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Abstract Solifluction processes in the Arctic are highly complex, introducing uncertainties in estimating current and future soil carbon storage and fluxes, and assessment of hillslope and infrastructure stability. This study aims to enhance our understanding of triggers and drivers of soil movement of permafrost-affected hillslopes in the Arctic. To achieve this, we established an extensive soil deformation and temperature sensor network, covering 48 locations across multiple hillslopes within a 1 km² watershed on the Seward Peninsula, AK. We report depth-resolved measurements down to 1.8 m depth for May to September 2022, a period conducive to soil movement due to deepening thaw layers and frequent rain events. Over this period, surface movements of up to 334 mm were recorded. In general, these movements occur close to the thawing front, and are initiated as thawing reaches depths of 0.4 to 0.75 m. The largest movements were observed at the top of the south-east facing slope, where soil temperatures are cold (mean annual soil temperatures averaging -1.13°C) and slopes are steeper than 15°. Our analysis highlights three primary factors influencing movements: slope angle, soil thermal conditions, and thaw depth. The latter two significantly impact the generation of pore water pressures at the thaw–freeze interface. Specifically, soil thermal conditions govern the liquid water content, while thaw depth influences both the height of the water column and, consequently, the pressure at the thawing front. These factors affect soil properties, such as cohesion and internal friction angle, which are crucial determinants of slope stability. This underscores the significance of a precise understanding of subsurface thermal conditions, including spatial and temporal variability in soil temperature and thaw depth, when assessing and predicting slope instabilities. Based on our observations, we developed a Factor of Safety proxy that consistently falls below the triggering threshold for all probes exhibiting displacements exceeding 50 mm. This study offers novel insights into patterns and triggers of hillslope movements in the Arctic and provides a venue to evaluate their impact on soil redistribution.

Both fast and slow earthquakes are preceded by micro-failure events that radiate energy. According to machine learning, these events can foretell catastrophic failure in laboratory experiment earthquakes.

The creep behavior of rocks has been broadly researched because of its extensive application in geomechanics. Since the time-dependent stability of underground constructions is a critical aspect of geotechnical engineering, a comprehensive understanding of the creep behavior of rocks plays a pivotal role in ensuring the safety of such structures. Various factors, including stress level, temperature, rock damage, water content, rock anisotropy, etc., can influence rocks’ creep characteristics. One of the main topics in the creep analysis of rocks is the constitutive models, which can be categorized into empirical, component, and mechanism-based models. In this research, the previously proposed creep models were reviewed, and their main characteristics were discussed. The effectiveness of the models in simulating the accelerated phase of rock creep was evaluated by comparing their performance with the creep test results of different types of rocks. The application of rock’s creep analysis in different engineering projects and adopting appropriate creep properties for rock mass were also examined. The primary limitation associated with empirical and classical component models lies in their challenges when it comes to modeling the tertiary phase of rock creep. The mechanism-based models have demonstrated success in effectively simulating the complete creep phases; nevertheless, additional validation is crucial to establish their broader applicability. However, further investigation is still required to develop creep models specific to rock mass. In this paper, we attempted to review and discuss the most recent studies in creep analysis of rocks that can be used by researchers conducting creep analysis in geomechanics.HighlightsCreep constitutive models for rocks were reviewed, and their main characteristics were discussed.The applications of creep analysis in geomechanics were explained, and some engineering projects were mentioned.The back analysis techniques using long-time measured monitoring data were successfully used for finding rock mass creep parameters.

Continuous seismic signal, filtered out by machine-learning methods, could help infer fault displacement in the Cascadia subduction zone.

One of the outstanding problems in understanding the behavior of intermediate-to-silicic magmatic systems is the mechanism(s) by which large volumes of crystal-poor rhyolite can be extracted from crystal-rich mushy storage zones in the mid-deep crust. The mechanisms commonly invoked are hindered settling, micro-settling, and compaction. The concept of micro-settling involves extraction of grains from a crystal framework during Ostwald ripening and has been shown to be non-viable in the metallic systems for which it was originally proposed. Micro-settling is also likely to be insignificant in silicic mushes, because ripening rates are slow for quartz and plagioclase, contact areas between grains in a crystal mush are likely to be large, and abundant low-angle grain boundaries promote grain coalescence rather than ripening. Published calculations of melt segregation rates by hindered settling (Stokes settling in a crystal-rich system) neglect all but fluid dynamical interactions between particles. Because tabular silicate minerals are likely to form open, mechanically coherent, frameworks at porosities as high as ~ 75%, settling of single crystals is only likely in very melt-rich systems. Gravitationally-driven viscous compaction requires deformation of crystals by either dissolution–reprecipitation or dislocation creep. There is, as yet, no reported microstructural evidence of extensive, syn-magmatic, internally-generated, viscous deformation in fully solidified silicic plutonic rocks. If subsequent directed searches do not reveal clear evidence for internally-generated buoyancy-driven melt segregation processes, it is likely that other factors, such as rejuvenation by magma replenishment, gas filter-pressing, or externally-imposed stress during regional deformation, are required to segregate large volumes of crystal-poor rhyolitic liquids from crustal mushy zones.

Most aftershocks occur in areas experiencing large co‐seismic stress changes, yet some occur long after the mainshock in remote lightly stressed regions. The triggering mechanism of these remote delayed aftershocks is not well understood. Here, we study aftershocks occurring in the Dead Sea (DS) area following the 2023 Mw7.8 and Mw7.6 Kahramanmaraş earthquakes. Most aftershocks cluster along previously quiescent structures off‐ the main DS fault strand. Visual inspection disclosed three aftershocks instantaneously triggered by the Mw7.6 in the northern DS basin, and match‐filtering revealed a delayed aftershock. Waveform similarity and temporal clustering suggest the northern DS aftershocks re‐rupture a stick‐slip patch loaded by surrounding creep. Velocity‐gradient seismograms show the Mw7.6 exerted larger transient stresses than the Mw7.8, which may explain triggering by the Mw7.6, but not by the Mw7.8. This account of instantaneously triggered repeaters underscores the role of interactions between aseismic and seismic slip in remote triggering. Plain Language Summary Most aftershocks occur in areas experiencing large co‐seismic permanent stress changes, yet some occur long after the mainshock in remote regions experiencing small stress changes. The physics controlling the triggering of remote delayed aftershocks is not well understood. Here, we report on remotely triggered aftershocks in the Palestine Territories and Israel following the 2023 Kahramanmaraş earthquake pair. The main fault within the study area is the Dead Sea (DS) Transform (DST), yet most aftershocks occur on secondary structures located off‐ the main DST fault strand. This indicates off‐fault structures are presently more pre‐stressed than the main DST fault, which has important implications for seismic hazard analysis. We document a sequence of four aftershocks re‐rupturing the same fault patch in the Northern DS basin. Three of these aftershocks were triggered during the Mw7.6 surface‐wave passage, and one aftershock is delayed. We do not observe triggering in the study area due to the larger and closer Mw7.8. The non‐triggering by the Mw7.8 and later triggering by the Mw7.6 is explained in terms of the mainshock source properties. The aftershock decay rates and moments are consistent with a model in which a stick‐slip patch is being loaded by creep in the surrounding area. Key Points We document a dramatic earthquake rate increase in the Palestine Territories and Israel following the 2023 Kahramanmaraş earthquakes We provide the first account of instantaneous remotely triggered repeating aftershocks triggered by the Mw7.6 mainshock Non‐triggering by the Mw7.8 and later triggering by the Mw7.6 underscores the role of aseismic and seismic fault slip interactions

This article investigates the usage of terrestrial laser scanner (TLS) point clouds for monitoring the gradual movements of soil masses due to freeze–thaw activity and water saturation, commonly referred to as solifluction. Solifluction is a geomorphic process which is characteristic for hillslopes in (high-)mountain areas, primarily alpine periglacial areas and the arctic. The movement can reach millimetre-to-centimetre per year velocities, remaining well below the typical displacement mangitudes of other frequently monitored natural objects, such as landslides and glaciers. Hence, a better understanding of solifluction processes requires increased spatial and temporal resolution with relatively high measurement accuracy. To that end, we developed a workflow for TLS point cloud processing, providing a 3D vector field that can capture soil mass displacement due to solifluction with high fidelity. This is based on the common image-processing techniques of feature detection and tracking. The developed workflow is tested on a study area placed in Hohe Tauern range of the Austrian Alps with a prominent assemblage of solifluction lobes. The derived displacements were compared with the established geomonitoring approach with total station and signalized markers and point cloud deformation monitoring approaches. The comparison indicated that the achieved results were in the same accuracy range as the established methods, with an advantage of notably higher spatial resolution. This improvement allowed for new insights considering the solifluction processes.

Forecasting landslide inundation upon catastrophic failure is crucial for reducing casualties, yet it remains a long‐standing challenge owing to the complex nature of landslides. Recent global studies indicate that catastrophic hillslope failures are commonly preceded by a period of precursory creep, motivating a novel scheme to foresee their hazard. Here, we showcase an approach to hindcast landslide inundation by linking satellite‐captured precursory displacements to modeling of consequent granular‐fluid flows. We present its application to the 2021 Chunchi, Ecuador landslide, which failed catastrophically and evolved into a mobile debris flow after four months of precursory creep, destroying 68 homes along its lengthy flow path. Underpinned by uncertainty quantification and in situ validations, we highlight the feasibility and potential of forecasting landslide inundation damage using observable precursors. This forecast approach is broadly applicable for flow hazards initiated from geomaterial failures. Plain Language Summary One of the most effective approaches to reduce landslide damage, is somehow getting to know in advance where the target landslide is about to occur and how large the damage area will be when it occurs. Here, we show a possible solution of using satellite‐observed precursory motion to find and quantify the landslide source, and then input this information into a granular‐flow model to estimate its potential damage area when evolving into a debris flow. This seamlessly integrated method could allow to effectively inform hazard reduction, as large catastrophic landslides have been widely observed to manifest precursory destabilization weeks to months before the final failure. As a representative example, we applied this approach to the 2021 Chunchi, Ecuador landslide event and found it highly effective for predicting landslide inundation based on both model uncertainty quantification and field validations. Key Points Satellite radar and optical observations uncover precursory landslide motion to infer source area and volume We propose an approach to forecast landslide inundation through seamless integration of precursory motion and granular‐flow modeling Uncertainty quantification and in situ validations corroborate the effectiveness of this forecast approach

Aiming at the disadvantage that the traditional creep model cannot describe the nonlinear creep acceleration stage (third-order creep stage) of rock. This paper explains the creep process of salt rock from a microscopic perspective based on the Riemann–Liouville type fractional-order calculus operator theory and acoustic emission (AE) theory, and describes the creep process of salt rock with the improved fractional-order derivatives. The results of uniaxial creep damage tests on rock salt specimens under quasi-static loading conditions are given, complete creep damage curves are obtained, and a creep model based on fractional-order derivatives for viscoelastic damage of salt rock is proposed, and finally, the best variable values are fitted to determine the optimum values. The AE characteristic parameter curves were compared with the creep strain curves, and it was found that the AE characteristic curves could predict the time point when the salt rock enters the accelerated creep stage in advance. According to this time point, the model is fitted in sections and compared with the experimental results. The predicted value of the model is in good agreement with the test results, and can better describe the nonlinear accelerated creep stage of salt rock. It is believed that the fractional-order model can simulate the whole process of rock creep well and has good practical application value.Highlights•Established a viscoelastic-plastic damage creep model of rock salt based on fractional derivative.•Based on AE technique, the creep process of rock salt was explained from the microscopic perspective and the damage evolution was obtained.•The AE characteristic curve can predict the time point when the salt rock enters the accelerated creep stage in advance, and the model can be fitted to the segment according to this time point, which can better describe the nonlinear accelerated creep stage of the salt rock.•Segmental fitting can well simulate the whole process of salt rock creep, has good superiority and reliable, which can predict engineering disaster in advance.

The experimental results show that initial damage has a clear effect on the creep behavior of rock. However, among the current creep models for rock, few consider the effect of the initial damage state. In the present study, a new nonlinear creep damage model for rock is proposed based on multi-loading creep tests of sandstone with different initial damage levels. The new model is composed of four components, a Hooke body, a Kelvin body, an improved viscous element, and a new nonlinear visco-plastic damage component. The creep damage model can not only describe the three typical creep stages (primary creep, secondary creep and tertiary creep) but also show the effect of initial damage on the creep failure stress. The parameters of the nonlinear creep damage model are obtained using the nonlinear least squares method. A unified set of creep parameters is proposed to predict the creep behavior of sandstone in different initial damage states. The agreement between the experimental data and numerical prediction demonstrates the applicability of the proposed model.