In the mid-sixties of the 20th century, a seismicity one-dimensional model, based on a spring system with friction, was presented by the two authors mentioned in the title. Through this model was studied the viscosity behaviour involved in the stratums mutual displacement. However, in the analysis pertinent to the occasion, seeing the fig.13 ibid it can be observed an error related to the viscosity function (low speeds’) limits, which determines its “performance” during the time - lapse of the stratums breaking. From the height of the present knowledge, using the Elementary Catastrophes Theory developed in later times by René Thom and Zeeman, we have reached certain conclusions which, although do not refute the results of said article, they can significantly improve some aspects of the model and in general of the earthquakes physics.

Anhydrous carbonate shortite compressed in the aqueous fluid at high P-T (up to 5 GPa, 350°C) was studied with in situ Raman spectroscopy. The DFT was used to calculate the lattice dynamics and interpret the vibrational spectra. The shortite Raman bands are broadening with pressure and temperature, and signal are decreasing that is caused by gradual structure amorphisation accompanied by an orientational disordering of CO$_3$ triangle units. Despite the aqueous medium presence at high temperature and pressure, shortite did not go hydrated. At 3.2 GPa and 250°C, shortite begins to dissolve followed by crystallisation of aragonite and aragonite’ . A remnant part of shortite crystals was presented in the ex-situ sample. The transition of shortite to aragonite’ was monitored by in situ Raman spectra in the C-O stretching range: strong doublet transforms into singlet at ~4 GPa, 250°C. Additionally, the phases X-phase is characterised by strongest narrow 1358 cm-1 band. X1- and X2-phases are expected to represent organic materials are the most believable Na-formate and some polymorphs of Ca-formate. The unusual behaviour of aqueous carbonate fluid was observed at 4.8 GPa and 300-350°C. This process is characterised by the active formation of micro-bubbles that are inserted one into another. The existence time of the micro-bubbles is varied within 2-60 seconds. Micro-bubbles are considered to be a result of the two immiscible fluids stratification. This unusual dynamical immiscibility of the fluid promotes the appearance of several crystalline carbonates and organic molecular crystals.

The isotopic composition of paleosol carbonates are used extensively to reconstruct past vegetation, climate, and altimetry, but poor constraints on soil evaporation and temperature have limited the utility of oxygen isotopes in the studies. Recent advances in carbonate clumped isotope thermometry (T∆47) allow for independent controls on temperature, but the influence of evaporation remains unresolved. However, the sensitivity of 18O-17O-16O distributions to kinetic fractionation makes it possible to use triple oxygen isotopes (∆ʹ17O) to track evaporation in water. Recent work shows the sensitivity of ∆ʹ17O to evaporation in lakes and lacustrine carbonates, but little is known about variation of ∆ʹ17O in soil carbonates and their potential to track evaporation. For this study, we sampled soils across an aridity gradient in the Serengeti, Tanzania to evaluate how soil carbonate ∆ʹ17O tracks soil water evaporation. Modern soil carbonates were collected from 11 sites across a transect of the Serengeti Ecosystem where mean annual precipitation and aridity index range from 499 to 846 mm yr 1 and 0.33 to 0.55, respectively. δ13C values range from -2.7 to 1.8‰ and reflect C4 dominated grasslands, whereas δ18O values of soil carbonates vary by ~8‰ along a gradient in aridity. T∆47 from these soil carbonates average 23°C (1σ ±4°C), which does not vary significantly across sites or with depth, likely due to minimal annual variation in temperature at the equator. Using these temperatures for each carbonate, reconstructed δ18O values of soil water are up to 6‰ higher than δ18O values of local precipitation and springs, indicating considerable soil water evaporation. The ∆ʹ17O values of these soil carbonates range from -162 to -106 per meg and decrease as both aridity and δ18O values increase. Our results support the hypothesis that soil water evaporation drives the variance in δ18O and ∆ʹ17O of soil carbonate in arid climates, demonstrating the potential for soil carbonate ∆ʹ17O to track paleoaridity and constrain interpretations of paleosol carbonate δ18O records.

Over the past decade, the huge success in many large-scale projects like the USArray component of Earthscope gave rise to a massive increase in the data volume available to the seismology community. We assert that the software infrastructure of the field has not kept up with parallel developments in ‘big data’ sciences. As a step towards enabling research at the extreme scale to more of the seismology community, we are developing a new framework for seismic data processing and management we call Massive Parallel Analysis System for Seismologists (MsPASS). MsPASS leverages several existing technologies: (1) Spark as the scalable parallel processing framework, (2) MongoDB as the flexible database system, and (3) Docker and Singularity as the containerized virtual environment. The core of the system builds on a rewrite of the SEISPP package to implement wrappers around the widely accepted ObsPy toolkit. The wrappers automate many database operations and provide a mechanism to automatically save the processing history and provide a mechanism for reproducibility. The synthesis of these components can provide flexibility to adapt to a wide range of data processing workflows. The use of containers enables the deployment to a wide range of computing platforms without requiring intervention by system administrators. We evaluate the effectiveness of the system with a deconvolution processing workflow applied to USArray data. Through extensive documentation and examples, we aim to make this system a sustainable, open-source framework for the community.

Soils of mountain regions are estimated to contain large amounts of organic matter (OM), equivalent to stocks found in high-latitude boreal and tundra soils. Mountain environments are also experiencing profound changes in land management under the influence of socio-economic pressures as well as the need to adapt to climate change, which is occurring at a faster rate than in lowland areas. These anthropogenic impacts are expected to strongly affect soil OM storage. Most studies of land-use change have however focused on topsoil OM; whether similar trends will hold true for subsoil OM remains unknown. Using Rock-Eval pyrolysis as a proxy for soil OM dynamics, we showed that the hierarchy of controls on OM properties and transformations varied greatly with increasing soil depth. In the topsoil, OM properties were related to the nature of plant inputs, their degree of in-mixing with the mineral matrix and the occurrence of seasonal water saturation. In the subsoil however, the foremost predictors of OM properties were geochemical parameters. This shift in the nature of determinants of OM dynamics indicates that shallow and deep soil OM pools should respond differently to external forcings. Podzolic profiles showed the strongest decoupling of topsoil and subsoil OM properties. We focused on this soil type to specifically investigate the effects of land use on subsoil OM. We selected field sites from the Coastal Range of British Columbia, Canada and the Pennine Alps, Switzerland representing undisturbed and managed forest, shrubland and pasture. Samples were analyzed for organic C content, OM quality and reactive mineralogy. Results showed that herbaceous cover was associated with an increase in topsoil but not subsoil OM. In the subsoil, variations in OM content and properties were associated with changes in reactive Al and Fe mineral phases. Overall, our data indicate that organo-mineral and organo-metal interactions are of prime importance to OM accumulation in the subsoil, and that understanding the response of deep soil C stocks to land use change will require consideration of the geochemical and mineralogical environment. Our results further suggest that so-called reactive mineral phases may themselves be impacted by land use, in turn affecting deep soil C stabilization and destabilization processes.

Seismological models of the mantle are routinely developed using a range of techniques applied to different data types. For quite some time, it has been recognised that on long wavelengths models of shear-wave velocity variations show a large degree of consistency. More recently, the same has been suggested for models that describe compressional-wave velocity variations. However, controversy remains regarding models of lower mantle density variations, which provide important constraints on the nature of mantle structures, e.g. whether they are caused by thermal variations or whether additional chemical heterogeneity is required. The imaging of density structure is difficult due to a small effect on seismic observables and a strong trade-off with core-mantle boundary (CMB) topography. In addition, no consistent model of CMB topography variations exists with current models differing both in amplitude and pattern. Here, I review models of lower mantle density structure and core-mantle boundary topography from the literature, with the aim to identify which structures are consistent and what we can already learn from these models. In addition, I discuss ways in which differences between existing models may be resolved in future.

Water ice clouds form in the mesospheres of terrestrial planets in the solar system (and most likely elsewhere) by vapor deposition at low pressures and temperatures. Under these conditions a range of crystalline and amorphous phases of ice might form. The phase is important because it influences nucleation kinetics, density, vapor pressure over the solid, growth rates and particle shape. In the past the temperature range over which these different phases exist has been defined on the basis of depositing ice at low temperature and warming it while observing phase changes. However, the direct deposition of ice at a range of temperatures relevant for the terrestrial planets has not been systematically investigated. Here we present X-ray Diffraction (XRD) measurements of water ice deposited at temperature intervals between 88 and 145 K in a vacuum chamber. XRD patterns showed that low density amorphous ice was formed at ≤ 120 K, stacking disordered ice I formed from 121 – 135 K and hexagonal ice I formed at 140 and 145 K. Direct deposition results in the stable hexagonal phase at much lower temperatures than when warming stacking disordered ice. All three phases of water ice observed here are possible in clouds in the mesospheres of Earth and Mars, while on Venus only amorphous ice is likely to form.

Useful to Usable (U2U) was a 6-year USDA-funded research and extension project focused on improving the uptake of climate information by Midwestern U.S. farmers and agricultural advisors. Led by Purdue University, this interdisciplinary team from nine Midwestern universities developed five web-based decision support tools to examine production, financial, and environmental outcomes of different climate scenarios and management options. A dedicated team of Extension educators, marketing specialists, and program evaluators worked together to promote U2U products and collect, analyze, and communicate data to 1) help increase project impact and 2) to measure outcomes for accountability purposes. Since outreach began in July 2013, farmers and advisors have been reached at 165 outreach events and training sessions in ten Midwestern states and at least 6 regional webinars have been conducted. A four-round mailed and electronic marketing campaign reached an estimated 35,600 people from March 2015 – November 2016. Additionally, the team developed a variety of educational materials (user guides, fact sheets, presentations, etc.) to support U2U outreach and dissemination efforts. Throughout 2016-2017, the team evaluated the outcomes, impacts, and overall reach of the U2U project over the 6-year project duration. They conducted two large-scale surveys with farmers and agricultural advisors, conducted personal interviews with advisors in Iowa and Nebraska, gathered informal success stories from U2U team members and collaborators, and tracked website traffic using Google Analytics. This presentation will highlight the project’s evaluation design, results, and lessons learned, including evaluation of outreach and dissemination approaches and longer-term outcome/impact evaluation. Some key metrics include the likelihood of using U2U online tools, actual use of tools, use of tools to aid financial and environmental decisions, and willingness to consider climate information in the future (not limited to U2U tools).

Terrestrial-aquatic interfaces such as salt marshes, mangroves, and similar wetlands provide an optimum natural environment for the sequestration and long-term storage of carbon (C) from the atmosphere, commonly known as coastal blue carbon. There are over 4 million acres of salt marsh in the US and over half of these are along the east coast of the US. Due to anthropogenic activities, this area presents the greatest nitrogen (N) pollution problem in coastal ecosystems in the U.S. as part of atmospheric N deposition, runoff, and riverine export. Ammonia (NH3) is the most abundant alkaline gas in the atmosphere. Agricultural intensification is the primary anthropogenic source of NH3 leading to a doubling of reactive nitrogen (Nr) entering the biosphere. Despite this, there are limited atmospheric measurements of NH3 concentrations in coastal areas along the east coast. The objective of this study is to advance our process-level understanding of NH3 air-surface exchange over a tidal salt marsh at the Saint Jones Reserve (DE), which is part of the National Estuarine Research Reserve System (NERRs). Continuous and high temporal resolution measurements of atmospheric NH3 concentrations were measured using a cavity ring-down spectrometer, reporting 30 min concentration averages. These high temporal resolution measurements allowed the estimation of the average diurnal cycle of NH3 fluxes using a new analytical methodology. Micrometeorological measurements were also measured using the eddy covariance system operated concurrently above the tidal marsh at the research site, which is part of the AmeriFlux network (US-StJ). This pilot study represents one of the few atmospheric measurements of NH3 over a tidal salt marsh in the eastern U.S. Such measurements are important to characterize the processes that influence the exchanges of NH3 between the atmosphere and the aquatic surface and provide baseline data to form more reliable parameterizations to simulate NH3 deposition and emissions in tidal salt marshes using surface-atmosphere transfer models.

While flagship missions such as CHAMP and GOCE have shown us with accelerometer measurements that the thermospheric density in Low Earth Orbit (LEO) can increase by more than 200% during enhanced geomagnetic activity, current empirical models, such as those of the MSISE and Jacchia families, as well as the Drag Temperature Model, fail to reproduce this behavior, limiting the ability to perform orbit prediction and space situational awareness. Several methods have been employed to address this dilemma. One is the High-Accuracy Satellite Drag Model (HASDM), which uses its Dynamic Calibration Atmosphere to employ differential correction across 75 spherical calibration satellites to generate correction parameters to the density that are related to 10.7 cm solar radio flux and ap (Storz et al. 2005). Doornbos et al. 2008 has implemented a method that estimates height-dependent scale factors to the densities from empirical models with respect to densities directly derived from two- line element sets (TLEs). HASDM’s reliance on Space Surveillance Network observations limit its accessibility and detail, and Doornbos’ methods are limited by the fact that TLEs are mean elements; densities derived from them are subject to errors due to smoothing over an entire orbit. In addition, the method of deriving densities from TLEs was initially done only to provide inputs to the SGP4 orbital propagator, which was initially developed without consideration of solar radiation pressure on the trajectory of modeled spacecraft. We present a method to generate new model densities during geomagnetic storms by using an in-house orbital propagator, the Spacecraft Orbital Characterization Kit (SpOCK). This method estimates and applies scale factors to F10.7 and a p to minimize orbit propagation errors with TLEs. The method is tested on a variety of satellites, including CHAMP, GOCE, and the CubeSats of the QB50 and FLOCK constellations. This method proposes to grant insight into storm-time thermospheric density enhancement by modeling the effects of storms on the drag of numerous LEO spacecraft, increasing our understanding of thermospheric dynamics and granting us improved tools for space traffic management and thermospheric research.

This study discusses the role of the aridity index in controlling the long-term fluxes of direct (Qd) and baseflow (Qd). Here we present an analytical derivation starting from similar assumptions as the one presented in the original work of Budyko that leads to two simple expressions for the control of the aridity index on Qb and Qd. These two analytical equations can be combined into a single expression with the same properties as the original Budyko equation. Our study provides a method for predicting long term baseflow and direct runoff for poorly gaged basins as well as permit the derivation of sensitivity equations for the assessment of the impact of these fluxes with respect to changes in aridity index.

Forest biodiversity has been declining across the globe due to anthropogenic activities. Losses of biodiversity have led to reduced forest health and ecosystem services. Therefore, it has become necessary to monitor changes in biodiversity over wide geographic areas. Remote sensing has the potential to monitor biodiversity changes, but the accuracy in which it can be estimated is under debate. In this study, we tested 1) the relationship among distinct metrics of biodiversity, 2) the role topographic measures have on determining biodiversity, and 3) the ability of hyperspectral remote sensing to estimate biodiversity in temperate forests of the Northeastern United States. We characterized biodiversity according to four different metrics: species, functional, structural, and phylogenetic diversity. All four metrics were quantified using species inventory data as well as Light Detecting and Ranging (LiDAR) to calculate additional indices of structural diversity. A digital elevation model was used to obtain measures of slope, aspect, and other topographic indices such as topographic wetness. Hyperspectral imagery was used to obtain reflectance, entropy, and several vegetation indices. In our analyses, species, functional, and phylogenetic diversity were shown to be moderately correlated suggesting similarities between the metrics while correlations between structural diversity and the other metrics were weak. The calculated topographic indices also showed weak correlations with the biodiversity metrics suggesting that topography does not influence measures of biodiversity at the plot level. Depending on the biodiversity metric, relationships between the hyperspectral analyses and biodiversity were weak to moderately strong. These findings suggest that hyperspectral imagery holds some potential for estimating multiple metrics of biodiversity.

Many human activities rely on accurate knowledge of the sea surface dynamics. This is especially true during storm events, when wave-current interactions might represent a leading order process of the upper ocean. In this study, we assess and analyse the impact of including three wave-dependent processes in the ocean momentum equation of the Met Office North West European Shelf (NWS) ocean-wave forecasting system on the accuracy of the simulated surface circulation. The analysis is conducted using ocean currents and Stokes drift data produced by different implementations of the coupled forecasting systems to simulate the trajectories of surface (iSphere) and 15 m drogued (SVP) drifters affected by four storms selected from winter 2016. Ocean and wave simulations differ only in the degree of coupling and the skills of the Lagrangian simulations are evaluated by comparing model results against the observed drifter tracks. Results show that, during extreme events, ocean-wave coupling improves the accuracy of the surface dynamics by 4%. Improvements are larger for ocean currents on the shelf (8%) than in the open ocean (4%): this is thought to be due to the synergy between strong tidal currents and more mature decaying waves. We found that the Coriolis-Stokes forcing is the dominant wave-current interaction for both type of drifters; for iSpheres the secondary wave effect is the wave-modulated water-side stress while for SVPs the wave-dependent sea surface roughness is more important. Our results indicate that coupled ocean-wave systems may play a key role for improving the accuracy of particle transport simulations.

Stochastic physics (SP) schemes provide a more realistic representation of the unresolved scales in global circulation models by improving both mean climate and climate variability. We study the impact of including an SP scheme in the atmospheric component of EC-Earth on the simulated climate. In particular, we analyze the evolution of the sea-ice extent in the Arctic during long-term simulations covering the historical and future periods. The experiments consist of coupled climate simulations in which three ensemble members constitute the control runs (base) and three ensemble members include stochastic physics (stoc). For the latter, the Stochastically Perturbed Parametrization Tendencies (SPPT) scheme is incorporated in the atmospheric component of EC-Earth. The original experiments, that are part of the SPHINX project, span from 1850 to 2100. We have additionally extended each simulation for 60 years; the future scenario corresponds to the CMIP5 RCP8.5 set up. We compare both sets of experiments to investigate the climate response to a perturbed atmosphere. The simulated Arctic sea-ice extent in September and March display an overall decrease. The sea-ice loss results faster in the base experiments than in the stoc ones. The model simulates an abrupt sea-ice loss in March that takes place about 10 years earlier in the base experiments than in the stoc ones. The evolution of the global annual mean surface air temperature differs if the SP is on or off. Curves start separating by the second half of the 20th century; reach the maximum difference in 2100 and become almost indistinguishable around 2110. Our results suggest that the transient climate sensitivity is lower when the SP is on than when it is off during the 21st century. However, the opposite occurs when the Arctic is free of sea ice along the whole year. This behavior might be the consequence of the asymmetric effect of stochastic perturbations on the process of condensation. We are now investigating the differences in the albedo and cloud feedbacks between both sets of experiments and the possible influence of the mean state on the model climate sensitivity.

Microbial processing of fresh carbon inputs is recognized as a key step in the formation of mineral-associated organic matter. Low molecular weight (LMW) compounds comprise a notable fraction of these inputs and are rapidly assimilated and metabolized by the microbial community. In this work, we employ ecophysiological studies of microbial isolates to better understand the role of substrate identity as a control on preferences, uptake kinetics, and carbon use efficiencies (CUE) across a gradient of phylogenetic differences (gram negative, gram positive, and fungal). Soil-extracted, solubilized organic matter (SESOM) derived from the Oa horizon of a hemlock-hardwood forest stand and synthetic media based off of this extract were chosen as liquid media for batch growth studies. A combination of exometabolomic techniques (1H NMR, UHPLC-MS) were used to quantify 35 LMW substrates in the original extract (0.4 – 195 μM), comprising 19.5% of total C and 39.9% of total N. Consumption of these substrates by microbial isolates accounted for a substantial amount of total C and N assimilated during growth, representing 43-75% and 58-74%, respectively. Time resolved sampling allowed modeling of sigmoidal uptake curves and the comparison of the midpoint of consumption (Th, hr) and 90% usage windows (ranging from 0.18 – 2.29 hr). Complementary experiments were conducted using synthetic media with all substrates at equimolar concentrations (25 μM) to better constrain the impact of initial concentration. We use stable isotope probing to determine CUE for five different LMW substrates of interest (glucose, acetate, formate, glycine, and valine). Ultimately, we are interested in whether unifying trends can be observed across the physiological gradient and how the metabolic transformations of these inputs may impact the organo-mineral formation process.

Observations of fold growth in fold-thrust belt settings show that brittle deformation can be localized or distributed. Localized shear is associated with frictional slip on primary faults, while distributed brittle deformation is recognized in the folding of the bulk medium. The interplay of these processes is clearly seen in fault-bend folds, which are folds cored by a fault with an abrupt change in dip (e.g., a ramp-décollement system). While the kinematics of fault-bend folding were described decades ago, the dynamics of these structures remain poorly understood, especially the evolution of fault slip and off-fault deformation over different periods of the earthquake cycle. In order to investigate the dynamics of fault-bend folding, we develop a numerical modeling framework that combines a long-term elasto-plastic model of folding in a layered medium with a rate-state frictional model of fault strength evolution in order to simulate geologically and mechanically consistent earthquake sequences. In our simulations, slip on the ramp-décollement fault and inelastic fold deformation are mechanically coupled processes that build geologic structure. As a result, we observe that folding of the crust does not occur steadily in time but is modulated by earthquake cycle stresses. We suggest combining seismological and geodetic observations with geological fault models to uncover how elastic and inelastic crustal deformation generate fault-bend folds. We find that distinguishing between the elastic and inelastic response of the crust to fault slip is possible only in the postseismic period following large earthquakes, indicating that for most fault systems this information currently remains inaccessible.

Agriculture sector is a major consumer of available fresh water. Increasing demand for fresh water in the various sectors has necessitated the use of treated waste water for irrigation. This water has marginal amount of salts which are known to affect the soil properties and crop growth. Hence a scientific approach is necessary to model the moisture uptake by plant roots under varying saline conditions. A numerical model is developed for solving the one dimensional Richards equation for moisture movement in variably saturated vadose zone. The root water uptake is incorporated in the model as the sink term as per the Ojha and Rai (1996) model, which is a non-linear root water uptake model. Combined water and salinity stress in the root water uptake is incorporated as per Feddes et al. (1978) and Mass and Hoffman (1977). Effect of varying salinity concentrations on the water uptake by plant roots and soil moisture dynamics in the root zone is studied on a 40 day period of crop growth. This is attained by providing fresh water and saline water irrigation with 15, 30 and 50 dS/m electrical conductivity. Irrigation field experiments of winter wheat crop were carried out to measure the crop parameters used in the analysis like leaf area index and root depth. The analysis to study the effect of salinity on soil water retention (SWR), hydraulic parameters and plant root water uptake was performed for silt loam (fine textured) and sandy loam (coarse textured) soils. The results show that the roots extract water at potential rate with fresh water, with no water uptake in the case of higher salinity as osmotic stress reaches permanent wilting phase. Overall, the root water uptake reduces as the concentration of salinity increases, even if there is no water stress. However, water stress was encountered at an earlier time in the case of sandy loam soil than in the case of silt loam. As the water content falls below the available moisture content, the water uptake is affected by water stress, which affects the growth and yield of crops. The results obtained from the study are useful in the better management of available water resources for irrigation practices in crop production.

Strong strain and pore pressure changes are observed after three Mw 4.5+ local and one Mw 7.2 regional earthquakes during 2010‒2017 in borehole strainmeters near Anza, California. The strain change emerges immediately after the earthquakes and lasts 40‒100 days with amplitudes up to 1e−7, larger than the coseismic strain offsets. The pore pressure exhibits change immediately after the earthquakes at some boreholes and with a delay of 4‒10 days at the others. A joint analysis of the observed postseismic strain and pore pressure change suggests that the postseismic strains could be explained by combined effects of poroelastic deformation due to earthquake-induced pore pressure change and elastic deformation due to an earthquake-triggered aseismic slip on a nearby fault. Our study indicates that, in addition to possible aseismic fault slips triggered by an earthquake, pore pressure changes after the earthquake could be even more important in producing postseismic deformation.