Slip-rates of blind thrusts in slow deforming areas: examples from the Po Plain (Italy)

We calculate Plio-Pleistocene slip rates on the blind thrusts of the outer Northern Apennines fronts, that are the potential sources of highly damaging earthquakes, as shown by the MW 6.1-6.0, 2012 Emilia-Romagna seismic sequence. Slip rates are a key parameter for understanding the seismogenic potential of active fault systems and assessing the seismic hazard they pose, however, they are difficult to calculate in slow deforming areas like the Po Plain where faulting and folding is mostly blind. To overcome this, we developed a workflow which included the preparation of a homogeneous regional dataset of geological and geophysical subsurface information, rich in Plio- Pleistocene data. We then constructed 3D geological models around selected individual structures to decompact the clastic units and restore the slip on the fault planes. The back-stripping of the differential compaction eliminates unwanted overestimation of the slip rates due to compactioninduced differential subsidence. Finally, to restore the displacement we used different methods according to the deformation style, i.e. Fault Parallel Flow for faulted horizons, trishear and elastic dislocation modeling for fault-propagation folds. The result of our study is the compilation of a slip rate database integrating former published values with 28 new values covering a time interval from the Pliocene to the present. It contains data on 14 individual blind thrusts including the Mirandola thrust, seismogenic source of the 29 May 2012, MW 6.0 earthquake. Our study highlights that the investigated thrusts were active with rates ranging between 0.1-1.0 mm/yr during the last 1.81 Myr. The Mirandola thrust slipped at 0.86±0.38 mm/yr during the last 0.4 Myr. These rates calculated with an homogeneous methodology through the entire Po Plain can be charged entirely to the thrust activity and not to secondary effects like the differential compaction of sediments across the structures

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

Deliverable # 3.01.2 Slip rate data of seismogenic sources included in DISS

This deliverable contains three different products: one table with reclassified slip rate data from DISS, one table with slip rate values calculated from numerical models, and two study cases that illustrate the applications of original methods to estimate slip rate

Preface: Geology and information technology

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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

The Geology of the Periadriatic basin and of the Adriatic Sea

[No abstract available