Miracle-dz/UniFAR-FTUs huggingface dataset:
Low‐Frequency Seismicity at Villarrica Volcano: Source Location and Seismic Velocities

Villarrica Volcano (Chile) is one of the most active volcanoes in South America. Its low‐frequency (≤5 Hz) seismicity consists of a continuous tremor, overlain by impulsive transient events of higher amplitude in 60‐s intervals. This signal was recorded in March 2012 by an extensive local network, comprising 75 stations and including 6 subarrays. It allowed us to apply and compare three techniques to locate the origin of the seismicity: intersection of propagation directions determined by array analysis, mapping amplitudes, and modeling of amplitude decay. All methods yield almost identical, temporally stable, epicenters inside the summit crater, which confirms earlier attributions of the seismicity to volcanic activity inside the conduit. The discrete transients and the interevent tremor share the same source location. From the dominance of surface waves and the obvious scattering, we infer a source near the surface. For two arrays at the northern and western flank, a dispersion relation was derived, which allowed for the determination of S wave velocity‐depth functions. At both locations, the velocity structure can be modeled by three layers with interfaces at 100 and 400m depths. The velocities (300 to 3,000 m/s) correspond to pyroclastic material at different states of consolidation. The modeling of the amplitude decay reveals a quality factor around 50.
An Anatomy of External Shocks in the Andean Region

This paper applies an agnostic structural vector autoregression (SVAR) approach to study the response of four Andean economies (Bolivia, Colombia, Ecuador, and Peru) to international shocks. More specifically, we look at the response of gross domestic product, the real exchange rate, fiscal and trade balances, and inflation to global demand, commodity price, monetary and financial shocks. Our results confirm that the Andean region is highly exposed to changes in external conditions, and especially to global demand fluctuations associated with declines in commodity prices. However, despite the similarities that characterize these countries in terms of their income level or their export specialization, we find substantial heterogeneity in the effects of the shocks, which we attribute to differences in the shock-absorbing capacity of their macroeconomic frameworks. This result underlies the need to put in place external buffers to fully exploit the benefits of a greater presence in international markets, be it in the form of exchange rate flexibility, international reserves, or fiscal and monetary space to act countercyclically.
Evidence for discrete star formation events in the Small Magellanic Cloud based on 6.5m Magellan Telescope observations

Abstract The Small Magellanic Cloud (SMC) presents us with a unique opportunity to study in detail the effect of environmental processes (interaction with the LMC and the Milky Way) on its star formation history. With the 6.5m Magellan Telescope at the Las Campanas Observatory in Chile we have acquired deep B and I images in four 0.44 degree fields covering a large part of the main body of the SMC, yielding accurate photometry for 1,068,893 stars down to ~24th magnitude, with a spatial resolution of 0.201 arcsec/pixel. Colour-magnitude diagrams and luminosity functions (corrected for completeness) have been constructed, yielding significant new results that indicate at least two discrete star formation events around 2.7 and 4-5 Gyr ago.
Measuring peatland carbon uptake by remote sensing

Peatlands are an important ecosystem for carbon storage, due to their semi-permanent water saturated condition which inhibits decomposition. Many peatlands in the UK have been degraded through human land use to the point where they are releasing carbon, and restoration is now a priority to protect these landscapes and the carbon held within them. Most methods of monitoring peatland restoration are small-scale and expensive. Remote sensing methods, however, are large-scale and often freely available to the end user. This project considers the potential benefits of using remote sensing to estimate peatland carbon uptake, and describes experiments which answer research questions in this area. Much of the work was done within the Forsinard Flows RSPB reserve, which has a chronosequence of blanket bog sites at different stages of restoration. A laboratory experiment on the effects of drought stress on the carbon flux and spectral reflectance of Sphagnum moss was first completed. This was followed by a field experiment to assess factors affecting peatland GPP and whether these could be detected by remote sensing data. The final part of this project involved the development of a Temperature and Greenness (TG) model using remote sensing to estimate GPP across blanket bog ecosystems. The project used both flux chamber and eddy covariance techniques to measure carbon uptake and compared the results to spectral reflectance at small-scale using a hand-held spectrometer, and large-scale using satellite data from MODIS. The results from these experiments suggest that spectral indices, and models using them, can give information about Sphagnum drought stress, seasonal change in peatland vegetation, and restoration progress, and are functional at scales from a few centimetres up to one kilometre. Next steps could include calibrating the developed model for a range of sites to broaden its applicability, and further work into monitoring water table depth using remote sensing
Declining Summertime Local‐Scale Precipitation Frequency Over China and the United States, 1981–2012: The Disparate Roles of Aerosols

The local‐scale precipitation (LSP) is mainly driven by thermal convection. Here we reveal a decreasing trend in the summertime LSP frequency over both China and the United States by utilizing the hourly rain gauge data from 1981 to 2012. The contrasting aerosol trend likely contributes to this same declining trend of LSP in both countries. As aerosol optical depth (AOD) goes beyond the turning zone of 0.25–0.30, the impact of aerosol on precipitation changes from invigoration to suppression. The mean AOD is generally less and larger than this range and of opposite trends in China and United States, respectively, which likely accounts for the same declining trend of LSP hours in the two countries. The observed boomerang shape points to the importance of aerosol loading, which matters as much as, if not more than the AOD trend, thereby potentially serving as a constraint for climate model evaluation.
First assessment on suspension parameter optimization for a solar – powered vehicle

Optimization of suspension parameters with respect to comfort and road holding is a challenging issue for solar–powered cars, due to in–wheel electric engines on very light vehicles, carrying payloads which can exceed their total mass. The solar–powered car considered in this study was designed and manufactured for racing by the University of Bologna; with a mass of 300 kg and a payload of 320 kg due to four occupants, using 5 m2 of monocrystalline silicon photovoltaic panel on the roof, 64 kg of lithium–ion batteries and two electric engines coupled directly to the rear wheels, it can achieve either a range of 600 km at cruising speed, or velocity peaks of 120 km/h. In this contribution, equivalent vertical stiffness and equivalent damping coefficients are optimized for both axles, achieving results that in terms of comfort and road holding are comparable to those of standard passenger cars.
Landscapes of the apes: modelling landscape use of chimpanzees and early hominins across an environmental gradient.

As primate habitat is declining rapidly, studying the flexibility of primates to adapt to changing landscapes is important. Landscape-scale studies of primate habitat use are, however, scant. Predictive models can provide important tools in investigating primate landscape use. Chimpanzees (Pan troglodytes) face habitat loss throughout their range, but their susceptibility to change remains unclear. Changing landscapes also played a vital role in human evolution, but evidence on early hominin behaviour remains limited. Chimpanzee responses to changing landscapes may provide new insights into early hominin landscape use due to chimpanzees’ close relatedness to humans. This thesis used individual-based and referential modelling to explore hominid (i.e. chimpanzee, Ardipithecus ramidus and Australopithecus anamensis/ afarensis) landscape use along an environmental gradient from forests to savannahs to determine their adaptability to change. Based on literature review, this thesis first quantitatively defined chimpanzee landscapes as dense forests, forest mosaics and savannahs using vegetation and climate data. Relationships between chimpanzee behaviour and habitat were identified based on literature and expert reviews. Data were used to set out rules for a NetLogo individual- based model on chimpanzee landscape use. Model output highlighted differences in activity budgets, internal states and daily path lengths for chimpanzees in forests, mosaics and savannahs due to the availability of resources. Maintaining homeostasis was increasingly more difficult in more open landscapes. A savannah chimpanzee case study model based on field data for Issa, Tanzania, verified these findings and showed that savannah chimpanzees faced particular survival challenges; additional adaptations were necessary for survival. Using a referential modelling approach and adapting the chimpanzee models to suit early hominin diet and morphology, early hominin landscape use models highlighted that, similar to chimpanzees, early hominins struggled more in savannahs than in forests. Early hominins were, however, more successful in maintaining homeostasis and more optimally used open vegetation as compared to chimpanzees, due to their morphological adaptations to a wider dietary breadth and bipedality, providing greater locomotor efficiency and better thermoregulatory abilities. Australopithecus was more successful than Ardipithecus. This research thus quantitatively characterised the selective pressures that shape hominid landscape use, and thereby provided a unique contribution to primatology and human origin studies. Models have important applications for conservation and further research, such as exploring the environmental context of hominid evolution and predicting the impacts of various landscape changes on hominid survival.
Genetic Determinants of Circulating Glycine Levels and Risk of Coronary Artery Disease

Background Recent studies have revealed sexually dimorphic associations between the carbamoyl‐phosphate synthase 1 locus, intermediates of the metabolic pathway leading from choline to urea, and risk of coronary artery disease (CAD) in women. Based on evidence from the literature, the atheroprotective association with carbamoyl‐phosphate synthase 1 could be mediated by the strong genetic effect of this locus on increased circulating glycine levels. Methods and Results We sought to identify additional genetic determinants of circulating glycine levels by carrying out a meta‐analysis of genome‐wide association study data in up to 30 118 subjects of European ancestry. Mendelian randomization and other analytical approaches were used to determine whether glycine‐associated variants were associated with CAD and traditional risk factors. Twelve loci were significantly associated with circulating glycine levels, 7 of which were not previously known to be involved in glycine metabolism (ACADM,PHGDH,COX18‐ADAMTS3,PSPH,TRIB1,PTPRD, and ABO). Glycine‐raising alleles at several loci individually exhibited directionally consistent associations with decreased risk of CAD. However, these effects could not be attributed directly to glycine because of associations with other CAD‐related traits. By comparison, genetic models that only included the 2 variants directly involved in glycine degradation and for which there were no other pleiotropic associations were not associated with risk of CAD or blood pressure, lipid levels, and obesity‐related traits. Conclusions These results provide additional insight into the genetic architecture of glycine metabolism, but do not yield conclusive evidence for a causal relationship between circulating levels of this amino acid and risk of CAD in humans.
Deformation associated with sliver transport in Costa Rica: seismic and geodetic observations of the July 2016 Bijagua earthquake sequence

Tectonic slivers form in the overriding plate in regions of oblique subduction. The inner boundaries of the sliver are often poorly defined and can consist of well-defined faults, rotating blocks or diffuse fault systems, which pass through or near the volcanic arc. The Guanacaste Volcanic Arc Sliver (GVAS) as defined by Montero et al., is a segment of the Central American Forearc Sliver, whose inner boundary is the ∼87-km-long Haciendas-Chiripa fault system (HCFS), which is located ∼10 km behind the volcanic arc and consists of strike slip faults and pull apart steps. We characterize the current ground motion on this boundary by combining earthquake locations and focal mechanisms of the 2016 Bijagua earthquake sequence, with the surface ground deformation obtained from Interferometric Synthetic Aperture Radar (InSAR) images from the ALOS-2 satellite. The coseismic stack of interferograms show ∼6 cm of displacement towards the line of sight of the satellite between the Caño Negro fault and the Upala fault, indicating uplift or SE horizontal surface displacement. The largest recorded earthquake of the sequence was Mw 5.4, and the observed deformation is one of the smallest earthquakes yet detected by InSAR in the Central American region. Forward and inverse models show the surface deformation can be partially explained by slip on a single fault, but it can be better explained by slip along two faults linked at depth. The best-fitting model consists of 0.33 m of right lateral slip on the Caño Negro fault and 0.35 m of reverse slip on the Upala fault, forming a positive flower structure. As no reverse seismicity was recorded, we infer the slip on the Upala fault occurred aseismically. Observations of the Bijagua earthquake sequence suggests the forearc sliver boundary is a complex and diffuse fault system. There are localized zones of transpression and transtension and areas where there is no surface expression suggesting the fault system is not yet mature. Although aseismic slip is common on subduction interfaces and mature strike-slip faults, this is the first study to document aseismic slip on a continental tectonic sliver boundary fault.
Group velocity maps using subspace and Trans-dimensional inversions: ambient noise tomography in the Western part of Java, Indonesia

In this paper, we compare two different methods for group velocity inversion: iterative, least-squares subspace optimization, and probabilistic sampling based on the Trans-dimensional Bayesian method with tree-based wavelet parameterization. The wavelet parameterization used a hierarchical prior for wavelet coefficients which could adapt to the data. We applied these inversion methods for ambient noise tomography of the western part of Java, Indonesia. This area is an area prone to multiple geological hazards due to its proximity to the subduction of the Australia Plate beneath Eurasia. It is therefore important to have a better understanding of upper crustal structure to support seismic hazard and disaster mitigation efforts in this area. We utilized a new waveform dataset collected from 85 temporary seismometers deployed during 2016–2018. Cross-correlation of the waveform data was applied to retrieve empirical Rayleigh wave Green's functions between station pairs, and the spatial distribution of group velocity was obtained by inverting dispersion curves. Our results show that, although computationally expensive, the Trans-dimensional Bayesian approach offered important advantages over optimization, including more effective explorative of the model space and more robust characterization of the spatial pattern of Rayleigh wave group velocity. Meanwhile, the iterative, least-square subspace optimization suffered from the subjectivity of choice for reference velocity model and regularization parameter values. Our Rayleigh wave group velocity results show that for short (1–10 s) periods group velocity correlates well with surface geology, and for longer periods (13–25 s) it correlates with centers of volcanic activity.
Surface mass balance of Davies Dome and Whisky Glacier on James Ross Island, north-eastern Antarctic Peninsula, based on different volume-mass conversion approaches

This study presents surface mass balance of two small glaciers on James Ross Island calculated using constant and zonally-variable conversion factors. The density of 500 and 900 kg·m–3 adopted for snow in the accumulation area and ice in the ablation area, respectively, provides lower mass balance values that better fit to the glaciological records from glaciers on Vega Island and South Shetland Islands. The difference between the cumulative surface mass balance values based on constant (1.23 ± 0.44 m w.e.) and zonally-variable density (0.57 ± 0.67 m w.e.) is higher for Whisky Glacier where a total mass gain was observed over the period 2009–2015. The cumulative surface mass balance values are 0.46 ± 0.36 and 0.11 ± 0.37 m w.e. for Davies Dome, which experienced lower mass gain over the same period. The conversion approach does not affect much the spatial distribution of surface mass balance on glaciers, equilibrium line altitude and accumulation-area ratio. The pattern of the surface mass balance is almost identical in the ablation zone and very similar in the accumulation zone, where the constant conversion factor yields higher surface mass balance values. The equilibrium line altitude and accumulation-area ratio determined for the investigated glaciers differ by less than 2m and 0.01, respectively. The annual changes of equilibrium line altitude and the mean values determined over the period 2009–2015 for Whisky Glacier (311 ± 16 m a.s.l.) and Davies Dome (393 ± 18 m a.s.l.) coincide with the values reported from Bahía del Diablo Glacier on Vega Island but differ from the glaciological records on South Shetland Islands.
Elimination of Micropollutants in Activated Sludge Reactors with a Special Focus on the Effect of Biomass Concentration

This study aimed to investigate the effects of sludge retention time (SRT), hydraulic retention time (HRT), and biomass concentration (CTSS) in activated sludge systems on removal of various micropollutants (MPs), covering a wide spectrum of biodegradability. The influence of biomass concentration on the classical pseudo-first-order rate constant was verified. Results showed that the removal rate constants were affected by both the HRT and SRT. The enhancement of the SRT increased the removal of all the MPs except for two macrolide antibiotics. Application of a higher HRT also improved MP removal, as was expected from the measured removal rate constants. More interesting, our results indicated that, logically, the increase of biomass concentration (expressed as total suspended solids CTSS) from 3 to 5 gTSS L−1 significantly enhanced the removal rate of the highly and moderately degradable compounds. Conversely, a further increase to 8 gTSS L−1 produced only an unexpected moderate effect, showing that the rate was not proportional to biomass concentration, contrary to what is generally postulated. Therefore, the use of classical kinetic models is questionable, since they do not cover the entire range of boundary conditions in activated sludge systems. This work opens new research paths and suggests potential improvements to processes.
Identification of deep coal seam families using machine learning

Summary The Cooper Basin of Australia is a world-class unconventional gas resource with estimated gas resources of 29.8 trillion cubic feet. However, the production of this gas is challenging as the significant gas resources are located in deep coal seams, which are poorly cleated and characterised by extremely low matrix permeability. Feasibility of gas production from the Cooper Basin Deep Coal Gas (CBDCG) play was demonstrated by Santos; however, its commercial viability is yet to be proven. Recent studies provided a new insight into the gas generation ability of Cooper Basin coal seams and showed that multiple environmental features affect gas concentration and flow capacity. Fortunately, a large historical dataset exists and includes wireline and mud log data from wells drilled in the Cooper Basin. Up to 10,000 individual coal seams were identified in 1400 wells and various parameters of individual reservoir intersections, which include gas in place, thermal maturity, temperature and other petrophysical readings, completed the Cooper Basin Deep Coal Reservoir (CBDCR) database. Such a database is suitable for assessing the potential of the ultradeep Permian coal gas reservoirs of the Cooper Basin using machine learning. In this study, we explore the data using traditional statistical methods and propose a hierarchical clustering procedure to identify various coal seam families. The quality of the identified coal seams families (clusters) is then examined by domain experts. The gas in place, geomechanical parameters, pore pressure and other important for successful production parameters can be further assessed for all confirmed clusters.
Seismic Structure of the Antarctic Upper Mantle Imaged with Adjoint Tomography

The upper mantle and transition zone beneath Antarctica and the surrounding oceans are among the poorest‐imaged regions of the Earth's interior. Over the last 15 years, several large broadband regional seismic arrays have been deployed, as have new permanent seismic stations. Using data from 297 Antarctic and 26 additional seismic stations south of ~40°S, we image the seismic structure of the upper mantle and transition zone using adjoint tomography. Over the course of 20 iterations, we utilize phase observations from three‐component seismograms containing P, S, Rayleigh, and Love waves, including reflections and overtones, generated by 270 earthquakes that occurred from 2001–2003 and 2007–2016. The new continental‐scale seismic model (ANT‐20) possesses regional‐scale resolution south of 60°S. In East Antarctica, thinner continental lithosphere is found beneath areas of Dronning Maud Land and Enderby‐Kemp Land. A continuous slow wave speed anomaly extends from the Balleny Islands through the western Ross Embayment and delineates areas of Cenozoic extension and volcanism that span both oceanic and continental regions. Slow wave speed anomalies are also imaged beneath Marie Byrd Land and along the Amundsen Sea Coast, extending to the Antarctic Peninsula. These anomalies are confined to the upper 200–250 km of the mantle, except in the vicinity of Marie Byrd Land where they extend into the transition zone and possibly deeper. Finally, slow wave speeds along the Amundsen Sea Coast link to deeper anomalies offshore, suggesting a possible connection with deeper mantle processes.