Distinguishing radioactive xenon detections that originate from reactor sources remains a key challenge of radioxenon monitoring for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). This was also crucial for the interpretation of radioxenon detections in the aftermath of the announced North Korean nuclear test explosions. Due to its geo-location, the noble gas system JPX38 at the International Monitoring System radionuclide station RN38, Takasaki, played an important role for that. At JPX38 several episodes of recurring high radioxenon activity concentration peaks were observed in 2024/2025. We investigate the common source region of those peaks by stacking sensitivities derived by backward atmospheric transport modeling. The sole maximum of coincidence points to the area of the Yongbyon nuclear complex in North Korea where the Experimental Light Water Reactor started operation in October 2023.
This paper develops an observation-constrained rapid ground-motion simulation method based on the Stochastic Method Simulation (SMSIM), aiming to improve the representation of spatial variations in ground-motion parameters when finite-fault geometry is not available in the early post-earthquake stage. This modified method enables reliable and rapid construction of ground motion fields even in the absence of detailed finite fault information. By using the spatial distribution characteristics of the 5
Desert and desertified regions are increasingly affected by environmental degradation driven by climate change and unsustainable land use. Despite extensive remote-sensing research on drylands, comparative assessments using a natural hyper-arid desert as an ecological reference for evaluating a rehabilitated desertified landscape remain limited. This study investigates whether temporal changes in vegetation and land-surface spectral trajectories around the 2018 rehabilitation onset differ across multiple indicators and how these trajectories compare with those of a natural desert ecosystem. The analysis covers 2001–2024, using MODIS observations to characterize long-term spectral dynamics, with statistical trend analyses conducted for 2001–2022, and Sentinel-2 imagery from 2019 to 2024 to provide high-resolution spatial information. Vegetation, moisture conditions, and bare-soil exposure were compared between the Kavir Desert, Iran, representing a natural hyper-arid reference ecosystem, and the Iğdır Combating Erosion and Desertification Area, Türkiye, representing a semi-arid landscape undergoing ecological rehabilitation. Multitemporal Sentinel-2 and MODIS data were used to calculate five spectral indices: the Bare Soil Index (BSI), Moisture Stress Index (MSI), Normalized Difference Vegetation Index (NDVI), Soil-Adjusted Vegetation Index (SAVI), and Normalized Difference Water Index (NDWI). MSI and NDWI were interpreted as spectral proxies for vegetation moisture stress and surface moisture-related conditions, respectively, rather than as direct measurements of soil or atmospheric moisture. Temporal trends and differences between the two study areas were evaluated using the trend-free pre-whitening Mann–Kendall (TFPW-MK) test, Sen’s slope estimator, and the non-parametric paired Wilcoxon signed-rank test, while an interrupted time-series (ITS) analysis was used to assess changes in spectral-index trajectories around the 2018 rehabilitation onset. The Iğdır area exhibited significantly greater vegetation density and lower bare-soil exposure than the Kavir Desert, with median NDVI values of 0.1291 and 0.0697, respectively (p < 0.001), and median BSI values of 0.0983 and 0.2059, respectively (p < 0.001). Vegetation moisture stress was also substantially higher in the Kavir Desert (median MSI = 1.2391) than in Iğdır CDA (median MSI = 1.0265), whereas NDWI-derived surface moisture-related conditions differed significantly between the regions (p < 0.001). The interrupted time-series analysis revealed heterogeneous temporal responses around the 2018 rehabilitation onset. NDVI exhibited a significant positive level shift at the onset of the rehabilitation period, but this was followed by a significant negative post-2018 trend, while MSI showed a significant negative change in its post-2018 trajectory. No significant intervention-associated trend changes were detected for BSI, NDWI, or SAVI. These temporal changes should be interpreted as being associated with the rehabilitation period rather than as direct causal effects of restoration, given the potential influence of concurrent climatic variability, localized irrigation, vegetation composition, and other environmental factors. These findings demonstrate the value of natural hyper-arid deserts as ecological reference systems for evaluating rehabilitation-related ecological trajectories and highlight the potential of multi-scale remote sensing for monitoring dryland degradation and heterogeneous environmental responses to rehabilitation.
This study investigates long-term trends in annual maximum snow depth and evaluates the adequacy of design snow loads prescribed by TS EN 1991–1-3 across nine meteorological stations in northeastern Türkiye over the period 1950–2023. Annual maximum snow depth series were analyzed using the Innovative Trend Analysis (ITA) and classical nonparametric tests, revealing a pronounced spatial dichotomy: high-elevation continental stations exhibit stable and persistent snow conditions, while coastal and basin stations are dominated by episodic extreme events and high interannual variability. Statistically significant decreasing trends were confirmed at Ardahan and Ağrı by all three classical tests, while ITA sub-class decomposition revealed severity-class-specific changes at additional stations that are undetectable by monotonic trend tests alone. Frequency analysis using station-optimized probability distributions enabled estimation of probable maximum snow depths for return periods up to 200 years. Equivalent snow loads calculated for the 50-year return period—consistent with the EN 1991–1-3 exceedance probability of 0.02—were compared against standard reference values, revealing systematic underestimation across the region. Under the settled snow density assumption of 3 kN/m3, all nine stations exceeded the prescribed thresholds, with station-specific correction factors reaching 4.88. To the best of our knowledge, this is the first study to directly link station-level probabilistic snow load estimates with a formal adequacy assessment of TS EN 1991–1-3 for this region, providing a quantitative basis for regionally calibrated revision of design snow load standards.
Seismic hazard in the Alborz region of northern Iran is predicated on the contoured relationships between fault configurations, the complied stress on fault planes, and the kinematic behavior of fault ruptures. We analyze the main parameters of seismicity and the regional hazard implications based on the comprehensive dataset of the IRSC containing 20,969 earthquakes from 2006 to 2024. After performing a frequency–magnitude study, a b-value of 0.71 ± 0.01 (Mc=2.3) was obtained, signifying a seismic regime with a chance of a large earthquake. Variation in a-value and b-value illustrates the complexity along fault systems as low b-value along the Khazar, North Alborz, Rudbar, and Masuleh faults is coupled with higher Mmax and stress concentration, marking the areas as seismically vulnerable due to the potential for large earthquakes. On the other hand, faults like Atari, Kandevan and North Tehran have low stress, yet are vulnerable over a long time to a slow strain accumulation. The combined use of fractal dimension (Dc), the likelihood of future events (Pr(M6 +)), and differential stress (Δσ) provides a more dynamic characterization of seismic hazard, in which fault geometry, event likelihood, and stress state jointly shape the hazard pattern. Totally, this multi-parameter approach offers a strengthened scientific basis for sophisticated hazard modeling while also underlining the necessity regarding the development of localized risk mitigation practices for the highly populated regions of northern Iran.
