The receiver function H-κ stacking method is a common technique used to estimate crustal thickness and Vp/Vs ratios, which are important parameters for describing the structure and composition of the crust. However, when reverberating phases in sedimentary layers overprint arrivals from the Moho discontinuity, they often introduce significant biases into H-κ stacking estimates. In this paper, we propose an improved method for estimating crustal thickness and Vp/Vs ratios, based on a two-layer model with joint constraints on crustal thickness and Vp/Vs using receiver functions and gravity data. We validate this method through numerical experiments and two practical examples from the North China Craton. The results demonstrate that the proposed method eliminates the Moho arrival delay effect caused by sedimentary layers, thereby improving the estimation accuracy of crustal thickness and Vp/Vs.
The Bay of Algiers, an urban area exposed to high seismic hazard due to nearby active faults, has a complex geological and topographical framework. This study aims to characterize site-effects using three complementary methods: standard spectral ratio (SSR), horizontal/vertical spectral ratio from earthquakes (HVSRE) and ambient vibration (HVSRN), applied to a temporary network of nine stations covering the Bouzareah Massif and the eastern part of the Mitidja Basin. Analyses of 76 local earthquakes and ambient vibration reveal site-effects for all stations except the one installed on the flat bedrock. Inter-comparison of the three methods reveals a strong convergence of the identified fundamental frequencies, f0, at five stations regardless of the origin of the site-effects, whereas stations located in more complex and heterogeneous subsurface conditions show significant deviations. The divergences between SSR and HVSRE results highlight the sensitivity of the estimated site-response curves to the selected reference condition, while the SSR technique remains the most reliable for evaluating amplification at f0. Differences between HVSRE and HVSRN at several stations are mainly related to the wavefield composition of earthquake data (body waves) and ambient vibration (surface waves). An analysis of polarization highlights directional effects related to underground irregularities and relief. Inversion of Rayleigh wave ellipticity made it possible to estimate shear-wave velocity (VS) of the bedrock between 1030 and 2140 m/s, consistent with the nature of the rocks. The multi-method approach provides a robust framework for site-response characteristics, and the obtained results contribute to better seismic risk management in the region.
This study evaluates Seasonal Auto-Regressive Integrated Moving Average (SARIMA) techniques for predicting river discharge up to 12 months ahead. The Sava River, Serbia, was chosen as the test basin because it plays a crucial role in regional water resource management. However, accurate long-term discharge prediction is challenging due to climatic variability and non-stationarity in hydrological series. Monthly discharge series from 1926 to 2022 at the Sremska Mitrovica station were modeled and forecasted using SARIMA and compared with Zero-Order Forecasting (ZOF) and Random Forests. The selected SARIMA model predicted discharge with a normalised Root Mean Square Error of 21% and a normalised Mean Absolute Error of 16% calculated as a percentage of mean observed discharge. This study evaluates both classical stochastic methods (SARIMA) and machine learning (Random Forest) for the Sava and underscores the potential for improved hydrological predictions in the Western Balkans. Future research should incorporate additional covariates and apply these models to diverse river systems to enhance predictive accuracy.
The velocities of the compressional and shear waves (VP and VS) were determined for seven parallel Multichannel Analysis of Surface Waves (MASW) traverses within the upstream basin of Chaq-Chaq Dam in Sulaimani, Kurdistan Region- Iraq. These traverses were executed with a spacing of 2 meters (m) between the geophones. The objective of this study was to investigate subsurface geological features, determine the depth to bedrock, assess bedrock strength, calculate primary and shear wave velocities, and explore potential causes for the collapse of the constructed Chaq-Chaq Dam. Data was collected using Geometrics Seismodule Controller software and processed using ParkSeis Software. The velocity results indicate that the study area comprises three geological layers: a surface soil layer on top, a middle layer of rock fragments, and a limestone layer at the bottom. The calculated Poisson’s ratio based on VP and VS values for these three layers ranges between 0.35 and 0.39 for the first layer, 0.30 and 0.33 for the second layer, and 0.24 and 0.25 for the third layer. These results suggest that the first layer has relatively high values of Poisson’s ratio, indicating an incompetent soil layer. The second layer exhibits moderate values, suggesting a fairly competent layer of rock fragments, while the third layer has low values, indicating a well-competent limestone layer. The findings also highlight deficiencies in the dam’s design, particularly in the southern parts where most of the traverses show the presence of sinkholes. These sinkholes are likely caused by water infiltration during the rainy winter season. When water pressure is applied to the dam, these sinkholes in the southwestern portion could be attributed as the cause of the dam collapsing. Additionally, the dam side was not properly intertied with the rocks forming the right bank of the dam.
This research focuses on Özkonak and the surrounding area in the Avanos district, investigating the relationship between tectonic lineaments and the formation of goethite and malachite mineralisation. The study aims to clarify how structural geological features influence the formation processes of these secondary minerals. Recent advances in satellite technology have greatly improved the effectiveness of remote sensing in mineral exploration. The study combined field surveys with Landsat-8 OLI/TIRS satellite imagery, processed using Geomatica, ENVI, and ArcGIS, to investigate the relationship between geological-tectonic lineaments and mineralisation patterns. The results indicate a strong correlation between mineralisation and tectonic lineaments, with significant concentrations of goethite and malachite mineralisation found to the west of Özkonak. This is particularly evident in areas characterised by imbricated thrust faults. These formations are likely to be secondary in the oxidation zone, suggesting the presence of primary sulphide deposits. The occurrence of mineralisation coincides with regions of significant tectonic lineaments, as shown by rose diagrams derived from both field and satellite data. The analysis revealed that the ore veins' position was N830W/170SW. The average orientation of the ore veins aligns with the N80-900W and N30-500E trending lineaments. In addition, a satellite-based surface temperature map indicates higher temperatures in the mineralised areas, which corresponds with the lineament maps. The results of this study could greatly enhance the exploration of primary sulphide deposits, which are the source of secondary mineralisation.
