Decoupled kinematics of two neighbouring permafrost creeping landforms in the Eastern Italian Alps

An overall acceleration of rock glacier displacement rates in the Alps has been observed in recent decades, with several cases of destabilization leading to potential geomorphological hazards. This behaviour has been attributed to the rising permafrost temperature, induced by atmospheric warming and regulated by thermo-hydrological processes. Landforms derived from the interaction of glacier remnants and permafrost are widespread in mountain areas, but are less studied and monitored than talus rock glaciers. This work presents a comparative study of a talus rock glacier and a glacial-permafrost composite landform (GPCL) in the Eastern Italian Alps. The two landforms are only 10 km apart, but have rather different elevation ranges and main slope aspects. The kinematics and ground thermal conditions were monitored from 2001 to 2015 along with geomorphological surveys, analyses of historical maps and remote sensing data. The dynamic behaviour of the rock glacier was similar to the majority of monitored rock glaciers in the Alps, with an acceleration after 2008 and a velocity peak in 2015. In contrast, the GPCL had a nearly unchanged displacement rate during the observation period. Statistical analyses of kinematic vs. nivo-meteorological variables revealed a dynamic decoupling of the two landforms after 2008 that corresponds with increased winter snow accumulation. Although the kinematics of both landforms respond to ground surface temperature variations, the collected evidence suggests a different reaction of ground surface temperature to variations in the precipitation regime. This different reaction is likely due to local topo-climatic conditions that affect snow redistribution by wind. The different reactions of the two systems to the same climatic forcing is likely a legacy of their different origins. GPCL dynamics result from interaction of permafrost and residual glacial dynamics that are associated with possible peculiarities in the internal/basal meltwater circulation, whose future response is uncertain and requires improved understanding. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.     

Modern diatom, cladocera, chironomid, and chrysophyte cyst assemblages as quantitative indicators for the reconstruction of past environmental conditions in the Alps. I. Climate

Diatom, chrysophyte cyst, benthic cladocera, planktonic cladocera, and chironomid assemblages were studied in the surface sediments of 68 small lakes along an altitudinal gradient from 300 to 2350 m in Switzerland. In addition, 43 environmental variables relating to the physical limnology, geography, catchment characteristics, climate, and water chemistry were recorded or measured for each lake. The explanatory power of each of these predictor variables for the different biological data-sets was estimated by a series of canonical correspondence analyses (CCA) and the statistical significance of each model was assessed by Monte Carlo permutation tests. A minimal set of environmental variables was found for each biological data-set by a forward-selection procedure within CCA. The unique, independent explanatory power of each set of environmental variables was estimated by a series of CCAs and partial CCAs. Inference models or transfer functions for mean summer (June, July, August) air temperature were developed for each biological data-set using weighted-averaging partial least squares or partial least squares. The final transfer functions, after data screening, have root mean squared errors of prediction, as assessed by leave-one-out cross-validation, of 1.37 °C (chironomids), 1.60 °C (benthic cladocera), 1.62 °C (diatoms), 1.77 °C (planktonic cladocera), and 2.23 °C (chrysophyte cysts).     

Experimental exsolution textures in the system bornite-chalcopyrite: Genetic implications concerning natural ores

Textural interpretation of ore-mineral assemblages, such as bornite-chalcopyrite (bn-cpy) intergrowths, should be based on definite experimentation. Appropriate exsolution and coarsening experiments were performed using sealed, evacuated, silicaglass tubes; synthetic bn-cpy solid solutions were annealed between 100° and 350°C for times of 20 min to 10 weeks. Early-formed textures develop through nucleation and growth and depend on the initial degree of supersaturation and the metal diffusivities. Final textures, due to additional growth and coarsening, are very sensitive to temperature and may serve as geothermometers. Mutual boundary textures which form above 250°C can originate by: (1) simultaneous precipitation; (2) exsolution during slow cooling from above the solvus; and (3) metamorphism to temperatures above about 250°C. Widmanstätten textures are not compatible with slow cooling, but indicate: (1) low-temperature replacement of bn; or (2) exsolution of cpy lamellae from anomalous bn heated to around 200°–250°C during mild metamorphism.     

New results on standard solar models

We describe the current status of solar modeling and focus on the problems originating with the introduction of solar abundance determinations with low CNO abundance values. We use models computed with solar abundance compilations obtained during the last decade, including the newest published abundances by Asplund and collaborators. The results presented here focus on both helioseismic properties and models as well as neutrino flux predictions. We also discuss changes in radiative opacities to restore agreement between helioseismology, solar models, and solar abundances and show the effect of such modifications on solar neutrino fluxes.     

PRESTo,the earthquake early warning system for Southern Italy: Concepts,capabilities and future perspectives

PRESTo (PRobabilistic and Evolutionary early warning SysTem) is a software platform for regional earthquake early warning that integrates recently developed algorithms for real-time earthquake location and magnitude estimation into a highly configurable and easily portable package. The system is under active experimentation in Southern Italy on the Irpinia Seismic Network (ISNet), which is deployed in a seismogenic area that is expected to produce a large earthquake within the next 20 years. In this paper we describe the architecture of the system and test its performances using both small earthquakes (M<3.5) recorded at the ISNet and a large event recorded in Japan, through a simulation mode. The results show that, when a dense seismic network is deployed in the fault area, PRESTo can produce reliable estimates of earthquake location and size within 5–6 s from the event origin. Each estimate is provided as a probability density function, with an uncertainty that typically decreases with time: a stable solution is generally reached within 10 s from the origin.     

Earthquake early warning: Concepts,methods and physical grounds

Modern technology allows real-time seismic monitoring facilities to evolve into earthquake early warning (EEW) systems, capable of reducing deaths, injuries, and economic losses, as well as of speeding up rescue response and damage recovery. The objective of an EEW system is to estimate in a fast and reliable way the earthquake’s damage potential, before the strong shaking hits a given target.     

Dynamic active earth pressure on cantilever retaining walls

In normal practice, the active earth pressure on cantilever retaining wall is evaluated with different procedures relating to an ideal vertical plane passing through the heel of the wall. If the wall presents a long heel, failure planes do not interfere with the vertical stem, so that the limit Rankine conditions can develop freely in the backfill. The inclination of lateral actions along the ideal plane is assumed to be constant and depends on the geometry of the ground level and on the friction angle φ. The Authors recently proposed a new method to evaluate the active earth pressure coefficient due to seismic loading with a pseudo-static stress plasticity solution. The present paper describes the application of this method to a retaining wall supporting a φ soil backfill with an irregular surface. For two different configurations of wall-soil system, the behaviour is also studied by continuum FDM dynamic analyses, utilising four Italian accelerometric time-histories scaled at the same peak ground acceleration. The comparison between different procedures is also analysed.     

Succession and seasonal onset of colonization in subtidal hard‐bottom communities off northern Chile

Although there is extensive information concerning the colonization sequences of benthic communities, little is known about the successional development of subtidal hard‐bottom habitats in highly productive coastal upwelling areas. In these systems, succession is predicted to be fast due to high growth rate of the later dominant colonizers. Using artificial hard substrata a field experiment was conducted in a rocky subtidal area off Northern Chile (Humboldt Current System) and monitored at 3‐month intervals to test the following hypotheses: (i) epibenthic succession may proceed through consecutive replacement of species, (ii) there is a fast convergence rate towards natural communities, and (iii) different seasonal starting points for the colonization will produce different community structure over a 1‐year period of exposure. Panels were installed on a vertical wall at 17 m water depth. Three replicate panels were sampled every 3 months over a period of 27 months. As a reference, six haphazardly selected plots from the surrounding natural community were surveyed at each sampling date. To evaluate how seasonally varying substratum availability affects community development, further panels were exposed for a 12‐month period, starting in four different seasons (n = 3 replicates per season). Community succession was slow and occurred through progressive changes, between early encrusting red corallines, middle Balanus flosculus and late Lagenicella variabilis. After 27 months, the community composition, but not its structure, was similar between experimental and reference communities on surrounding rocky bottoms. Seasonality had no effects and after 1 year of exposure the experimental communities converged towards a common structure. This study indicates that succession of subtidal epibenthic communities follows a slow and predictable pattern with a dominant late colonial species. In addition, aseasonal variability might be more relevant during colonization and succession in this upwelling ecosystem.     

An experiment-based assessment of the feasibility of the CO2 geological storage in unexploited coal beds in northern Spain

The storage of CO₂ in unused coal mines is a viable option for reducing emissions of CO₂, whose accumulation in the atmosphere is one of the main contributors to global warming. Understanding CO₂ behaviour and storage capacity of the coal is an important first step before injecting the CO₂. We used experimental equipment to extract coal from a mine and to obtain a representative sample of both its internal structure (in terms of cleats, macropores, mesopores and micropores) and occluded gases. Storage capacity was studied in terms of variations in gas pressure. The adsorption isotherm was experimentally obtained applying a procedure specifically designed to avoid altering the coal. An unused coal bed was selected to determine how much CO₂ it could adsorb and to study the feasibility of storing power plant CO₂ in this kind of mine.