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The W Po Plain (Northern Italy) is commonly regarded as a region characterized by a low seismicity hazard, due to the lack of historical and instrumental record of strong earthquakes. Nevertheless, recent studies performed in the Monferrato hills provide evidence of active faulting and possible paleoseismicity occurred in Middle Pleistocene to Holocene times. Therefore, for verifying the seismic potential of this area, we firstly revised the available geological and geophysical information. We selected the area between Valenza and Alessandria (Eastern Monferrato Arc), which show the best structural, geomorphic, and stratigraphic setting for documenting recent tectonic deformation and faulting. Therein, we identified, for the first time, evidence for earthquake surface displacement in a Late Quaternary pedosedimentary sequence exposed at Pecetto di Valenza. The outcropping section has been logged and investigated according to an approach integrating sedimentological and micropedological data with structural analyses and radiocarbon dating. This allowed reconstructing the recent surface evolution and the paleoseismic history of the site. From the bottom, the pedosedimentary sequence consists of a Miocene marly bedrock, whose weathering started in Marine Isotopic Stage (MIS) 7 or 5 interglacials. A colluvial deposit follows, whose formation can be attributed to MIS 5e. The upper part of the sequence consists of two loess covers, showing different degrees of weathering, possibly occurred at ca. 30 ka BP for the deepest loess and in the Middle Holocene (ca. 4 ka BP) for the uppermost one. The loess accretion is therefore older and likely associated to the MIS 3 and MIS 2 glacial phases. Each deposit records the deformation induced by earthquake surface reverse faulting and warping, giving constraints to the sequence of events that characterized this site. In fact, the structural analyses and a 2D balanced retrodeformation of the section, integrating pedostratigraphic constraints, allowed identifying at least two different phases of deformation, and more than five fault scarp-forming events, which caused a total net displacement of ca. 4.8 m during the past ca. 40 ka. Our approach highlighted the interaction between the tectonically induced surface deformation and the aeolian deposition, allowing reconstructing the recent evolution of a small drainage basin. The results of this paleoseismic analysis reinforce the conclusion of previous Authors that the Monferrato Arc should be viewed as a seismic gap, characterized by strong earthquakes (Mmax ∼6.5) with long recurrence interval (in the order of several thousands years). This evidence has relevant implications for seismic hazard assessment, which must be checked with further trench investigations along the mapped Quaternary thrust faults affecting the western part of the Po Plain. [ABSTRACT FROM AUTHOR]

Poster: Clinical track: Prostate PO-1204: Clinical outcomes and prognostic factors in patients with localized prostate cancer treated HDR BT D. Delishaj, C.P. Soatti, C. Frigerio, R. D'amico, F. Bonsignore, I.C. Fumagalli, G. De Nobili, A. Cocchi, A. Vola, G. Sangalli, F. Declich, A. Colombo. [Extracted from the article]

The fabric of reverse fault zones close to the surface is usually partitioned in between a narrow discrete rupture zone and a more distributed one, where folding is predominant. This makes quite challenging the adoption of proper setbacks in surface rupture hazard studies for critical facilities or microzoning. Some of the parameters controlling fault zone fabric are related to mechanics of near-surface geology (lithology, overburden thickness, cohesion and water content) whose interaction is complex and only partially understood. Nevertheless, these can be seldom measured or derived. Kinematic models, conversely, express such an interaction of complex variables as simple synthetic parameters, such as the amount of upward propagation of the fault tip for unit of slip, usually referred to as the P/S ratio (Propagation on Slip). Here, we discuss results on the trishear kinematic inverse modeling of a contractional fault propagation fold at Monte Netto Hill (Capriano del Colle, N. Italy), observing a two-stage fault and fold growth evolution, marked by a significant shift in the P/S parameter. At this site, exceptional sequence of exposures due to ca. 10 years of quarry excavations allowed to obtain a series of cross-sections across the fault zone. We use this detailed, high-resolution, example as a natural "analogue" for more general, large-scale surface ruptures involving a thick alluvial cover, a very common setting for the siting of critical facilities. During the early stage of displacement, the fault cut through clast-supported fluvial gravels with a high propagation rate (P/S = 7) and a discrete rupture width. Then, during the latest movements of the thrust, fault tip propagation slowed down to P/S ≈ 2.9, as the fault started cutting through several stacked bodies of clays and silty clays, pedogenized aeolian silts and overbank deposits, causing a pronounced folding of the layers over a wider deformation zone. These results strongly suggest that lithological changes in the underlying shallow stratigraphy, common in an alluvial plain depositional setting, would significantly affect the potential for surface faulting across the same tectonic structure, with relevant implications in the fault displacement hazard assessment. • Trishear progressive restoration of a break-through fault-propagation fold highlighted the halving of P/S through time. • Vertical lithological changes determined the speed of propagation of the fault tip through the overlying sedimentary cover. • FDHA should incorporate results from kinematic models for predicting the likelihood of ground breaking. [ABSTRACT FROM AUTHOR]

Understanding the transformations of the climate system may help to predict and reduce the effects of global climate change. The geological record provides a unique archive that documents the long-term fluctuations of environmental variables, such as seasonal change. Here, we investigate how seasonal variation in seawater temperatures varied in the Mediterranean Sea during the early Pleistocene, approaching the Early-Middle Pleistocene Transition (EMPT) and the beginning of precession-driven Quaternary-style glacial–interglacial cycles. We performed whole-shell and sclerochemical stable isotope analyses (δ 18 O, δ 13 C) on bivalves, collected from the lower Pleistocene Arda River marine succession (northern Italy), after checking shell preservation. Our results indicate that seawater temperature seasonality was the main variable of climate change in the Mediterranean area during the early Pleistocene, with the Northern Hemisphere Glaciation (NHG) exerting a control on the Mediterranean climate. We show that strong seasonality (14.4–16.0 °C range) and low winter paleotemperatures (0.8–1.6 °C) were likely the triggers leading to the establishment of widespread populations of so called “northern guests” (i.e., cold water taxa) in the Mediterranean Sea around 1.80 Ma. The shells postdating the arrival of the “northern guests” record a return to lower seasonal variations and higher seawater paleotemperatures, with seasonality increasing again approaching the EMPT; the latter, however, is not associated with a corresponding cooling of mean seawater paleotemperatures, showing that the observed seasonality variation represents a clear signal of progressive climate change in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]