Formation-scale effective CO2 storage for the Tipam, Barail and Lakadong+Therria units of the Upper Assam Basin, NE India, is evaluated using a volumetric model corrected by formation-specific efficiency factors, Monte Carlo simulation and global Sobol' sensitivity analysis. Deterministic mean effective capacities are calculated to be 519 Mt, 150 Mt and 28 Mt, respectively, with a cumulative approximate to 697 Mt CO2. Probabilistic results show P50 capacities of 541.4 Mt, 148.7 Mt, and 33.9 Mt, respectively, with formation means of 552 Mt, 153 Mt, and 35.2 Mt, and a basin-scale mean approximate to 740 Mt CO2. Sobol' indices show storage efficiency (E) dominates variance (S1 approximate to 0.65-0.77), followed by porosity and thickness with moderate controls; and CO2 density with negligible influence. Geomechanical screening indicates required injection pressures of approximate to 20-25 MPa are well below estimated fracture thresholds of approximate to 40-50 MPa, providing similar to 40-45% safety margin.
The Potwar Basin is one of Pakistan's major hydrocarbon-producing basins, where Eocene carbonate and shale-rich successions are important for evaluating source and reservoir potential. The Nammal Formation is a key stratigraphic unit in this basin, yet its integrated petroleum potential remains insufficiently constrained. This study evaluates the source rock and reservoir characteristics of the Nammal Formation by integrating palynofacies, organic geochemical, and petrophysical analyses from the Nammal Gorge section and the Fimkassar oilfield. A total of 11 outcrop samples and 21 well-cutting samples were examined using palynofacies analysis, total organic carbon measurement, Rock-Eval pyrolysis, and well-log interpretation. Total organic carbon values range from 0.71 to 0.95 wt%, indicating poor to fair organic richness, while S2 values range from 1.23 to 2.70 mg HC/g rock, suggesting limited to moderate hydrocarbon generation potential. Hydrogen Index values of 164-401 mg HC/g TOC indicate mixed Type II-III kerogen with oiland gas-prone characteristics. Thermal maturity indicators, including T-max values of 437-442 degrees C and vitrinite reflectance values of 0.71-0.80% Ro, place the samples within the oil generation window. Palynofacies observations support these geochemical results and show a mixed assemblage of phytoclasts and amorphous organic matter. Petrophysical interpretation indicates limestone-dominated lithology, low shale volume, average water saturation of 25.75%, and hydrocarbon saturation of 74.25%. Overall, the Nammal Formation shows poor to fair source rock potential but moderate to good reservoir potential within the studied interval.
Despite being an economically developed sedimentary basin with significant oil and gas production, the North na Plain exhibits anomalously high intraplate seismicity for a densely populated region. On 26 March 2025, a M(L)4.6 earthquake struck Yongqing County, following a similar M(L)4.8 event in 2018. Both earthquakes occurred near the central region of the devastating 1679 M8 Sanhe-Pinggu earthquake and the seismically active Tianjin Gap, thus widespread public attention due to their tectonic implications. This paper conducted a comprehensive investigation the 2025 Yongqing earthquake's seismogenic structure through the following points. (1) Focal mechanisms inversion for the mainshock and three M-L >= 2.5 aftershocks, (2) the earthquake relocation by waveform cross-correlation, (3)the rupture direction estimation by centroid relative relocation and the spectral ratio technique. The results reveal that the 2025 M(L)4.6 earthquake ruptured a NE-striking, steeply dipping right-lateral strike-slip fault, with predominant SW-to-NE rupture propagation. This kinematic behavior shows striking similarity to the 2018 M(L)4.8 event, suggesting potential structural linkage. While both seismogenic faults remain unmapped in regional geological surveys, they tentially link with the Xiadian fault zone at mid-crustal levels. Nevertheless, our analysis reveals no conclusive evidence of structural continuity between these faults and the 1679 Sanhe-Pinggu earthquake rupture zone. The nearby Pleistocene-active Hexiwu Fault, which has historically produced only one M-5.5 earthquake recorded but exhibits persistent moderate seismicity, may be capable of generating larger ruptures in the future, highlighting the necessity intensified seismic monitoring within this area.
This study aims to resolve the paradox associated with the aspect parameter used in landslide susceptibility mapping. Although aspect is widely considered an important parameter in landslide studies, its influence is often not adequately reflected in susceptibility maps. Previous studies have generally attributed this limitation to interactions with other conditioning factors, whereas the effect of aspect classification itself has received little attention. In this study, 18 classification schemes, including 13 classifications commonly used in the literature and 5 newly proposed alternatives, were evaluated using 1,152 datasets. The success of each classification was assessed by comparing the landslide frequency distributions among its subclasses. The results demonstrate that Groups 2, 7, 9, 10, and 11 achieved success rates of approximately 50% or higher. Among these, Group 2 provided the most consistent and reliable performance with the fewest classification problems. The findings indicate that the effectiveness of the aspect parameter strongly depends on the selected classification scheme. Therefore, researchers who obtain unsatisfactory results using automatic aspect classifications may improve the predictive performance of landslide susceptibility maps by adopting alternative classification approaches.
The Sheringal region of Upper Dir, situated in the tectonically active Kohistan mountains of northern Pakistan, experiences frequent landslides due to steep slopes, monsoon rainfall, and anthropogenic influences. This study addresses the lack of localized susceptibility models by developing and evaluating a decision-support framework for assessing landslide susceptibility in the Sheringal region of northern Pakistan. Eleven causative factors, namely slope, lithology, rainfall, earthquake zones, distance to faults, elevation, NDVI, distance to streams, roads, TWI, and aspect, were weighted using the Analytical Hierarchy Process (AHP) and Weighted Overlay Mapping (WOM) approaches. An inventory of 71 landslides were marked from satellite data and field observations, which guided the calibration of the model results. Results identified slope as the dominant factor, followed by lithology and rainfall. Validation through ROC curves confirmed strong predictive accuracy (AHP AUC: 0.83; WOM AUC: 0.79). Landslide susceptibility maps from both approaches were developed and classified into low to high-risk zones. Both the AHP and WOM susceptibility maps revealed nearly consistent spatial distributions, the AHP model exhibited slightly better predictive capability based on the validation results, indicating that it offers a more precise assessment of landslide susceptibility in the studied region. Theses maps provide valuable information for identifying high risk regions and can support slope stabilization measures and land-use planning.
