Universidad Técnica Federico Santa María

Identifying and distinguishing induced seismicity from background regional tectonic activity remains a major challenge within tectonically active settings, due to the overlap between natural seismicity and seismicity potentially triggered by human activities. Induced seismicity refers to earthquakes generated or modulated by anthropogenic processes such as reservoir impoundment, fluid injection or extraction, and mining. While mining-induced seismicity has been shown to increase seismicity rates and magnitudes in tectonically stable regions, fundamental uncertainties remain regarding the spatial extent of mining influence and its detectability in areas with high background tectonic activity. The case of study is in the Central Andes (18-36°S), in the Chilean Andean Margin. Here, long-lived subduction has shaped well-defined metallogenic belts hosting major metallic ore deposits, within which Chile has developed a long history of open-pit and underground mining across diverse geological and operational settings. We use regional crustal seismicity from a recently published regional seismic catalog, together with a database of large-scale open-pit and underground mining operations in Chile, to systematically evaluate spatial and statistical relationships between seismicity patterns and mining activity. Specifically, we apply a three-phase framework to identify seismic events with a higher likelihood of mining-induced origin. We first define a 15 km depth threshold to separate shallow seismicity potentially influenced by mining from deeper regional tectonic events, and distinguish near-field from far-field seismicity based on proximity to mining operations. We then apply a nearest-neighbor clustering method to identify stochastically independent events, which are more likely to be induced. Finally, distance to mines and clustering information are combined into a linear weighted metric that quantifies the likelihood of induced seismicity. The results reveal a marked daily temporal anomaly in shallow seismic behavior (depth < 15 km), where an increase in activity is observed in the near field of mines between 16:00 and 22:00, aligning with the mines’ primary operational windows and blasting schedules. Within this time window, the probability of events belonging to a tectonic cluster decreases, thereby increasing the likelihood that they are induced seismicity rather than aftershock sequences. The primary finding highlights a daily six-hour window that concentrates 70% of the total seismic activity in the near field of mines. This represents a concentration 2.8 times higher than normal compared to regional seismicity, which lacks a preferred time frame. These observations indicate that mining activities can impose a measurable temporal signature on seismicity, even within a tectonically active subduction margin, contributing to the broader understanding of how anthropogenic processes interact with natural seismic systems.

The bioconversion of fish by-products has been evidenced as a sustainable process to convert food waste into high-value products. In the present study, protein hydrolysates were produced from fish by-products by different bioprocesses and evaluated as fertilizers in wheat (Triticum aestivum L.) on a nitrogen-equivalent basis. Fish by-products were processed through grinding prior to bioconversion. Enzymatic hydrolysis was performed using Alcalase at 55 °C, pH 6.5, and a 3-h reaction, while microbial conversion was assessed using a lactic culture at 40 °C, pH 6.5, and a 10-day culture. Hydrolysates obtained by enzymatic and microbial bioconversion were evaluated as fertilizers by adding 30 mg after 7 and 14 days to wheat seeds sown under controlled conditions. Protease and microbial hydrolysis generated high concentrations of α-amino groups, yielding 100 mM and 170 mM, respectively. The combined process exhibited a synergistic effect, yielding 226 mM of α-amino groups and 33% of protein recovery. Plant growth assays were conducted under controlled conditions using nitrogen-equivalent doses of each hydrolysate. Microbial and combined enzymatic-microbial hydrolysates generated average plant lengths of 52 cm and 54 cm compared to 44 cm in the control, while plant biomass reached 1.7 g and 2.3 g with microbial and combined enzymatic-microbial hydrolysates compared to 0.7 g in the control. Photosynthetic parameters remained within normal physiological ranges from 2.5 to 3.3 for performance index (PI) and from 0.78 to 0.80 for maximum quantum efficiency (Fv/Fm). The integration of enzymatic and microbial catalysis produced the most effective biostimulant activity, highlighting the value of combining enzymatic specificity with microbial metabolic versatility. These findings support fish-derived protein hydrolysates as efficient and eco-friendly fertilizers that are capable of improving plant growth while contributing to sustainable and integral utilization of natural resources.

Abstract This study develops parametric models for the correlation between vertical and horizontal components of spectral accelerations in the Chilean subduction zone. The models are based on seismic records from national databases and recent ground motion models developed for the region. The effects of magnitude, distance, site conditions, and model selection on correlations are evaluated and found to be negligible, supporting the use of a simplified formulation. The proposed models are compared to existing models developed for other regions, showing significant differences, especially for inslab earthquakes. Despite these differences, the impact on practical applications is limited due to the low sensitivity of hazard estimates to variations in correlation at low correlation values. The results are suitable for use in seismic hazard analyses that incorporate vertical ground motion, enabling more comprehensive assessments for structures sensitive to this component. The study highlights the importance of developing region-specific models and identifies future needs, including expanding local ground motion models to additional intensity measures and refining correlation functions to better capture differences between interface and inslab events.

We survey some results regarding semi-orthogonal decompositions on moduli spaces of vector bundles on a curve, with an emphasis on those that use the machinery of windows. We briefly outline some of the main ideas that make windows a crucial tool for these results.

Abstract A search for a pseudoscalar a produced in association with a top-quark pair, or in association with a single top quark plus a W boson, with the pseudoscalar decaying into b -quarks ( $$a\rightarrow b\bar{b}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>a</mml:mi> <mml:mo>→</mml:mo> <mml:mi>b</mml:mi> <mml:mover> <mml:mrow> <mml:mi>b</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> </mml:math> ), is performed using the full Run 2 data sample using a dileptonic decay mode signature. The search covers pseudoscalar boson masses between 12 and 100 GeV and involves both the kinematic regime where the decay products of the pseudoscalar are reconstructed as two standard b -tagged small-radius jets, or merged into a large-radius jet due to its Lorentz boost. No significant excess relative to expectations is observed. Assuming a branching ratio $$\text {BR}(a\rightarrow b\bar{b})=100\% $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>BR</mml:mtext> <mml:mo>(</mml:mo> <mml:mi>a</mml:mi> <mml:mo>→</mml:mo> <mml:mi>b</mml:mi> <mml:mover> <mml:mrow> <mml:mi>b</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>)</mml:mo> <mml:mo>=</mml:mo> <mml:mn>100</mml:mn> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> , the range of pseudoscalar masses between 50 and 80 GeV is excluded at 95% confidence level for a coupling of the pseudoscalar to the top quark of 0.5, while a coupling of 1.0 is excluded at 95% confidence level for the masses considered, with the coupling defined as the strength modifier of the Standard Model Yukawa coupling.

Obstructed atomic phases, with their realizations in systems of diverse dimensionality, have recently arisen as one of the topological states with greatest potential to show higher-order phenomena. In this work we report a special type of obstruction, known as orbital-mediated atomic obstruction, in monolayers of materials with spatial symmetry described by the space group $P$-$3m1$. By means of a minimal tight-binding model and first-principles calculations, we show that this obstructed phase is related to the mismatch of the charge centers coming from the atomic limit with respect to the centers that are obtained from a reciprocal space description. Although we find atomic limits that correspond with occupied atomic sites, orbital-mediated atomic obstruction requires the presence of orbitals that have no support in real space. In order to demonstrate the nontrivial character of the obstruction, we confirm the presence of a filling anomaly for finite geometries that is directly associated with the bulk configuration, and discuss the role of the boundary states and their underlying mechanism. Several material examples are presented to illustrate the ubiquity of these nontrivial responses and, in turn, to discuss the differences related to the particular ground state configuration. In addition, we perform a survey of materials and elaborate a list of candidate systems which will host this obstructed phase in monolayer form.