Hasil untuk "Dynamic and structural geology"

Runlong Dong, Yingkang Yao, Yize Kang et al.

Ground vibrations induced by tunnel blasting can severely impact nearby infrastructure. Therefore, accurate prediction of peak particle velocity (PPV) is essential for ensuring structural safety and engineering sustainability. This study proposes a PPV prediction model based on the Least Squares Support Vector Machine (LSSVM), optimised by a novel Adaptive Stagnation Whale Optimisation Algorithm (ASWOA) . To address the limitations of the conventional WOA, a regionally dynamic threshold adjustment strategy based on stagnation counter is proposed. recording the number of consecutive iterations without improvement, and calculate the dynamic threshold by combining the decay coefficient to control the rate of change, thereby adaptively adjusts the trigger probability of spiral updates, improving global search capability. Compared with others models, the proposed method not only improves prediction accuracy but also ensure higher reliability in vibration prediction. Moreover, it provides an efficient tool for vibration control in tunnel blasting under complex geological conditions.

Benbo Sun, Mingjiang Deng, Yan Xu et al.

The realistic prediction or simulation of the seismic behaviour of critical structures is highly sensitive to many aspects, including the earthquake source, propagation path, region topography, geological conditions and local complex structural dynamic analysis system. However, integrating the above key factors in a framework for generating realistic ground motions (GMs) and conducting dynamic analyses at specific engineering sites remains challenging. This task necessitates assessing the crucial elements involved in the seismic design of hydraulic tunnels (HTs), with the ultimate objective of safeguarding human lives in areas prone to seismic activity. To achieve this objective, a multiscale framework leveraging the spectral element method (SEM) and finite element method (FEM) is proposed. This framework involves establishing a coupling strategy between the SEM and FEM to address geological media–structure interaction problems. The SEM is utilised to generate and propagate elastic waves within the soil, while the FEM allows the studied structure to be comprehensively represented. The coupling technique is implemented using the weak‐coupling strategy in conjunction with the time domain reduction method (DRM). Then, a series of dynamic analyses and seismic performance assessments of the HT with the coupling SEM‐FEM method are conducted. The results indicate that (1) the nonlinear dynamic responses of the HT induced by the physical‐based GM align with the recorded GMs, verifying the practicability of the proposed framework for source‐to‐HT simulation; (2) physical‐based GMs of the hanging wall and foot wall, rupture fault distances and mountain locations can significantly impact the seismic performance of HTs.

Shichun Zhang, Junjun Guo, Wei Liu et al.

Zhigao Yang, Huifang Chen

The Hualien M 7.3 earthquake on April 3, 2024, was a significant and strong earthquake in Taiwan, China in the past two decades. The rupture process of the main shock and strong aftershocks is of great significance to the subsequent seismic activity and seismogenic tectonic research. Based on local strong-motion data, we used the IDS (Iterative Deconvolution and Stacking) method to obtain the rupture process of the mainshock and two strong aftershocks on the 23rd. The rupture of the mainshock was mainly unilateral, lasting 31 ​s, with a maximum slip of 2 ​m, and the depth of the large slip zone is about 41–49 ​km. There is a clear difference between the rupture depth of the main shock and the two strong aftershocks. The depths of the large slip zones of the latter two are 3–9 ​km and 8–10 ​km, respectively. There is also a significant difference in the seismogenic fault between the mainshock and the aftershocks, and we believe that there are two seismogenic fault zones in the study area, the deep and the shallow fault zone. The slip of the deep faults activates the shallow faults.

I. Dijkstra, H. C. Bloomfield, K. M. R. Hunt et al.

<p>Energy systems across the globe are evolving to meet climate mitigation targets. This requires rapid reductions in fossil fuel consumption and significant uptake of renewable generation. Renewable energy sources are weather-dependent, causing production to vary at timescales from minutes to decades ahead. A consequence of this variability is that there will be periods of low renewable energy production, here termed <i>renewable energy droughts</i>. This energy security challenge needs to be addressed to ensure grid stability. India is chosen as a study area as it is a region that has both a large proportion of renewable generation and good subseasonal predictability.</p> <p>In this study, we use synthetic wind and solar photovoltaic production timeseries, previously derived for the Indian energy grid using ERA5 reanalysis from 1979–2022, to identify historical renewable energy droughts. These are defined as periods where wind and solar potential is in the lowest 2.5 % compared to climatology. These events commonly occur from November–February, with the longest historical event being 9 d long.</p> <p>We identify the weather regimes that cause the largest renewable energy droughts over India and investigate potential sources of predictability. Existing large-scale daily weather types and impact-based patterns are used to investigate the different weather patterns causing renewable energy droughts. Renewable energy droughts are caused by low seasonal wind speeds in combination with weather patterns bringing high cloud cover. These are mainly weak northeast monsoon and western disturbances.</p> <p>Sources of potential subseasonal predictability are considered for the largest renewable energy droughts, including the Madden Julian Oscillation and Boreal Summer Intraseasonal Oscillation. Although both have a stronger relationship with high energy potential days, links between phases of these two oscillations and renewable energy drought days are identified. These could help to provide early warnings for challenging security of supply conditions in the future.</p>

Korolev, Yury P., Korolev, Pavel Yu.

The aim of the study was to confirm the possibility of forecasting tsunamis of non-seismic (volcanic) origin using the express method of operational forecasting. The surface wave formed as a result of the explosive volcanic eruption on January 15, 2022 was a superposition of forced (baric) waves caused by an atmospheric pressure wave and free (gravity) waves generated by the disintergration of the disturbance in the source. The express method of operational tsunami forecasting was used to compute the gravitational component of the surface wave. The method allows one to compute the tsunami waveform at any point in the ocean and near the coast in real time based on the data from the sea level measurement stations. The computation of the tsunami on 15.01.2022, its gravitational component, at the DART stations remote from the source was performed based on the data from the DART stations 51425 and 52406 closest to the volcano. For an adequate forecast, the information on the tsunami of the DART stations closest to the source with the duration of a quarter of the first period is sufficient, which is especially important in the operational mode. The result satisfies the definition of the concept of "tsunami forecast" formulated by the Intergovernmental Oceanographic Commission of UNESCO. It has been confirmed that the express method can provide a tsunami forecast regardless of the mechanism of its excitation. It remains unclear how adequate the assessment of the amplitude of surface waves is based on the bottom pressure data is.

Sihai Zhang

Salt halokinesis and the widespread development of salt domes in the southwest of the Arabian Gulf have significantly influenced the regional stress regimes, resulting in diverse and complex fracture patterns, particularly within the tight carbonate reservoirs of the Upper Jurassic (Noufal and Shebl, 2019). These fractures play a critical role in reservoir performance, yet their characterization remains a challenge due to the multi-phase tectonic overprints and the structural complexity introduced by salt-related deformation (Fig. 1). This study aims to investigate the fracture system developed above salt domes under Jurassic rifting, Late Cretaceous transtension, and Tertiary compression. By integrating seismic attributes, borehole imaging logs, and structural evolution analysis, we construct a conceptual fracture model to interpret local fracture patterns and validate them against dynamic data. The results demonstrate that fracture intensity and geometry vary with structural position around the salt dome—major fractures concentrate on the flanks in oval geometries, while crests remain less fractured. Additionally, NW-SE en-echelon fractures from Late Cretaceous transtension dominate areas away from the dome, and their overlap with salt-induced fractures creates highly complex systems in transitional zones. This work provides a practical workflow and geological insights for understanding and predicting fracture development in salt-influenced tight carbonate reservoirs.

Daouda Gaye, Hassan Omer Hassan Mohamed, Sene Serigne Saliou

This study presents a comprehensive analysis of four prominent river-adjacent building projects: Riverside Tower in London, Marina Bay Sands in Singapore, Burj Khalifa in Dubai, and One World Trade Center in New York. By delving into the geological conditions, design strategies, construction hurdles, and performance evaluations of each, the research unravels the complex soil-structure interaction (SSI) challenges these structures faced. Through advanced mathematical models and real-time monitoring, the study demonstrates how innovative engineering solutions, such as piled and raft foundations, waterproofing techniques, and seismic design considerations, were implemented to overcome SSI-induced settlement, flood risks, and dynamic loading impacts. The findings offer invaluable insights and practical guidelines for future river-adjacent building projects, ensuring enhanced structural integrity and long-term performance in such challenging environments.

Zhou Qian, Weixi Kong, J. Cha et al.

The dynamic response of complex soil under earthquake action is a key factor in triggering geological secondary disasters and engineering structural damage. Traditional continuous medium models are limited in the accuracy of disaster risk analysis due to difficulties in characterizing microscopic particle behavior, inefficient parameter calibration, and insufficient dynamic risk assessment. This article constructs a coupled framework of “discrete element simulation machine learning GIS analysis” to achieve cross scale quantification of complex soil seismic response and risk. Establish a particle model with fault and layer characteristics using discrete element method, and capture the evolution of pore water pressure and particle motion by combining fluid structure coupling algorithm; Using LSTM network to invert microscopic parameters (error $\leqslant \text{2. 1 \%}$) and random forest model to predict liquefaction probability (accuracy 91.3%); Integrate multi-source data and generate dynamic risk zoning through GIS (spatial overlap of 88%, response delay $\leqslant 8$ seconds). Experiments have shown that the framework reduces simulation errors by 65% and improves parameter inversion efficiency by 85% compared to traditional methods. It can provide scientific support for seismic design and emergency decision-making in complex geological areas, and is of great significance for enhancing earthquake disaster prevention and control capabilities.

G. W. Shafer, K. Viskupic, A. E. Egger

Individuals with physical disabilities are largely underrepresented in the geoscience workforce. In this study, we analyzed over 2,500 job advertisements (ads) for entry-level geoscience positions across 19 industries to assess how inclusive the United States job market is for people with physical disabilities. We evaluated each ad’s Equal Opportunity Employer (EEO) and accommodation statements to create a measure of geoscience employers’ inclusive practices for people with disabilities. We coded each ad for instances where physical abilities (e.g., traversing rough terrain, driving a vehicle, lifting heavy objects) were listed as required or preferred qualifications and whether these abilities matched the core job function. A significant proportion of job ads (44%) did not include EEO statements, and of those that did, the language used was minimal or abbreviated. Additionally, only 18% of ads mentioned accommodations for people with disabilities. Of the ads that required physical abilities, only 19% requested physical abilities that matched the core job function. Students exploring their career options or applying for entry-level jobs may feel disadvantaged, restrict their applications, or dismiss geoscience careers if they have physical limitations, or if they perceive that the work environment is not inclusive. Overall, online geoscience ads could benefit from adding or modifying equal opportunity employment and accommodations statements to reflect a more inclusive workplace and could explicitly link requested physical abilities to the job description. These results could help employers consider possible modifications to their job advertisements and explore alternative strategies to promote a more inclusive geoscience workforce.

A. D. King, A. D. King, T. Ziehn et al.

<p>Under the Paris Agreement, signatory nations aim to keep global warming well below 2 °C above pre-industrial levels and preferably below 1.5 °C. This implicitly requires achieving net-zero or net-negative greenhouse gas emissions to ensure long-term global temperature stabilisation or reduction. Despite this requirement, there have been few analyses of stabilised climates, and there is a lack of model experiments to address our need for understanding the implications of the Paris Agreement. Here, we describe a new set of experiments using the Australian Community Climate and Earth System Simulator Earth system model (ACCESS-ESM-1.5) that enables the analysis of climate evolution under net-zero emissions, and we present initial results. Seven 1000-year-long simulations were run with global temperatures stabilising at levels in line with the Paris Agreement and at a range of higher global warming levels (GWLs). We provide an overview of the experimental design and use these simulations to demonstrate the consequences of delayed attainment of global net-zero carbon dioxide emissions. We show that there are substantial differences between transient and stabilising climate states and differences in stabilisation between GWLs. As the climate stabilises under net-zero emissions, we identify significant and robust changes in temperature and precipitation patterns including continued Southern Ocean warming and changes in regional precipitation trends. Changes under net-zero emissions differ greatly between regions, including contrasting trajectories of sea ice extent between the Arctic and Antarctic. We also examine the El Niño–Southern Oscillation (ENSO) and find evidence of reduced amplitude and frequency of ENSO events under climate stabilisation relative to projections under transient warming. An analysis at specific GWLs shows that significant regional changes continue for centuries after emission cessation and that these changes are stronger at higher GWLs. Our findings suggest substantial long-term climate changes are possible even under net-zero emission pathways. These simulations are available for use in the community and will hopefully motivate further experiments and analyses based on other Earth system models.</p>

D. T. Robson, D. T. Robson, A. C. W. Baas

<p>In this work, we simulate barchan swarms using the Two-Flank Agent-Based Model and investigate how changes to model parameters and environmental drivers lead to different swarm dynamics. In particular, we explore how the parameter <span class="inline-formula"><i>q</i>_shift</span>, which controls the rate of equilibration between the flanks of an asymmetric dune and thereby the stability of an asymmetric morphology, influences the frequencies of different collision types in the swarm and can be adjusted to produce swarms with dune sizes that are longitudinally homogeneous. Such size stability has been observed in real-world swarms but has not been obtained by previous agent-based models. We also find that, for certain densities of newly added barchans, the dune number density remains constant with downwind distance, something which has also been reported in nature but not in previous agent-based models. We also investigated how boundary condition changes propagate through swarms, something which will become increasingly important in the face of human infrastructure expansion and anthropogenic climate change. Finally, we are able to investigate how asymmetry and spatially patterning in the swarms are influenced by bimodal wind regimes. Since these simulations produce many more realistic phenomena than previous models, this work represents a significant step forward in the our understanding of the interplay between environmental conditions and dune interactions in shaping the dynamics of barchan swarms.</p>

Omid Roozmand, DG Webster, Saeed Abdolhosseini

In this paper, we propose using a mixed genetic-floyd-warshall algorithm in combination with a Floyd-warshall algorithm to model the satisficing behaviour of consumers across spatially differentiated stores. Consumer agents can pick a basket of goods from different stores to either maximize their utility or to “satisfice” by selecting the first basket with a utility that is higher than their satisfaction threshold. The Floyd-warshall algorithm is used to find the shortest path between two chosen stores by considering travel cost. Factors such as price, quality of goods, the cost of travel to the store, consumers' decision-making preferences, and store locations play significant roles in the decision-making process of consumer agents. The model is tested based on mechanisms at the individual level to show how the model works and at the macro-level to reproduce foundational theories in economics.

José Maria dos Santos Rodrigues Neto, Netra Prakash Bhandary, Yuichi Fujita

The rainfall-induced landslide disasters in July 2018 in Southwestern Japan yet again exemplified the severity of slope failure-related damage and the need for improvement of early warning systems. The Japanese Meteorological Agency (JMA) uses a method based on a threshold value of soil water index (SWI), a conceptual measurement that represents saturation of slope soil. The current SWI early warning system uses 60-min rainfall data on a 5-km² mesh and does not take into consideration other landslide conditioning factors such as slope angle and geology. This study calculates SWI values during the July 2018 disasters in Kure City (Hiroshima Prefecture) using 1-min XRAIN rainfall data in a 250-m mesh to investigate the relationship between SWI and landslide occurrence. It was found that the SWI threshold of 124 mm used in the JMA early warning system for the area was surpassed in all cells. A new SWI threshold calculation method taking slope angle and geology into consideration and produced with machine learning is proposed, comprising power lines for different geological units at a two-dimensional graph where points located above the threshold line represent landslide risk. It is judged that this method would provide a more accurate early warning system for landslide disasters.

Yury N. Poltev, Tatyana G. Koreneva, Vsevolod E. Maryzhikhin et al.

The content of Fe, As, Cu, Mn, Cr, Ni, Pb and Cd in the muscles of some aquatic organism species from the Sea of Okhotsk waters of Northeastern Sakhalin was estimated: walleye pollack (Gadus chalcogrammus Pallas, 1814), longhead dab (Limanda proboscidea Gilbert, 1896) and Bering flounder (Hippoglossoides robustus Gill & Townsend, 1897), snow crab (Chionoecetes opilio (O.Fabricius, 1788)). The concentrations of Fe and Cu are reliably higher in the snow crab, in contrast to fish, and Pb concentration is higher in fish relative to the snow crab. There was no difference in the content of trace elements between the flounders and snow crab, and in relation to the walleye pollock, the snow crab has reliably higher concentrations of Fe, Cu, and Hg and lower ones of Pb. The content of Fe is higher in the flounders compared to the walleye pollack. The concentrations of Pb, Cd, As and Hg are safe according to the hygienic requirements for food products and may indirectly indicate a favorable environmental situation in terms of the content of regulated toxic elements in the waters of Northeastern Sakhalin.

W. Fu, W. Fu, L. Tian et al.

<p>Climate change has been proven to be an indisputable fact and to be occurring at a faster rate (compared to the other regions at the same latitude of the world) in boreal forest areas. Climate change has been observed to have a strong influence on forests; however, until now, the amount of quantitative information on the climate drivers that are producing changes in boreal forest has been limited. The objectives of this work were to quantify the spatiotemporal characteristics of boreal forest and forest types and to find the significant climate drivers that are producing changes in boreal forest. The boreal forest in Krasnoyarsk Krai, Siberia, Russia, which lies within the latitude range 51–69<span class="inline-formula">^∘</span> N, was selected as the study area. The distribution of the boreal forest and forest types in the years 1985, 1995, 2005 and 2015 were derived from a series of Landsat data. The spatiotemporal changes in the boreal forest and forest types that occurred over each 10-year period within each 2<span class="inline-formula">^∘</span> latitudinal zone between 51 and 69<span class="inline-formula">^∘</span> N from 1985 to 2015 were then comprehensively analyzed. The results show that the total area of forest increased over the study period and that the increase was fastest in the high-latitude zone between 63 and 69<span class="inline-formula">^∘</span> N. The increases in the areas of broad-leaved and coniferous forests were found to have different characteristics. In the medium-latitude zone between 57 and 63<span class="inline-formula">^∘</span> N in particular, the area of broad-leaved forest grew faster than that of coniferous forest. Finally, the influence of the climate factors of temperature and precipitation on changes in the forests was analyzed. The results indicate that temperature rather than precipitation is the main climate factor that is driving change.</p>

B. Fu, B. Fu, B. Fu et al.

<p>Addressing the sustainability challenges that humanity is facing in the Anthropocene requires the coupling of human and natural systems, rather than their separate treatment. To help understand the dynamics of a coupled human and natural system (CHANS) and support the design of policies and measures that promote sustainability, we propose a conceptual cascade framework of “pattern–process–service–sustainability”, which is characterized by coupling landscape patterns and ecological processes, linking ecological processes to ecosystem services, and promoting social–ecological sustainability. The use of this framework is illustrated by a review of CHANS research experience in China's Loess Plateau (LP), a well-known region for its historically severe soil erosion and successful ecological restoration achieved in recent decades. Ecological restoration in the LP has greatly increased its vegetation coverage and controlled its soil erosion. However, some accompanied issues, like soil drying in some areas due to the introduction of exotic plant species and the mismanagement of planted vegetation and water use conflicts between vegetation and humans caused by the trade-off between carbon sequestration and water supply, have started to threaten the long-term sustainability of the LP. Based on a comprehensive understanding of CHANS dynamics, the social–ecological sustainability of the LP can be improved through enhancing water and food security, implementing basin-wide governance, maintaining ecological restoration achievements, and promoting rural livelihood transition. The research experience accumulated on the LP offers examples of the application of the pattern–process–service–sustainability framework. Future research using this framework should especially focus on the integrated research of multiple processes; the cascades of ecosystem structure, function, services, and human well-being; the feedback mechanisms of human and natural systems; and the data and models for sustainability.</p>

T. Dadayan, E. Dumova-Jovanoska, L. Karapetyan

The main objective of the article is to assess the stress-strain state of building structures under seismic action taking into account the dynamic characteristics of the soils. As well as an assessment of the effectiveness of strengthening method of masonry building based on the Time History Analysis of the bearing capacity of structures. During the study a real existing masonry building is chosen. The building is modeled with the Lira-SAPR computer software with usage of the proposed strengthening method. Then, with the help of full-scale tests, the geophysical characteristics have been determined, as well as the prevailing period of the soil. Based on the existing engineering-geological and obtained by us geophysical data, the synthetic accelerogram corresponding to the masonry building soils have been chosen. The Time History Analysis of the building structures under seismic action have been carried out using previously obtained accelerogram, where the results have been compared with the standard Response Spectral method. And, finally, based on a comparison of various methods for assessing the bearing capacity, the effectiveness of building strengthening has been evaluated. The results of this study can assist the structural engineer in making better decisions for future design decisions.

F. Rashid, D. Hussein, J. Lawrence et al.

Abstract The porosity, permeability, rock material and fracture networks of the newly discovered tight carbonate reservoir rock, the Early Cretaceous Sarmord Formation in Zagros basin are examined. The methods used to investigate the formation are rock cores, micro-resistivity image logs, drill stem tests, drilling fluid data, petrophysical wireline data and drilled cutting samples. The analysed data show that the Sarmord Formation is characterized by extensive open and partially open macro-fractures formed by the local stress from fault and fold propagation. These fractures are sub-vertical with an average dip of 73°, fracture aperture of 0.44 mm and persistence (length) of 11.0 cm. The dominant strike of the fractures is NE-SW, parallel to the observed faults and perpendicular to the main Miran West structure. The vast majority of reservoir porosity was found to be in the rock matrix, with the fractures having very limited impact (average fracture porosity is 0.032%) on porosity. In contrast the fracture permeability averages 240 mD which is four orders of magnitude greater than the matrix permeability. As a result, the inter-connected fractures create effective fluid flow pathways and enhanced hydrocarbon migration perpendicular to the fold structure. Faulting associated with the field structure led to fault damaged zones which act as zones of inter-connected fractures with higher permeability and preferential fluid flow pathways. It is demonstrated that the fracture permeability is driven by the fracture aperture and spacing, whilst the fracture persistence has limited control on permeability. The findings of this study highlight that the importance of fractures and faults on reservoir's quality in tight gas bearing rocks. The network of inter-connected fractures, provide the fluid flow which control the permeability. In contrast the matrix controls the pore spaces and the hydrocarbon storage. This work emphasizes the importance of understanding the impact of structural geology in tight carbonate reservoirs.

Haina Wang, S. Torquato

Time-dependent interphase diffusion processes in multiphase heterogeneous media are ubiquitous phenomena in physics, chemistry and biology. Examples of heterogeneous media include composites, geological media, gels, foams, and cell aggregates. The recently developed concept of spreadability, S(t), provides a direct link between time-dependent diffusive transport and the microstructure of two-phase media across length scales [Torquato, S., Phys. Rev. E., 104 054102 (2021)]. To investigate the capacity of S(t) to probe microstructures of real heterogeneous media, we explicitly compute S(t) for well-known two-dimensional and three-dimensional idealized model structures that span across nonhyperuniform and hyperuniform classes. Among the former class, we study fully penetrable spheres and equilibrium hard spheres, and in the latter class, we examine sphere packings derived from “perfect glasses,” uniformly randomized lattices (URLs), disordered stealthy hyperuniform point processes, and Bravais lattices. Hyperuniform media are characterized by an anomalous suppression of volume fraction fluctuations at large length scales compared to that of any nonhyperuniform medium. We further confirm that the small-, intermediate-, and long-time behaviors of S(t) sensitively capture the small-, intermediate-, and largescale characteristics of the models. In instances in which the spectral density χ̃V(k) has a power-law form B|k|α in the limit |k| → 0, the long-time spreadability provides a simple means to extract the value of the coefficients α and B that is robust against noise in χ̃V(k) at small wave numbers. For typical nonhyperuniform media, the intermediate-time spreadability is slower for models with larger values of the coefficient B = χ̃V(0). Interestingly, the excess spreadability S(∞) − S(t) for URL packings has nearly exponential decay at small to intermediate t, but transforms to a power-law decay at large t, and the time for this transition has a logarithmic divergence in the limit of vanishing lattice perturbation. Our study of the aforementioned models enables us to devise an algorithm that efficiently and accurately extracts largescale behaviors from diffusion data alone. Lessons learned from such analyses of our models are used to determine accurately the large-scale structural characteristics of a sample Fontainebleau sandstone, which we show is nonhyperuniform. Our study demonstrates the practical utility of the diffusion spreadability to extract crucial microstructural information from real data across length scales and provides a basis for the inverse design of materials with desirable time-dependent diffusion properties.