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Heavy rain over eastern Kentucky during late July 2022 caused catastrophic flooding along the North Fork Kentucky River. A disproportionate number of the 45 deaths attributed to the flood occurred along or near Troublesome Creek, a tributary that has had 25 percent of its watershed affected by mountaintop removal coal mining over the last 40 years. Flood recurrence intervals at gages along the North Fork ranged from 94 years at Jackson to 2 years upstream at Hazard to 850-1,000 years farthest upstream at Whitesburg. The recurrence interval variability is consistent with the spatial distribution of rainfall during the event, which varied by a factor of 3 over the watershed upstream from Jackson. A topographically driven cumulative flux model based upon a cumulative precipitation map, a lidar digital elevation model, and absorption coefficients calibrated to streamflow and precipitation data show that Troublesome Creek contributed 35 percent of the cumulative discharge of the North Fork at the confluence from 28 percent of the upstream watershed area. Comparison of the calibrated model to a hypothetical model that assumes no mining-related reduction in absorption suggests the maximum increase in cumulative stream discharge during the flood potentially attributable to mountaintop removal mining is 22 percent along the North Fork at Whitesburg, 28 percent along the North Fork at Jackson, 41 percent along Troublesome Creek at its confluence with the North Fork, greater than 50 percent upstream along reaches adjacent to mined areas, and 50 to 150 percent in small tributaries emanating from mined areas. [ABSTRACT FROM AUTHOR]

Landslide susceptibility mapping (LSM) characterizes landslide potential, which is essential for assessing landslide risk and developing mitigation strategies. Despite the significant progress in LSM research over the past two decades, several long-standing issues, such as uncertainties related to training samples and model selection, remain inadequately addressed in the literature. In this study, we employed a physically based susceptibility model, PISA-m, to generate four different non-landslide data scenarios and combine them with mapped landslides from Magoffin County, Kentucky, for model training. We utilized two Bayesian network model structures, Naïve Bayes (NB) and Tree-Augmented Naïve Bayes (TAN), to produce LSMs based on regional geomorphic conditions. After internal validation, we evaluated the robustness and reliability of the models using an independent landslide inventory from Owsley County, Kentucky. The results revealed considerable differences between the most effective model in internal validation (AUC = 0.969), which used non-landslide samples extracted exclusively from low susceptibility areas predicted by PISA-m, and the models' unsatisfactory performance in external validation, as manifested by the identification of only 79.1% of landslide initiation points as high susceptibility areas. The obtained results from both internal and external validation highlighted the potential overfitting problem, which has largely been overlooked by previous studies. Additionally, our findings also indicate that TAN models consistently outperformed NB models when training datasets were the same due to the ability to account for variables' dependencies by the former. [ABSTRACT FROM AUTHOR]

Slow-moving, chronically destructive landslides are projected to grow in number globally in response to precipitation increases from climate change, and land disturbances from wildfire, mining and construction. In the Cincinnati and northern Kentucky metropolitan area, USA, landslides develop in colluvium that covers the steep slopes along the Ohio River and its tributaries. Here we quantify elevation changes in a slow-moving colluvial landslide over 14 years using county-wide lidar, uncrewed aerial vehicle (UAV) structure-from-motion (SfM) surveys and a UAV lidar survey. Because the technology and quality differ between surveys, the challenge was to calculate a threshold of detectable change for each survey combination. We introduce two methods; the first uses propagated elevation difference errors and the second back-calculates the individual survey errors. Thresholds of detection range from ±0.05 to ±0.20 m. Record rainfall in 2011 produced the largest vertical changes. Since then, the landslide toe has continued to deform, and the landslide has doubled its width by extending into a previously undisturbed slope. Although this study presents a technique to utilize older datasets in combination with modern surveys to monitor slow-moving landslides, it is broadly applicable to other studies where topographic data of differing quality are available. [ABSTRACT FROM AUTHOR]

Coseismic displacements estimated from comparison before-and-after satellite images suggest that the large and intermittently active landslide upon which the village of Laprak, Nepal, was built moved a geometric mean of 80 cm (95% mean confidence interval of 74–86 cm) or less during the 2015 Mw 7.8 Gorkha earthquake. The village was located about 6 km from the earthquake epicenter. We used published geotechnical and topographic data collected as part of a previous study of the landslide, publicly available earthquake information, and a physically plausible range of pre-monsoon dry season pore-pressure coefficients to constrain Monte Carlo simulations based on six published simplified Newmark models of coseismic displacement in natural slopes. Kolmogorov–Smirnov statistics show that five of the models produced coseismic displacement distributions in good to marginal agreement with our satellite image measurements. A seventh result obtained by combining results from the six individual models to balance the strengths and weaknesses of each also produced good agreement. The agreement between our observed and simulated results suggests that simplified Newmark models may be reliable tools for reconnaissance level earthquake hazard assessment in mountainous areas if probabilistic approaches are used to account for input parameter uncertainty. [ABSTRACT FROM AUTHOR]

Vertical deflection profiles derived from microradian-sensitivity tiltmeter data collected over a 1 yr period suggest that an earth fissure in the subsiding Mimbres Basin is located near the inflection point of an evolving surficial fold of infinitesimal amplitude. Water levels beneath the study site also fell steadily during the period of observation. Calculated curvature profiles, which reflect the sign and relative magnitude of fiber strain along the ground surface, further imply that the fissure was within a zone of contraction throughout the study period. Observed fissure-perpendicular tilts and the location of the fissure at an inflection point rather than along an anticlinal crest are consistent with a mode II fracture (shearing mode crack or fault) rather than a mode I fracture (opening mode crack or joint). Tilting parallel to the fissure further suggests a component of mode III (tearing-mode crack) displacement during the study period. Thus, the three-dimensional displacement, strain, and stress fields around the fissure were considerably more complicated than those suggested by previous fissure monitoring studies and suggest that the fissure may have been formed in compression as a shear crack rather than in tension as an extensional crack. On the basis of the occurrence of right steps in the trace of the fissure, we speculate that our data may reflect contraction across one of the steps as a consequence of left-lateral slip along the fissure.

VS30 is currently used as a key proxy to parameterize site response in engineering design and other applications. However, it has been found that VS30 is not an appropriate proxy, because it does not reliably correlate with site response. Therefore, the VS30-based National Earthquake Hazards Reduction Program site maps may not capture regional site responses. In earthquake engineering, site resonance, which can be characterized by the fundamental mode with a site period (⁠Tf⁠) and its associated peak amplification (⁠A0⁠), is the primary site-response concern. Mapping Tf and A0 is thus essential for accurate regional seismic hazard assessment. We developed a 3D shear-wave velocity model for the Jackson Purchase Region of western Kentucky, based on shear-wave velocity profiles interpreted from seismic reflections and refractions, mapped geologic units, and digital-elevation-model datasets. We generated shear-wave velocity profiles at grid points with 500 m spacing from the 3D model and performed 1D linear site-response analyses to obtain Tf and A0⁠, which we then used to construct contour maps for the study area. Our results show that Tf and A0 maps correlate with the characteristics of regional geology in terms of sediment thicknesses and their average shear-wave velocities. We also observed a strong dependency of A0 on bedrock shear-wave velocities. The mapped Tf and A0 are consistent with those estimated from borehole transfer functions and horizontal-to-vertical spectral ratio analyses at broadband and strong-motion stations in the study area. Our analyses also demonstrate that the depth to bedrock (⁠Zb⁠) is correlated to Tf⁠, and the average sediment shear-wave velocity (⁠VS-avg⁠) is correlated to A0⁠. This implies that Zb and VS-avg may be considered as paired proxies to parameterize site resonance in the linear-elastic regime. [ABSTRACT FROM AUTHOR]