Deriving thrust fault slip rates from geological modeling: examples from the Marche coastal and offshore contraction belt, Northern Apennines, Italy.

We present a reconstruction of the central Marche thrust system in the central-northern Adriatic domain aimed at constraining the geometry of the active faults deemed to be potential sources of moderate to large earthquakes in this region and at evaluating their long-term slip rates. This system of contractional structures is associated with fault-propagation folds outcropping along the coast or buried in the offshore that have been active at least since about 3Myr. The ongoing deformation of the coastal and offshore Marche thrust system is associated with moderate historical and instrumental seismicity and recorded in sedimentary and geomorphic features. In this study, we use subsurface data coming from both published and original sources. These comprise cross-sections, seismic lines, subsurface maps and borehole data to constrain geometrically coherent local 3D geological models, with particular focus on the Pliocene and Pleistocene units. Two sections crossing five main faults and correlative anticlines are extracted to calculate slip rates on the driving thrust faults. Our slip rate calculation procedure includes a) the assessment of the onset time which is based on the sedimentary and structural architecture, b) the decompaction of clastic units where necessary, and c) the restoration of the slip on the fault planes. The assessment of the differential compaction history of clastic rocks eliminates the effects of compaction-induced subsidence which determine unwanted overestimation of slip rates. To restore the displacement along the analyzed structures, we use two different methods on the basis of the deformation style: the fault parallel flow algorithm for faulted horizons and the trishear algorithm for fault-propagation folds. The time of fault onset ranges between 5.3-2.2 Myr; overall the average slip rates of the various thrusts are in the range of 0.26-1.35 mm/yr

Abnormal foot function in diabetic patients: the altered onset of Windlass mechanism

Aim The aim of this study was to examine foot function in the presence of diabetes-induced alterations of the anatomical and biomechanical unit formed by the Achilles tendon, plantar fascia and metatarso-phalangeal joints. More specifically, we focused on the Windlass mechanism, the physiological mechanism which entails stiffening of the foot during propulsion. Methods Sixty-one diabetic patients, with or without neuropathy, and 21 healthy volunteers were recruited. The thickness of Achilles tendon and plantar fascia was measured by ultrasound. The main biomechanical parameters of foot-floor interaction during gait were acquired by means of dedicated platforms. The range of motion of the 1st metatarso-phalangeal joint was measured passively. Results The plantar fascia (PF) and Achilles tendon (AT) were significantly thickened in diabetic patients [control subjects: PF 2.0 +/- 0.5 mm, AT 4.0 +/- 0.5 mm; diabetic patients without neuropathy: PF 2.9 +/- 1.2 mm (P = 0.002), AT 4.6 +/- 1.0 mm (P = 0.016); diabetic patients with neuropathy: PF 3.0 +/- 0.8 mm (P < 0.0001), AT 4.9 +/- 1.7 mm (P = 0.026)]. Joint mobility was significantly reduced [control subjects: 100.0 +/- 10.0 degrees; diabetic patients without neuropathy: 54.0 +/- 29.4 degrees (P < 0.0001); diabetic patients with neuropathy: 54.9 +/- 17.2 degrees (P < 0.0001)]. Loading times and force integrals under the heel and the metatarsals increased [metatarsal loading time (% stance phase): control subjects 88.2 +/- 4.1%; diabetic patients without neuropathy 90.1 +/- 4.7% (P = 0.146); diabetic patients with neuropathy 91.7 +/- 6.6% (P = 0.048)]. Conclusions Increased thickness of Achilles tendon and plantar fascia, more evident in the presence of neuropathy, may contribute to an overall increase of tensile force and to the occurrence of an early Windlass mechanism, maintained throughout the whole gait cycle. This might play a significant role in the overall alteration of the biomechanics of the foot-ankle complex

Does the thickening of Achilles tendon and plantar fascia contribute to the alteration of diabetic foot loading?

Background. The diabetic foot often undergoes abnormal plantar pressures, changing in walking strategy, ulcerative processes. The present study focuses on the effects that diabetes-induced alterations of Achilles tendon, plantar fascia and first metatarsophalangeal joint-both anatomical and functional-may have on foot loading. Methods. Sixty-one diabetic patients, with or without neuropathy, and 21 healthy volunteers were recruited. Thickness of Achilles tendon and plantar fascia was measured by ultrasound. Flexion-extension of the first metatarso-phalangeal joint was measured passively. Main biomechanic parameters of foot floor interaction during gait were acquired and related to the above measurements. Findings. Plantar fascia and Achilles tendon were significantly (P < 0.05) thicker in diabetics than in controls; mean values (SD) for controls, diabetics without and with neuropathy were 2.0 mm (0.5), 2.9 mm (1.2) and 3.0 mm (0.8) for plantar fascia, respectively, and 4.0 mm (0.5), 4.6 mm (1.0) and 4.9 mm (1.7) for Achilles tendon, respectively. Flexion-extension of the first metatarso-phalangeal joint was significantly (P < 0.05) smaller in diabetics than in controls; mean values (SD) for controls, diabetics without and with neuropathy were 100.0&DEG; (10.0), 54.0&DEG; (29.4) and 54.9&DEG; (17.2), respectively. The increase in the vertical force under the metatarsals was strongly related (R = 0.83, explained variance = 70.1%) to the changes in the three above parameters. Interpretation. Thickening of plantar fascia and Achilles tendon in diabetics, more evident in the presence of neuropathy, concurs to develop a rigid foot, which poorly absorbs shock during landing (performs the physiological impact force absorption during landing). More generally, an overall alteration of the foot-ankle complex motion likely occurs throughout the whole gait cycle, which partly explains the abnormal loading under the forefoot. © 2005 Elsevier Ltd. All rights reserved

Muscle performance and ankle joint mobility in long-term patients with diabetes

Background: Long-term patients with diabetes and peripheral neuropathy show altered foot biomechanics and abnormal foot loading. This study aimed at assessing muscle performance and ankle mobility in such patients under controlled conditions. Methods: Forty six long-term diabetes patients with (DN) and without (D) peripheral neuropathy, and 21 controls (C) were examined. Lower leg muscle performance and ankle mobility were assessed by means of a dedicated equipment, with the patient seated and the examined limb unloaded. 3D active ranges of motion and moments of force were recorded, the latter during maximal isometric contractions, with the foot blocked in different positions. Results: All patients showed reduced ankle mobility. In the sagittal and transversal planes reduction vs C was 11% and 20% for D, 20% and 21% for DN, respectively. Dorsal-flexing moments were significantly reduced in all patients and foot positions, the highest reduction being 28% for D and 37% for DN. Reductions of plantar-flexing moments were in the range 12-15% for D (only with the foot blocked in neutral and in dorsal-flexed position), and in the range 10-24% for DN. In all patients, reductions in the frontal and transversal planes ranged 14-41%. Conclusion: The investigation revealed ankle functional impairments in patients with diabetes, with or without neuropathy, thus suggesting that other mechanisms besides neuropathy might contribute to alter foot-ankle biomechanics. Such impairments may then play a role in the development of abnormal gait and in the onset of plantar ulcers

Integration of geodetic observations and geological models for investigating the permanent component of land subsidence in the Po Delta (northern Italy)

Defining land subsidence causes is not an easy task, because ground lowering is a complex phenomenon due to the contribution of different physical processes related to natural contest and to anthropic actions. Indeed, such processes, which are characterized by a specific origin and may act in different spatial and temporal intervals, can overlap giving rise to a single surface land deformation, observable through conventional and innovative monitoring techniques (i.e. high-precision levelling, InSAR and GNSS). Of course, discriminating the individual causes is fundamental for reducing environmental and social harms, especially in deltas and coastal areas, where land sinking, coupled with climatic effects, can induce massive flooding. The present work concerns an application of a multi-component and multi-source approach, recently proposed by some of the authors for studying land subsidence in deltas. Such a methodology is aimed at understanding the processes causing both periodic and permanent components of the vertical land movement and at retrieving more accurate subsidence rates. It consists of three steps, respectively involving: a component recognition phase, based on statistical and spectral analyses of geodetic time series; a source (or physical process) selection phase, based on the comparison with data of different nature; a source validation step, where the selected sources are validated through physically-based models. The proposed procedure has been applied to the permanent component of subsidence in the Po Delta (northern Italy), an area historically affected by land subsidence and influenced by climatic changes, where continuous GNSS data and differential InSAR-derived time series were simultaneously acquired from 2012 to 2017. In particular, the exponential relation found between the mean SAR-derived LOS velocity and the thickness of the Late Holocene prograding deposits, pointed out the key role of the sedimentary compaction process with respect to the spatial distribution of the subsidence rates and confirmed the importance, already highlighted by other authors, of the consolidation of the shallower strata. In order to validate the consolidation process and to quantify also the deeper contributions of tectonics- and isostasy-depending mechanisms, 2D geological models have been constructed along two west-east sections across the central part of the Delta. Finally, the computed subsidence rates have been compared with the geodetic velocities estimated in Taglio di Po and Porto Tolle villages (Rovigo, northern Italy), clarifying the contribution of each geological mechanism to the observed delta subsidence

Challenges of Anthropocene and the role of Landscape Ecology - Le sfide dell'Antropocene e il ruolo dell'Ecologia del Paesaggio - Atti del Congresso Scientifico SIEP-IALE, Asti, 26/27/28 maggio 2016

Gli atti riportano i contributi del Congresso che ha voluto riflettere da un lato sui quadri interpretativi e metodologici capaci di comprendere e descrivere la complessità dei fenomeni dell’Antropocene e dall’altro avviare un rinnovato dibattito sulle risposte che, in prima battuta come persone, siamo chiamati a sviluppare e mettere in campo per garantire scenari migliorativi, adattivi e orientati a processi di riequilibrio tra Uomo e Terra