ud Neither normal nor oblique-slip normal faults show any relationship with the geometry of the paleoslope.\ud The results obtained from this study may help the interpretation of subsurface data in those\ud geological contexts in which the interplay of gravitational and tectonic processes is responsible for\ud deformation
Submarine mass‐transport deposits represent important stratigraphic heterogeneities within slope and basinal sedimentary successions. A poor understanding of how their distribution and internal architecture affect the fluid flow migration pathway may lead to unexpected compartmentalization issues in reservoir analysis. Studies of modern carbonate mass‐transport deposits mainly focus on large seismic‐scale slope failures; however, the near‐platform basinal depositional environment often hosts mass‐transport deposits of various dimensions. The small‐scale and meso‐scale (metres to several tens of metres) carbonate mass‐transport deposits play a considerable role in distribution of sediment and therefore have an impact on the heterogeneity of the succession. In order to further constrain the geometry and internal architecture of mass‐transport deposits developed in near‐slope basinal carbonates, a structural and sedimentological analysis of sub‐seismic‐scale mass‐transport deposits has been undertaken on the eastern margin of the Apulian carbonate platform in the Gargano Promontory, south‐east Italy. These mass‐transport deposits, that locally comprise a large proportion (50 to 60%) of the base of slope to basinal sediments of the Cretaceous Maiolica Formation, typically display a vertically bipartite character, including debrites and slump deposits of varying volume ratios. A range of brittle and ductile deformation styles developed within distinct bed packages, together with the presence of both chert clasts, folded chert layers and spherical chert nodules, suggest that sediments were at different stages of lithification prior to downslope movement associated with mass‐transport deposits. This study helps elucidate the emplacement processes, frequency and character of subseismic‐scale mass‐transport deposits within the basinal carbonate environment, and thereby reduces the uncertainties in the characterization of subsurface carbonate geofluid reservoirs.
A detailed characterisation of submarine mass-transport deposits (MTDs), in terms of both emplacement processes and internal architecture of depositional products, is crucial to define the hydraulic properties of slope-to-basinal deposits. The Late Jurassic-Early Cretaceous basinal Maiolica Formation exposed in the Gargano Promontory (southern Italy) represents an ideal natural laboratory to study the complex stratigraphic architecture of ancient MTDs. This formation consists of undisturbed intervals of flat-lying, thin-bedded, cherty micritic limestone interbedded with intervals of lithologically similar, but chaotic strata that are characterized by significant internal distortion. The stratigraphic thickness of these deformed units, which are interpreted to represent several types of mass movements (e.g., slumps and, to a lesser extent, slides and debris flows), varies from several decimetres to tens of metres.\ud The internal deformation features comprise down-slope verging folds, together with both normal and reverse faults. In several places, the studied MTDs exhibit signs of reworking, as demonstrated by reactivation of the slump-related faults resulting in deformation of beds directly overlying the MTDs. Structural features within MTD’s, provide information about the direction of the mass movement, and hence the orientation of the paleoslope. Measurements in the eastern and north-eastern part of Gargano Promontory suggest flow is directed towards the E and N respectively. The internal architecture of studied MTDs is discussed in the context of triggering mechanisms related to the characteristics of the Cretaceous paleoslope of the Apulian Platform
In the last decade central Italy was struck by devastating seismic sequences resulting in hundreds of casualties (i.e., 2009-L′Aquila moment magnitude [Mw] = 6.3, and 2016-Amatrice-Visso-Norcia Mw max = 6.5). These seismic events were caused by two NW-SE−striking, SW-dipping, seismogenic normal faults that were modeled based on the available focal mechanisms and the seismic moment computed during the relative mainshocks. The seismogenic faults responsible for the 2009-L′Aquila Mw = 6.3 (Paganica Fault—PF) and 2016-Amatrice-Visso-Norcia Mw max = 6.5 (Monte Vettore Fault—MVF) are right-stepping with a negative overlap (i.e., underlap) located at the surface in the Campotosto area. This latter was affected by seismic swarms with magnitude ranging from 5.0 to 5.5 during the 2009 seismic sequence and then in 2017 (i.e., a few months later than the mainshocks related with the 2016 seismic sequence). In this paper, the seismogenic faults related to the main seismic events that occurred in the Campotosto Seismic Zone (CSZ) were modeled and interpreted as a linkage fault zone between the PF and MVF interacting seismogenic faults. Based on the underlap dimension, the seismogenic potential of the CSZ is in the order of Mw = 6.0, even in the case that all the faults belonging to the zone were activated simultaneously. This has important implications for seismic hazard assessment in an area dominated by the occurrence of a major NW-SE−striking extensional structure, i.e., the Monte Gorzano Fault (MGF). Mainly due to its geomorphologic expression, this fault has been considered as an active and silent structure (therefore representing a seismic gap) able to generate an earthquake of Mw max = 6.5−7.0. However, the geological evidence provided with this study suggests that the MGF is of early (i.e., pre- to syn-thrusting) origin. Therefore, the evaluation of the seismic hazard in the Campotosto area should not be based on the geometrical characteristics of the outcropping MGF. This also generates substantial issues with earthquake geological studies carried out prior to the recent seismic events in central Italy. More in general, the 4-D high-resolution image of a crustal volume hosting an active linkage zone between two large seismogenic structures provides new insights into the behavior of interacting faults in the incipient stages of connection.
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