Search

This work investigates element mobility and deformation mechanisms in sulphide-bearing quartz veins associated with a strike-slip fault exposed in the ONKALO™ Finnish deep repository for spent nuclear fuel (Olkiluoto Island, southwest Finland). It combines petrography, trace element mapping by Laser Ablation Inductively Coupled Plasma Time-of-Flight Mass Spectrometry (LA-ICP-TOFMS) and Electron Backscattered Diffraction (EBSD) analysis of representative microstructures. The fault core was reactivated by brittle deformation episodes assisted by hydrothermal fluid batches with distinct trace element signatures. LA-ICP-TOFMS element distribution maps and EBSD on sulphides reveal local, syn-deformational intragrain enrichment of primary and secondary elements (i.e., As, Co, Cu, Ag, Sn, Sb, Pb, Se, In, Te). Trace element enrichments occur by a combination of microscale plastic distortions and microfracturing at the reaction fronts. Fluid ingress along microcracks enhanced chemical replacement of pyrite that combined with element diffusion along dislocations and tilt boundaries controlled trace element mobility in sulphides at the small scale. At the scale of the vein system, the competence contrast between inclusions of soft sulphides in the harder host quartz may have favored local fracture nucleation and fluid flow.

The traditional study of palaeoseismic trenches, involving logging, stratigraphic and structural interpretation, can be time consuming and affected by biases and inaccuracies. To overcome these limitations, a new workflow is presented that integrates infrared hyperspectral and photogrammetric data to support field-based palaeoseismic observations. As a case study, this method is applied on two palaeoseismic trenches excavated across a post-glacial fault scarp in northern Finnish Lapland. The hyperspectral imagery (HSI) is geometrically and radiometrically corrected, processed using established image processing algorithms and machine learning approaches, and co-registered to a structure-from-motion point cloud. HSI-enhanced virtual outcrop models are a useful complement to palaeoseismic field studies as they not only provide an intuitive visualisation of the outcrop and a versatile data archive, but also enable an unbiased assessment of the mineralogical composition of lithologic units and a semi-automatic delineation of contacts and deformational structures in a 3D virtual environment. R��sum�� L'��tude traditionnelle des tranch��es pal��osismiques, impliquant l'enregistrement des coupes et l'interpr��tation stratigraphique et structurelle, peut prendre beaucoup de temps et ��tre entach��e de biais et d'inexactitudes. Pour surmonter ces limites, une nouvelle m��thodologie est pr��sent��e, int��grant des donn��es photogramm��triques et hyperspectrales infrarouges en appui aux observations pal��osismiques de terrain. Comme ��tude de cas, cette m��thode est appliqu��e �� deux tranch��es pal��osismiques creus��es �� travers un escarpement de faille post-glaciaire dans le nord de la Laponie finlandaise. L'imagerie hyperspectrale (HSI) est corrig��e g��om��triquement et radiom��triquement, trait��e �� l'aide d'algorithmes classiques de traitement d'images et d'apprentissage machine, et recal��e sur un nuage de points photogramm��trique. Les mod��les virtuels d'affleurements am��lior��s par HSI constituent un compl��ment utile aux ��tudes pal��osismiques de terrain, car ils fournissent non seulement une visualisation intuitive de l'affleurement et une archive de donn��es facile d'emploi, mais permettent ��galement une ��valuation non biais��e de la composition min��ralogique d'unit��s lithologiques ainsi qu'une d��limitation semi-automatique des contacts et des structures de d��formation dans un environnement virtuel 3D.

We present the results of geological and structural investigation documenting the interaction between hydrothermal fluids and host rock leading to a vein-type ore mineralization at shallow crustal depths (< 7 km) in the mining district of the eastern Island of Elba (Italy). Sulfide- and iron-rich veins and breccia in addition to minor massive iron-ore bodies form the mineralized system. Structural mapping and analysis of vein systems, fractures, faults and associated fault rocks as well as fracture opening modes show that the main factors controlling the formation and distribution of the mineralization are lithology, deformation style and deformation intensity. Their interplay led to a positive feedback between the evolution of pore pressure through time, strain localization and the resulting mineralization. Inversion of fault and vein data defines an E-W extensional stress field at the time of faulting, which favoured fluid ingress and pervasive flow within the porous host sandstone, interstitial sulfide precipitation and reduction of the primary bulk porosity. Subsequently, cyclic channelized fluid flow during repeated fluid ingresses caused extensive veining and numerous episodes of breccia formation.

An analysis of high-resolution LiDAR-based digital elevation models (DEMs), trenching of Quaternary deposits, diamond drilling and a structural analysis of the bedrock were conducted in order to characterise the geological structure and to derive full slip profiles of the Venejarvi–Jauhojarvi postglacial fault complex located in northern Finland. The Venejarvi-Jauhojarvi fault complex consists of 17 surface ruptures striking in a SW–NE direction, cutting through Late Weichselian till and traceable for a total distance of 29.9 km. Based on stratigraphical and structural analysis we show that the Naamivitikko fault segment, which is part of the Venejarvi–Jauhojarvi complex, hosted up to three distinct slip events and it is therefore argued that the prevailing single-rupture hypothesis of postglacial faults should be treated with caution. Based on the measured surface rupture dimensions, it is conservatively estimated that the maximum moment magnitude of the paleoseismic event that the complex hosted, ranged between Mw ≈ 5.8–8.4. If uncertainties in the scaling laws equating surface rupture dimensions to moment magnitudes are accounted for, a more realistic maximum moment magnitude range between Mw ≈ 5.8–7.6 is given.

The Suasselka fault complex is recognized from high-resolution digital elevation models (LiDAR DEMs) as a complex of 37 surface ruptures striking SW–NE and cutting through Weichselian glacial sediments, confirming the postglacial nature of the rupturing event. The analysis of LiDAR DEMs, geophysical profiles and trenching of glacial sediments at two sites along the Suasselka postglacial fault (PGF) system has provided evidence of earthquakes that post- and predate the Late Weichselian deglaciation. At the Suaspalo trenching site, at least two different rupture events are observed: the first one predates the deposition of the lowermost till unit and potentially dates to the Early or even pre-Weichselian. The second rupture event, on the other hand, deforms overlying tills and is thus a post-Weichselian event. Our results indicate that multiple rupturing events can take place within ‘postglacial fault complexes’, which is the second time such a characteristic has been proven for PGFs in northern Fennoscandia. Furthermore, the present results provide the first evidence of either Early or even pre-Weichselian faulting in Finland, suggesting that the same fault complexes were also active after glacial phases that predated the last glacial maximum of the Late Weichselian. These results warrant re-evaluation of the long-term seismic risk associated with the faults as the assumption of single rupture events is erroneous. Considering that the Suasselka PGF complex is composed of four PGF systems and 37 isolated 150–7500-m-long segments, we calculated the potential moment magnitudes based on the rupture length and mean/maximum vertical displacement for each individual segment and system, taken that they potentially ruptured independently, and finally for the entire Suasselka PGF complex. For the entire complex rupturing in a single event, the observed displacement and length of the complex yields a moment magnitude estimate of Mw ≈ 6.7–8.1. However, based on geomorphological and sedimentological evidence, we believe that this is a conservative estimate of the moment magnitude of the paleoearthquake. If isolated PGF systems are considered to have ruptured individually, the moment magnitudes estimated based on surface rupture lengths range from Mw ≈ 5.5–6.7, and based on mean and maximum cumulative displacement values, the estimated values range from Mw ≈ 6.2–7.3 and Mw ≈ 6.7–8.0, respectively. As we cannot with the available data distinguish the exact number of events, the age of events or which segments potentially ruptured at the same time, we conclude that the events that took place in the complex ranged in moment magnitude from c. Mw ≈ 5.5 to 8.1, the Mw ≈ 8.1 estimate representing conservative upper bound for the maximum moment magnitude.

The ages and sizes of landslides occurring in seismically active areas can be used to reconstruct the seismic history of the area and estimate the maximum moment magnitudes of past earthquakes. Here, we present a data set of 121 landslides discovered in northern Finland that were analyzed for their morphometric characteristics. We show that 89 debris slide type landslides in the data set are clustered close to known postglacial faults (PGFs) and thus provide information on the characteristics of postglacial paleoseismic events. By using empirical correlations between the landslide volume–area data and earthquake moment magnitude, we estimate maximum moment magnitudes M w ≈ 6.9–7.7 for postglacial earthquakes in the Suasselka, Isovaara–Riikonkumpu, Venejarvi, and Vaalajarvi areas, where earlier estimates based on fault length and displacement have yielded magnitudes varying between M w ≈ 6.5 and 7.5. We also show that the landslides in northern Finland are located within a radius of 35 km from the closest known PGF and that sizes of the landslides decrease as a function of distance from PGFs, hence providing strong empirical evidence for their seismic origin. As far as we are aware, this is the first use of landside data in quantifying postglacial seismicity within the Fennoscandian Shield area.

Postglacial faults (PGFs) are common SW-NE-trending features in the northern part of the Fennoscandian shield being attributed to former high-magnitude (Mw ≈ 7–8.2) earthquakes (Arvidsson, 1996). These are of interest for the long-term seismic hazard of deep geological nuclear waste repositories. The PGFs are still seismically active; and many of the deformation features, such as paleolandslides, are spatially coextensive within these earthquake zones. Based on the 14C-datings of landslide-buried organic materials, three postglacial seismic episodes (≈9.7–11, ≈5–6, and 1.3–1.8 ky ago) have been found in western Finnish Lapland. Because the model predictions by Wu et al. (1999) suggested that the onset of fault instability started at 15 ky and that the maximum fault instability was reached at 13–10 ky in Fennoscandia, we postulate that not only subaerial but also subglacial types of deformations may have been associated with the past seismic events. Here, we present LiDAR DEM observations and sediment electromagnetic anisotropy data on the landforms, such as the rim-ridged/arcuate Pulju moraine (Kujansuu, 1967), roundish (liquefaction) bowls, postdepositional (liquefaction) deformations on streamlined landforms, as well as hummocky ridge fields of massflow sediments. The sediments in the Pulju moraine and massflow ridges displayed clear anisotropy, indicating lateral transportation in subglacial wet-based environment. Instead, sediments in the bowl-shaped morphologies next to PGFs and deformed ice-stream flutings tended to be isotropic, suggesting postdepositional and vertical liquefaction processes. Based on the LiDAR morphology and sedimentary anisotropy data, these landforms may be linked to past earthquakes.

BackgroundGait analysis with accelerometers is a relatively inexpensive and easy to use method to potentially support clinical diagnoses of Alzheimer’s Disease and other dementias. It is not clear however, which gait features are most informative and how these measures relate to Alzheimer pathology. In this study, we used in-depth evaluation of gait in cognitively normal (CN) subjects, Mild Cognitive Impairment (MCI) patients, and dementia patients. We evaluated the associations between dynamics of gait, level of cognitive impairment and CSF biomarkers of Alzheimer’s pathology.MethodWe included CN participants (n=58), MCI patients (n=58) and participants with different types of dementia (n=26) of the multicenter PredictND cohort. Participants performed gait tests in two conditions: a normal walk task and a cognitively complex dual task. Gait was measured using tri-axial accelerometers attached to the fifth lumbar vertebra (L5). Following principal component analysis, calculated gait features were clustered into four domains: pace, rhythm, time variability and length variability. Associations between gait domains, clinical diagnosis and CSF biomarkers (Aβ42, total tau, pTau) were examined using linear mixed models, included an interaction term with condition (normal and dual walk task) and were corrected for age, sex and center.ResultDementia patients showed gait disturbances in the pace domain (pConclusionThese findings suggest that gait disturbances increase with level of syndrome diagnosis. Moreover, rhythm disturbances increase with higher levels of CSF total tau and pTau, providing evidence for a direct link with neurodegeneration. These results demonstrate that in-depth gait analysis with accelerometers might be a potential helpful tool to support clinical diagnosis or can be used as clinical outcome tool in clinical trials.

The fact that inherited fault systems show strong variability in their 3D shape provides good reasons to consider the strength of the Earth’s brittle crust as variably anisotropic. In this work we quantify this strength anisotropy as a function of fault system complexity by combining 3D boundary element model, frictional slip theory and fast iterative computation method. This method allows to analyze together a very large number of scenarios of stress and fault mechanical properties variations through space and time. Using both synthetic and real fault system geometries we analyze a very large number of numerical simulations (125,000) to define for the first time macroscopic rupture envelopes for fault systems, referred to as “fault slip envelopes”. Fault slip envelopes are defined using variable friction, cohesion and stress state, and their shape is directly related to the fault system 3D geometry and the friction coefficient on fault surfaces. The obtained fault slip envelopes shows that very complex fault geometry implies low and isotropic strength of the fault system compared to geometry having limited fault orientations relative to the remote stresses, providing strong strength anisotropy. This technique is applied to the realistic geological conditions of the Olkiluoto high-level nuclear waste repository (Finland). The model results suggests that Olkiluoto fault system has a better probability to slip under the present day Andersonian thrust stress regime, than for the strike-slip and normal stress regimes expected in the future due to the probable presence of an ice sheet. This new tool allows to quantify the anisotropy of strength and probability of slip of 3D real fault networks as a function of a wide range of possible geological conditions an mechanical properties. This significantly helps to define the most conservative fault slip hazard case or to account for potential uncertainties in the input data for slip. This technique therefore applies to earthquakes hazard studies, geological storage, geothermal resources along faults and fault leaks/seals in geological reservoirs.

Fluids play a key role in weakening rocks, controlling crustal deformation from early fracture development to mature strain localization, fault nucleation and propagation through cumulative slip. In particular, at the brittle-ductile transition zone crustal deformation and fluid flow are mutually interconnected by repeating cycles of transient frictional and viscous deformation. Uncertainties remain, however, on the details of the micromechanical and chemical influence of fluids in facilitating strain localization processes.N-S to NW-SE sub-vertical brittle-ductile faults cut across the Paleoproterozoic migmatitic basement of southwestern Finland on the island of Olkiluoto, where the Finnish authorities plan the construction of a deep repository for high-grade nuclear waste. The faults are characterized by a brittle–ductile to fully brittle deformation style resulting from transient fluid pressurization. We investigated a representative fault by combining field and microstructural observations with fluid inclusion and mineral chemistry analysis on synkinematic and authigenic minerals in order to reconstruct the temporal variations of pressure, temperature, composition and salinity of the synkinematic fluids that controlled strain localization. Combined laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) and electron back-scattered diffraction analysis (EBSD) were also applied on authigenic sulphides to gain insights into their role upon strain accommodation and deformation-induced elemental transport and distribution at the microscopic scale.Initial embrittlement of the Olkiluoto basement occurred under a first event of fluid overpressure conditions (> 210 MPa) with formation of a diffuse network of joints and/or hybrid–shear fractures in a volume that corresponds to the fault damage zone. Subsequent deformation was caused by repeated hydrofracturing induced by fluid pressure up to 210 MPa. Brittle ruptures affected a system that was otherwise under overall ductile conditions, as demonstrated by mutually overprinting veining, cataclasis and plastic deformation.Later exhumation and cooling of the fault system to fully brittle conditions was aided by reactivation triggered by a distinct fluid ingress at lower pressure (140-180 MPa) and temperature (≤ 300° C). Deformation was accommodated at that stage by the interplay of brittle fracturing and low-temperature crystal-plastic in sulphides. Strain and fluid flow created high diffusivity pathways within the pyrite crystal lattices contributing to- and enhancing the net transport of a significant range of heavy elements (e.g. Co, Ni, Cu, Sn, Ag, As, Sb, Pb). These data indicate that the studied fault zone acted as a chemically open system and fault valve.

BACKGROUND: Gait analysis with accelerometers is a relatively inexpensive and easy to use method to potentially support clinical diagnoses of Alzheimer's disease and other dementias. It is not clear, however, which gait features are most informative and how these measures relate to Alzheimer's disease pathology.OBJECTIVE: In this study, we tested if calculated features of gait 1) differ between cognitively normal subjects (CN), mild cognitive impairment (MCI) patients, and dementia patients, 2) are correlated with cerebrospinal fluid (CSF) biomarkers related to Alzheimer's disease, and 3) predict cognitive decline.METHODS: Gait was measured using tri-axial accelerometers attached to the fifth lumbar vertebra (L5) in 58 CN, 58 MCI, and 26 dementia participants, while performing a walk and dual task. Ten gait features were calculated from the vertical L5 accelerations, following principal component analysis clustered in four domains, namely pace, rhythm, time variability, and length variability. Cognitive decline over time was measured using MMSE, and CSF biomarkers were available in a sub-group.RESULTS: Linear mixed models showed that dementia patients had lower pace scores than MCI patients and CN subjects (p CONCLUSION: These findings suggest that gait - particularly measures related to pace and rhythm - are altered in dementia and have a direct link with measures of neurodegeneration.

Late and postglacial reverse faults and seismically-induced landslides are characteristic features of deglaciated terrain in the northern Fennoscandia. The main focus of this study was to investigate the rupturing history of the reverse Vaalajarvi fault complex in Sodankyla, Finland, based on remote sensing, on-site geophysics and sedimentology in excavations trenched across the faulted terrain. In addition to the previously known NNW–SSE-trending Vaalajarvi segment, we discovered six new SW–NE-trending fault segments that probably belong to the same Vaalajarvi ‘postglacial’ fault complex. Our analysis indicate that the Vaalajarvi fault segment was triggered by stress change caused by ruptures on the surrounding SW–NE-trending reverse faults. In total, at least two to three slip events have taken place in different segments of the Vaalajarvi complex since the Early Weichselian with the most recent event(s) being postglacial in timing. By using the scaling laws of fault surface rupture length and offset and under different scenarios of which segments or systems ruptured in a single or separate event, we estimate that the Vaalajarvi complex potentially hosted an earthquake that ranged between Mw ≈ 6.7–7.0. This magnitude is comparable to the landslide-inferred magnitudes in the Vaalajarvi area.

Soft-sediment deformation structures are preserved in clastic-biogenic varves of the Lake Nurmijarvi sequence from central-southern Finland. Deformation structures include centimeter-scale folding and faulting structures and larger convolute bedding, which are separated from the overlying undisturbed varved section by a turbidite dated at 7400 cal BP. The soft-sediment deformation provides evidence for postglacial seismic activity ca. 3500 years after the deglaciation of the study area. By screening the sizes of potential source faults for the event, the maximum earthquake moment magnitudes associated with the deformation structures were constrained to MW ≈ 5.1–6.9 with realistic 40% rupture scenarios, or up to MW ≈ 5.1–7.7 if more conservative scenarios are considered. The results of the study thus indicate a relatively high-magnitude postglacial seismic event in southern Finland, which adds to the evidence that the postglacial seismic activity was not just restricted to northern Fennoscandia, but was a more widespread phenomenon. The age of the Lake Nurmijarvi seismic event further demonstrates that high-magnitude seismic activity was not restricted to a relatively short period after deglaciation, but the period of high-magnitude postglacial seismic activity was much longer than previously thought. By assessing the orientations of faults that are presently active and using available focal mechanism data, our results suggest that strike-slip faulting may be a more important mechanism for the generation of both present-day and postglacial earthquakes in southern Finland than reverse faulting, which should further be accounted for in the assessment of long-term seismic hazards.

Crustal deformation at the brittle-ductile transition may take place by a combination of competing brittle fracturing and viscous flow processes. This competition may be triggered by variations of properties (e.g., T, P, density) of the fluid hosted by the fault at the time of deformation. Hence, a joint (micro)structural and geochemical approach to the study of the deformation processes and of the assisting fluid phase(s) provides insights into the dynamic evolution of strength in the seismogenic crust. Fault zones in the Olkiluoto nuclear waste disposal site in SW Finland exhibit a mixed brittle-ductile deformation style, and represent excellent targets to study coexisting ductile and brittle deformation in quartz-rich systems. We present results from a fault zone characterized by complex kinematics and reactivation history, as demonstrated by at least two types of synkinematic quartz-chlorite veins (types 1 and 2). Microstructural analysis documents a variety of fully ductile quartz deformation features (WEB’s, bulging and subgrain rotation recrystallization) overprinting and overprinted by mixed brittle-ductile textures (recrystallized cataclasites and healed fractures). Fluid inclusion microthermometry and chlorite geothermometry constrain deformation within the fault to 250-350°C, which is the typical T range defining the greenschist facies metamorphism at the base of the seismogenic crust. We propose that the repeated rheological switches from frictional to viscous deformation mechanisms were controlled by transient and repeated changes of fluid properties. If these variations took place at seismic velocities, the exhumed microstructural record would witness seismic cycles, with type 1 and type 2 veins reflecting discrete failure events during the shocks. The brittle-ductile deformation microstructures would represent instead the interseismic creep.

Analysis of airborne LiDAR-based digital elevation models (DEMs), trenching of Quaternary deposits, and diamond drilling through faulted bedrock was conducted to characterize the geological structure and full slip profiles of the Isovaara–Riikonkumpu postglacial fault (PGF) complex in northern Finland. The PGF systems are recognized from LiDAR DEMs as a complex of surface ruptures striking SW–NE, cutting through late-Weichselian till, and associated with several postglacial landslides within 10 km. Evidence from the terrain rupture characteristics, the deformed and folded structure of late-Weichselian till, and the 14 C age of 11,300 cal BP from buried organic matter underneath the Sotka landslide indicates a postglacial origin of the Riikonkumpu fault (PGF). The fracture frequency and lithology of drill cores and fault geometry in the trench log indicate that the Riikonkumpu PGF dips to WNW with a dip angle of 40–45° at the Riikonkumpu site and close to 60° at the Riikonvaara site. A fault length of 19 km and the mean and maximum cumulative vertical displacement of 1.3 m and 4.1 m, respectively, of the Riikonkumpu PGF system indicate that the fault potentially hosted an earthquake with a moment magnitude M W ≈ 6.7–7.3 assuming that slip was accumulated in one seismic event. Our interpretation further suggests that the Riikonkumpu PGF system is linked to the Isovaara PGF system and that, together, they form a larger Isovaara–Riikonkumpu fault complex. Relationships between the 38-km-long rupture of the Isovaara–Riikonkumpu complex and the fault offset parameters, with cumulative displacement of 1.5 and 8.3 m, respectively, indicate that the earthquake(s) contributing to the PGF complex potentially had a moment magnitude of M W ≈ 6.9–7.5. In order to adequately sample the uncertainty space, the moment magnitude was also estimated for each major segment within the Isovaara–Riikonkumpu PGF complex. These estimates vary roughly between M W ≈ 5–8 for the individual segments.

Background and objective: This study aimed to develop a late-life dementia prediction model using a novel validated supervised machine learning method, the Disease State Index (DSI), in the Finnish population-based CAIDE study. Methods: The CAIDE study was based on previous population-based midlife surveys. CAIDE participants were re-examined twice in late-life, and the first late-life re-examination was used as baseline for the present study. The main study population included 709 cognitively normal subjects at first re-examination who returned to the second re-examination up to 10 years later (incident dementia n = 39). An extended population (n = 1009, incident dementia 151) included non-participants/non-survivors (national registers data). DSI was used to develop a dementia index based on first re-examination assessments. Performance in predicting dementia was assessed as area under the ROC curve (AUC).Results: AUCs for DSI were 0.79 and 0.75 for main and extended populations. Included predictors were cognition, vascular factors, age, subjective memory complaints, and APOE genotype.Conclusion: The supervised machine learning method performed well in identifying comprehensive profiles for predicting dementia development up to 10 years later. DSI could thus be useful for identifying individuals who are most at risk and may benefit from dementia prevention interventions.

Microstructural record of fault rocks active at the brittle ductile transition zone (BDTZ) may retain information on the rheological parameters driving the switch in deformation mode, and on the role of stress and fluid pressure in controlling different fault slip behaviours. In this study we analysed the deformation microstructures of the strike-slip fault zone BFZ045 in Olkiluoto (SW Finland), located in the site of a deep geological repository for nuclear waste. We combined microstructural analysis, electron backscatter diffraction (EBSD), and mineral chemistry data to reconstruct the variations in pressure, temperature, fluid pressure and differential stress that mediated deformation and strain localization along BFZ045 across the BDTZ. BFZ045 exhibits a mixed ductile-brittle deformation, with a narrow (

Background: Idiopathic normal pressure hydrocephalus (iNPH) patients often develop Alzheimer’s disease (AD) related brain pathology. Disease State Index (DSI) is a method to combine data from various sources for differential diagnosis and progression of neurodegenerative disorders. Objective: To apply DSI to predict clinical AD in shunted iNPH-patients in a defined population. Methods: 335 shunted iNPH-patients (median 74 years) were followed until death (n = 185) or 6/2015 (n = 150). DSI model (including symptom profile, onset age of NPH symptoms, atrophy of medial temporal lobe in CT/MRI, cortical brain biopsy finding, and APOE genotype) was applied. Performance of DSI model was evaluated with receiver operating characteristic (ROC) curve analysis. Results: A total of 70 (21%) patients developed clinical AD during median follow-up of 5.3 years. DSI-model predicted clinical AD with moderate effectiveness (AUC = 0.75). Significant factors were cortical biopsy (0.69), clinical symptoms (0.66), and medial temporal lobe atrophy (0.66). Conclusion: We found increased occurrence of clinical AD in previously shunted iNPH patients as compared with general population. DSI supported the prediction of AD. Cortical biopsy during shunt insertion seems indicated for earlier diagnosis of comorbid AD.

By combining 3D boundary element model, frictional slip theory and fast computation method, we propose a new tool to improve fault slip analysis that allows to analyze a very large number of scenarios of stress and fault mechanical properties variations through space and time. Using both synthetic and real fault system geometries we analyze a very large number of numerical simulations (125,000) using fast iterative method to define for the first time macroscopic rupture envelopes for fault systems, referred to as “fault slip envelopes”. Fault slip envelopes are defined using variable friction, cohesion and stress state, and their shape is directly related to the fault system 3D geometry and the friction coefficient on fault surfaces. The obtained fault slip envelopes shows that very complex fault geometry implies low and isotropic strength of the fault system compared to geometry having limited fault orientations relative to the remote stresses, providing strong strength anisotropy. This technique is applied to the realistic geological conditions of the Olkiluoto high-level nuclear waste repository (Finland). The model results suggests that Olkiluoto fault system has a better probability to slip under the present day Andersonian thrust stress regime, than for the strike-slip and normal stress regimes expected in the future due to the probable presence of an ice sheet. This new tool allows to quantify the anisotropy of strength and probability of slip of 3D real fault networks as a function of a wide range of possible geological conditions an mechanical properties. This significantly helps to define the most conservative fault slip hazard case or to account for potential uncertainties in the input data for slip. This technique therefore applies to earthquakes hazard studies, geological storage, geothermal resources along faults and fault leaks/seals in geological reservoirs.

Background We developed multifactorial models for predicting incident dementia and brain pathology in the oldest old using the Vantaa 85+ cohort. Methods We included participants without dementia at baseline and at least 2 years of follow-up (N = 245) for dementia prediction or with autopsy data (N = 163) for pathology. A supervised machine learning method was used for model development, considering sociodemographic, cognitive, clinical, vascular, and lifestyle factors, as well as APOE genotype. Neuropathological assessments included β-amyloid, neurofibrillary tangles and neuritic plaques, cerebral amyloid angiopathy (CAA), macro- and microscopic infarcts, α-synuclein pathology, hippocampal sclerosis, and TDP-43. Results Prediction model performance was evaluated using AUC for 10 × 10-fold cross-validation. Overall AUCs were 0.73 for dementia, 0.64–0.68 for Alzheimer’s disease (AD)- or amyloid-related pathologies, 0.72 for macroinfarcts, and 0.61 for microinfarcts. Predictors for dementia were different from those in previous reports of younger populations; for example, age, sex, and vascular and lifestyle factors were not predictive. Predictors for dementia versus pathology were also different, because cognition and education predicted dementia but not AD- or amyloid-related pathologies. APOE genotype was most consistently present across all models. APOE alleles had a different impact: ε4 did not predict dementia, but it did predict all AD- or amyloid-related pathologies; ε2 predicted dementia, but it was protective against amyloid and neuropathological AD; and ε3ε3 was protective against dementia, neurofibrillary tangles, and CAA. Very few other factors were predictive of pathology. Conclusions Differences between predictors for dementia in younger old versus oldest old populations, as well as for dementia versus pathology, should be considered more carefully in future studies. Electronic supplementary material The online version of this article (10.1186/s13195-018-0450-3) contains supplementary material, which is available to authorized users.

The dynamic evolution of fault zones at the seismogenic brittle-ductile transition zone (BDTZ) expresses the delicate interplay of numerous physical and chemical processes that occur at the time of strain localization. Deformation and flow of aqueous fluids in these zones, in particular, are closely related and mutually dependent during cycles of repeating, transient frictional and viscous deformation. Despite numerous studies documenting in detail seismogenic faults exhumed from the BDTZ, uncertainties remain as to the role of fluids in facilitating deformation in this zone, particularly with regard to the mechanics of broadly coeval brittle and ductile deformation. We combine here structural analysis, fluid inclusion data and mineral chemistry data from synkinematic and authigenic minerals to reconstruct the temporal variations in P, T and bulk composition of the fluids that mediated deformation and steered strain localization in a strike-slip fault from the BDTZ. This is a fault formed within the Paleoproterozoic migmatitic basement of southwestern Finland, hosting in its core two laterally continuous quartz veins formed by two texturally distinct quartz types – Qtz I and Qtz II, where Qtz I is demonstrably older than Qtz II. Veins within the diffuse damage zone of the fault are infilled by Qtz I. Multi-scalar structural analysis indicates recurrent cycles of mutually overprinting brittle and ductile deformation. Fluid inclusion microthermometry and mineral pair geothermometry indicate that both quartz types precipitated from a fluid that was in a homogeneous state during the recurrent cycles of faulting, and whose bulk salinity was in the 0–5 wt % NaCleq range. The temperature of the fluid phase involved with the various episodes of initial strain localization and later reactivation changed with time, from c. 240 °C in the damage zone to c. 350 °C in the core during Qtz I precipitation to Our analysis implies that fluid overpressure at the brittle-ductile transition can play a key role in the initial embrittlment of the metamorphic basement and strain localization mechanisms.

We used drone-acquired orthophotographs to map the 2D-networks of fractures transecting the Mesoproterozoic Rapakivi granites in southern Finland. The work aims at understanding i) how discrete faults and the kinematically linked syn-fault extension fractures originate in crystalline rocks, and ii) how the resulting structural anisotropy controls the patterns of later-formed regional fractures. We recognized incipient faults with associated distinct damage zones (DZ; wall-, tip-, bend- and linking damage) indicating that faulting occurred within mesoscopically isotropic material devoid of pre-existing fabrics. Moreover, fault-induced extension fractures occur also outside the normal DZs indicating much wider DZs than that predicted by scaling laws. Extension fractures within the wide DZs are the result of linkage between sub-parallel segments of the dominantly sinistral and ~N-S trending (sub-) vertical faults. The resulting syn-fault network of N-S, NW-SE and NE-SW trending fracture sets contributed to the mechanical anisotropy that controlled the patterns of the later-formed regional fractures. Specifically, i) narrow fault reactivation damage zones caused deviations in the patterns of otherwise systematic near-orthogonal regional fractures, and ii) the NNW-SSE trending regional fractures are poorly developed in areas where either several N-S faults or sub-parallel NW-SE syn-fault extension fractures are dominant. The latter applies in particular to a large left step-over zone between sinistral faults, which we infer to provide the first-order control over the development of contrasting fracture domains. The results of this study further indicate that a strike-slip paleostress event affected the crust after ca. 1.65 Ga.

Background: Recent criteria allow biomarkers to provide evidence of Alzheimer’s disease (AD) pathophysiology. How they should be implemented in daily practice remains unclear, especially in mild cognitive impairment (MCI) patients. Objective: We evaluated how a clinical decision support system such as the PredictAD tool can aid clinicians to integrate biomarker evidence to support AD diagnosis. Methods: With available data on demographics, cerebrospinal fluid (CSF), and MRI, we trained the PredictAD tool on a reference population of 246 controls and 491 AD patients. We then applied the identified algorithm to 211 MCI patients. For comparison, we also classified patients based on individual biomarkers (MRI; CSF) and the NIA-AA criteria. Progression to dementia was used as outcome measure. Results: After a median follow up of 3 years, 72 (34%) MCI patients remained stable and 139 (66%) progressed to AD. The PredictAD tool assigned a likelihood of underlying AD to each patient (AUC 0.82). Excluding patients with missing data resulted in an AUC of 0.87. According to the NIA-AA criteria, half of the MCI patients had uninformative biomarkers, precluding an assignment of AD likelihood. A minority (41%) was assigned to high or low AD likelihood with good predictive value. The individual biomarkers showed best value for CSF total tau (AUC 0.86). Conclusion: The ability of the PredictAD tool to identify AD pathophysiology was comparable to individual biomarkers. The PredictAD tool has the advantage that it assigns likelihood to all patients, regardless of missing or conflicting data, allowing clinicians to integrate biomarker data in daily practice.

Fault and fracture planes (FFP) that cut through multilayer sequences can be significantly refracted at layer-layer interfaces due to the different mechanical properties of the contiguous layers, such as shear strength, friction coefficient and grain size. Detailed studies of different but coexisting and broadly coeval failure modes (tensile, hybrid and shear) within multilayers deformed in extensional settings have led to infer relatively low confinement and differential stress as the boundary stress conditions at which FFP refraction occurs. Although indeed widely recognized and studied in extensional settings, the details of FFP nucleation, propagation and refraction through multilayers remain not completely understood, partly because of the common lack of geological structures documenting the incipient and intermediate stages of deformation. Here we present the results of a study on strongly refracted strike-slip FFP within the mechanically layered turbidites of the Marnoso Arenacea Formation (MAF) of the Italian Northern Apennines. The MAF is characterized by the alternation of sandstone (strong) and carbonate mudstone (weak) layers. The studied refracted FFP formed at the front of the regional-scale NE-verging Palazzuolo anticline and post-date almost any other observed structure except for a set of late extensional faults. The studied faults display coexistence of shear and hybrid (tensile-shear) failure modes and we suggest that they initially nucleated as shear fractures (mode III) within the weak layers and, only at a later stage, propagated as dilatant fractures (mode I-II) within the strong layers. The tensile fractures within the strong layers invariably contain blocky calcite infills, which are, on the other hand, almost completely absent along the shear fracture planes deforming the weak layers. Paleostress analysis was performed to constrain the NNE-SSW compressional stress field that produced the refracted FFP and to exclude the possibility that the present attitude of these structures may result from the rotation through time of faults with an initial orientation. Slip tendency analysis was also performed to infer the relative slip and dilation potentials of the observed structures. Mesoscopic analysis of preserved structures from the incipient and intermediate stages of development and evolution of the refracted FFP allowed us to build an evolutionary scheme wherein: a) Nucleation of refracted FFP occurs within weak layers; b) Refraction is primarily controlled by grain size and clay mineral content and variations thereof at layer-layer interfaces but also within individual layers; c) Propagation within strong layers occurs primarily by fluid-assisted development ahead of the FFP tip of a “process zone” defined by a network of hybrid and tensile fractures; d) The process zone causes the progressive weakening and fragmentation of the affected rock volume to eventually allow the FFP to propagate through the strong layers; e) Enhanced suitable conditions for the development of tensile and hybrid fractures can be also achieved thanks to the important role played by pressured fluids.

During the last decades, postglacial faults (PGFs) have been found in northern Fennoscandia, the first fault scarps being discovered in western Finnish Lapland in the 1960s. With LiDAR-based digital elevation models (DEMs), a new and accurate remote sensing mapping methodology has been acquired. It allows the relatively rapid and low-cost detection and mapping of late- or PGFs and, for instance, mapping of landslides from areas where they have not previously been recognized. We describe the approach of the Geological Survey of Finland to the systematic search for (screening) and mapping of PGFs, paleolandslides, and other morphological features of Quaternary deposits related to post- and late-glacial seismic activity in Finland. The observations have been collected and classified into a file geodatabase with ArcGis (© ESRI) using a procedure that includes several steps. We also provide examples from western and northern Finland of how sites of late- and postglacial fault scarps and landslides have...

We evaluated the performance of the Disease State Index (DSI) method when predicting progression to Alzheimer's disease (AD) in patients with subjective cognitive impairment (SCI), amnestic or non-amnestic mild cognitive impairment (aMCI, naMCI). The DSI model measures patients' similarity to diagnosed cases based on available data, such as cognitive tests, the APOE genotype, CSF biomarkers and MRI. We applied the DSI model to data from the DE-SCRIPA cohort, where non-demented patients (N=775) with different subtypes of cognitive impairment were followed for 1 to 5 years. Classification accuracies for the subgroups were calculated with the DSI using leave-one-out cross-validation. The DSI's classification accuracy in predicting progression to AD was 0.75 (AUC=0.83) in the total population, 0.70 (AUC=0.77) for aMCI and 0.71 (AUC=0.76) for naMCI. For a subset of approximately half of the patients with high or low DSI values, accuracy reached 0.86 (all), 0.78 (aMCI), and 0.85 (naMCI). For patients with MRI or CSF biomarker data available, they were 0.78 (all), 0.76 (aMCI) and 0.76 (naMCI), while for clear cases the accuracies rose to 0.90 (all), 0.83 (aMCI) and 0.91 (naMCI). The results show that the DSI model can distinguish between clear and ambiguous cases, assess the severity of the disease and also provide information on the effectiveness of different biomarkers. While a specific test or biomarker may confound analysis for an individual patient, combining several different types of tests and biomarkers could be able to reveal the trajectory of the disease and improve the prediction of AD progression.

International audience

The brittle deformation history of southwestern Finland was reconstructed through paleostress inversion of fault-slip data from outcrops and drill cores at the site of a planned nuclear waste repository. Seven distinct paleostress states have been resolved spanning 1.7Ga of geological history. (1) NW-SE to NNW-SSE transpression acted soon after 1.75Ga, when conditions leading to brittle deformation were first attained. (2) N-S to NE-SW transpression caused partial reactivation of (1). (3) NW-SE extension followed during the Gothian event and at the time of rapakivi magmatism. (4) Renewed NE-SW transtension occurred between 1.60 and 1.30Ga, forming the NW-SE-elongated Satakunta graben. (5) A significant and so far unrecognised phase of NE-SW compression has been found to postdate both rapakivi granites and 1.27Ga olivine diabase sills. (6) E-W transpression followed during the early stages of the Mesoproterozoic Sveconorwegian orogeny and predated (7) almost coaxial E-W extension of the late Sveconorwegian orogenic collapse. Our results prove that the shield's 'crust fragmentation' (i.e. generation of new fractures) was short lived in comparison to its 'jostling phase' (i.e. reactivation of old fractures). The shield thus reached structural maturity with respect to its saturation with brittle structures already in the late Mesoproterozoic. We predict that that future stress changes will most probably be accommodated by reactivation of the existing and inherited brittle structures rather than by formation of new deformation zones. © 2014 Elsevier Ltd.

Background: The diagnosis of Alzheimer's disease (AD) is based on an ever-increasing body of data and knowledge making it a complex task. The PredictAD tool integrates heterogeneous patient data using an interactive user interface to provide decision support. The aim of this project was to investigate the performance of the tool in distinguishing AD from non-AD dementia using a realistic clinical dataset. Methods: We retrieved clinical data from a group of patients diagnosed with AD (n = 72), vascular dementia (VaD, n = 30), frontotemporal dementia (FTD, n = 25) or dementia with Lewy bodies (DLB, n = 14) at the Copenhagen Memory Clinic at Rigshospitalet. Three classification methods were applied to the data in order to differentiate between AD and a group of non-AD dementias. The methods were the PredictAD tool's Disease State Index (DSI), the naïve Bayesian classifier and the random forest. Results: The DSI performed best for this realistic dataset with an accuracy of 76.6% compared to the accuracies for the naïve Bayesian classifier and random forest of 67.4 and 66.7%, respectively. Furthermore, the DSI differentiated between the four diagnostic groups with a p value of Conclusion: In this dataset, the DSI method used by the PredictAD tool showed a superior performance for the differentiation between patients with AD and those with other dementias. However, the methods need to be refined further in order to optimize the differential diagnosis between AD, FTD, VaD and DLB.

Sediment profiles in six lake basins located near the late- and postglacial fault surface ruptures in northern Finland were investigated for turbidites and soft-sediment deformation structures that could reveal information on the timing and spatial occurrence of paleoearthquakes in the area. We used geophysical sub-bottom profiling and lithological logging of sediment cores combined with radiocarbon and paleomagnetic dating. In three lakes, Immeljarvi, Aakenus and Laukkujarvi, sediment records provided evidence of postglacial earthquakes or landslides, whereas in three others (lakes Pyhajarvi, Kallojarvi and Syvajarvi) no disturbance structures were observed in their sequences that cover roughly the Holocene period. Combined with previous data on paleoseismicity in Finland, the results enhance the non-stationary hypothesis of seismicity throughout the Late Weichselian and the Holocene with three general maxima that cluster around the deglaciation (12.0–10.0 kyr BP), the mid-Holocene (5.0–7.0 kyr BP) and the Late Holocene (1.5–3.0 kyr BP). A strong asymmetry of the offset profiles of the Finnish postglacial fault complexes indicate that the general rupture propagation was from SW to NE. The present data also indicates that the oldest and highest magnitude events (MW ≈ 7 or higher) generally took place in the SW sector of the Finnish PGF complexes during or soon after the retreat of the continental ice sheet. The ruptures then propagated towards the NE sector of PGF complexes in a cascading fashion and were generally characterized by lower magnitude events (MW ≈ 6) during the Holocene.

Outdoor concrete structures such as concrete facade panels and balcony frame panels are subjected to various environmental actions causing reinforcement corrosion problems. Long-term field measurement data on reinforcement corrosion in carbonated concrete on these structures was utilized in the creation of a corrosion rate regression model combining weather parameters such as temperature, relative humidity, wind-driven rain and solar radiation to corrosion rate. A versatile model capable of predicting the effect of varying environmental actions on the corrosion rates of carbonation induced corrosion was produced. Wind-driven rain was found to have the greatest impact on corrosion rate in tandem with the micro climate surrounding the building. Due to changes in air temperature, air relative humidity as well as in the amount of wind-driven rain and solar radiation, the corrosion rate on concrete facades and balconies is constantly changing. Despite the high seasonal and yearly variation, the average level of the modelled corrosion rate was quite steady on a longer 30-year perspective. This information is substantial for the long term service life design of concrete structures.

Objectives: Optimal selection of idiopathic normal pressure hydrocephalus (iNPH) patients for shunt surgery is challenging. Disease State Index (DSI) is a statistical method that merges multimodal data to assist clinical decision-making. It has previously been shown to be useful in predicting progression in mild cognitive impairment and differentiating Alzheimer's disease (AD) and frontotemporal dementia. In this study, we use the DSI method to predict shunt surgery response for patients with iNPH. Methods: In this retrospective cohort study, a total of 284 patients (230 shunt responders and 54 non-responders) from the Kuopio NPH registry were analyzed with the DSI. Analysis included data from patients' memory disorder assessments, age, clinical symptoms, comorbidities, medications, frontal cortical biopsy, CT/MRI imaging (visual scoring of disproportion between Sylvian and suprasylvian subarachnoid spaces, atrophy of medial temporal lobe, superior medial subarachnoid spaces), APOE genotyping, CSF AD biomarkers, and intracranial pressure. Results: Our analysis showed that shunt responders cannot be differentiated from non-responders reliably even with the large dataset available (AUC?=?0.58). Conclusions: Prediction of the treatment response in iNPH is challenging even with our extensive dataset and refined analysis. Further research of biomarkers and indicators predicting shunt responsiveness is still needed.

Traumatic brain injury (TBI) is a major cause of death and disability, especially in young adults. A reliable prediction of outcome after TBI is of great importance in clinical practice and research. We aimed to compare performance of the well-established IMPACT calculator and an alternative method, Disease State Index (DSI), in the prediction of six-month outcome after TBI. Performance of the models was evaluated using 2036 patients with moderate or severe TBI from the International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) database. Prediction performance of both models was similar. The models with more variables provided better performance than the simpler models. This study showed that the DSI is a valid tool with efficient visualizations that can help clinicians with their decision making process in clinical practice.

Background: Disease State Index (DSI) and its visualization, Disease State Fingerprint (DSF), form a computer-assisted clinical decision making tool that combines patient data and compares them with cases with known outcomes. Aims: To investigate the ability of the DSI to diagnose frontotemporal dementia (FTD) and Alzheimer's disease (AD). Methods: The study cohort consisted of 38 patients with FTD, 57 with AD and 22 controls. Autopsy verification of FTD with TDP-43 positive pathology was available for 14 and AD pathology for 12 cases. We utilized data from neuropsychological tests, volumetric magnetic resonance imaging, single-photon emission tomography, cerebrospinal fluid biomarkers and the APOE genotype. The DSI classification results were calculated with a combination of leave-one-out cross-validation and bootstrapping. A DSF visualization of a FTD patient is presented as an example. Results: The DSI distinguishes controls from FTD (area under the receiver-operator curve, AUC = 0.99) and AD (AUC = 1.00) very well and achieves a good differential diagnosis between AD and FTD (AUC = 0.89). In subsamples of autopsy-confirmed cases (AUC = 0.97) and clinically diagnosed cases (AUC = 0.94), differential diagnosis of AD and FTD performs very well. Conclusions: DSI is a promising computer-assisted biomarker approach for aiding in the diagnostic process of dementing diseases. Here, DSI separates controls from dementia and differentiates between AD and FTD.

The relationship between present-day stress state and fluid flow within fractures in crystalline bedrock is investigated in the light of a comprehensive fracture database consisting of 38,703 fracture observations made during investigations at the site of a planned high-level nuclear waste repository in Finland. By combining fracture orientation data with detailed stress and fluid flow measurements, we observe that the orientations of conductive fractures display characteristic patterns attributed to the effect of the present-day triaxial stress state and that the highest transmissivities are associated with fractures having the lowest normal tractions. Our findings indicate that contemporary stress data combined with slip and dilation tendency analysis can be used in predicting the orientations and relative transmissivity values of conductive fractures.