High Seismic Activity Research Articles

Evaluation of Disaster Risk and Mitigation Strategies for Post-Disaster Permanent Housing in the Palu Koro Fault Area

The Palu Koro Fault in Sulawesi, Indonesia, an area with very high seismic activity, with a historical record of large earthquakes, including the devastating event on September 28, 2018. This earthquake, accompanied by a tsunami and liquefaction, caused significant damage to infrastructure and residential areas in Palu City, Donggala Regency, and Sigi Regency. A future similar event needs to be studied based on technical aspects related to disaster vulnerability criteria. The SNI 03-1733 (2004) establishes the disaster risk criteria in residential areas, such as landslides, floods, and earthquakes. BNPB has also created a disaster-prone map in Indonesia. However, studies on safe housing emerging from various disasters, such as earthquakes, tsunamis, liquefaction, and other risks, specifically being in the path of planes or near high voltage currents, are still limited. This research aims to assess disaster risk in post-disaster permanent residential relocation using the AS/NZS ISO 31000 risk management framework, which includes vulnerability conditions, evaluation of technical aspects, disaster risk analysis, and development of recommendations, combining quantitative and qualitative approaches. Data were analyzed using a scale-based method, with descriptive statistics to calculate frequency, averages, and percentage of the risk categories at each location. Qualitative analysis produces narratives regarding the impact of risks on community safety and residential infrastructure. The current study results show that high-risk factors, including earthquakes, floods, and landslides, require immediate mitigation. Additionally, immediate action should be taken for risks categorized as unacceptable, involving building strengthening, drainage system improvement, and soil stabilization, to reduce the risk of liquefaction. Concerning moderate risks, which belong to the undesirable category, they also require further treatment to minimize the impact of future disasters. The current study also emphasizes the importance of community survivors' participation in the relocation and disaster preparation process. This underlines the need for an integrated approach to disaster risk management to strengthen the resilience of communities and infrastructure in disaster-prone areas.

Radial Anisotropy of the Crust and Uppermost Mantle Beneath the Central North China Craton From Joint Inversion of Surface Wave Dispersion Curves and Ellipticity: Implications for the Mechanisms of Differential Rifting and Uplift

AbstractThe central North China Craton (NCC) acts as a transition zone between the stable western and reworked eastern NCC. It is characterized by high seismic activity and experienced volcanic activity with small magma volumes. To assess the dynamic processes of the central NCC, particularly in a zone marked by intense differential tectonic deformation, we have obtained a 3‐D radial anisotropic model of crust and uppermost mantle via joint inversion of Love‐ and Rayleigh‐wave dispersion curves and ellipticity measurements. Compared to models without Rayleigh‐wave ellipticity, our new model shows improved accuracy in crustal radial anisotropy. This refined model reveals two noteworthy geological features: (a) Most of the Shanxi Rift has pronounced positive radial anisotropy in the crust except for Linfen and Xinding Basins, as critical earthquake‐prone areas, which are characterized by weak positive to negative anisotropy with much thinner sediments. This observation suggests that differential rifting processes with uneven sedimentation and crustal deformation occur in these Cenozoic basins due to right‐lateral strike slip motion. (b) The crust in the Lvliang Mountains shows weak positive or negative anisotropy with a lower crustal low‐velocity layer beneath the northern parts, whereas the crust in the Taihang Mountains exhibits positive anisotropy. This implies that the Lvliang Mountains experienced uplift under compressional environments since the Yanshanion Orogeny. Furthermore, the magmatic underplating in the crust accelerated the uplift of the northern Lvliang Mountains. In contrast, the Taihang Mountains underwent relative uplift under extensional environments, along with the subsidence of the Bohai Bay Basin during the Cenozoic.

Seismic Risk Assessment for the City of Sofia, Bulgaria

An earthquake is the most destructive natural phenomenon, with its sudden onset and rapid spread impacting large areas. Among the various geohazards, seismic ones dominate in terms of their social and economic effects on human life and the urban environment. In the present study, a deterministic earthquake ground motion scenario for the city of Sofia (the capital of Bulgaria) is presented. The earthquake risk posed to Sofia is quantified by considering the city’s seismic context, which contributes to its hazard and risk. The assessment of seismic hazards and the generation of earthquake scenarios make up the first step of seismic risk evaluations, as risk reduction strategies can only be developed with a better understanding of these threats. Risk assessment and its associated management comprise the most effective approach to estimating the impact of seismic hazards on the city of Sofia, which exhibits high seismic activity. Our findings provide a basis for local governments to review their susceptibility and preparedness. The consideration of earthquake scenarios in the creation of policies for seismic risk reduction will allow us to focus on the prevention of earthquake effects rather than on the activities following these disasters.

A Roman bath with broken windows in Asine, Argolis. The result of repeated earthquakes?

A substantial assemblage of Roman window glass—consisting primarily of “cast”, matt/glossy examples, but also including cylinderblown, double-glossy window glass—was discovered during the 1926 excavations of a Late Roman bath in Asine, Argolis, the Peloponnese, Greece. It is clear that this material emanates from damage done to the building, and the question of whether this had human or natural causes is discussed in this paper: was it the “barbarian” invasion of the Visigoth king Alaric in the late 4th century AD that led to the windows being broken? Or, was the damage caused by the earthquakes known to have hit the Eastern Mediterranean area in Late Antiquity? Traces of destruction typical of earthquakes were found in the bath building, and the destruction occurred in a period known for its high seismic activity: the so-called Early Byzantine Tectonic Paroxysm, which led to the conclusion that the bath was hit by at least one, possibly several, earthquakes, causing the windows to shatter and fall out of their frames. Some of the glass sherds were in all probability hidden under dust and debris and were never recovered despite the fact that glass was extensively recycled at the time.

Analysis of Vibrational Characteristics of the Bank of China Tower in Hong Kong with ANSYS

Abstract. With the rapid urbanization and technological advancements in construction, modern high-rise buildings have become a symbol of urban development. However, these structures face unprecedented challenges due to their increasing height and the complex dynamic loads they must withstand. This paper presents a comprehensive analysis of the Bank of China Tower in Hong Kong, a prominent architectural landmark, using ANSYS software to perform modal and transient structural analyses. The primary structure of the tower consists of five steel-reinforced concrete columns, designed to resist dynamic responses under extreme conditions such as high wind speeds and seismic activities. The modal analysis identified multiple natural frequencies and vibration modes, providing insights into the dynamic behavior of the structure. The transient structural analysis, conducted under seismic wave loading, demonstrated the tower's admirable performance under specified seismic conditions, highlighting its sufficient safety margins. This study emphasizes the importance of advanced materials and innovative structural designs in ensuring the stability and safety of high-rise buildings. The findings contribute significantly to the field of structural engineering, offering valuable insights for the design and analysis of future high-rise structures.

Present-day incipient fault coalescence at a relay zone (Jiloca extensional basin, Spain): Evidence from instrumental seismicity

The relay zones between NW-SE to NNW-SSE striking faults of the Jiloca graben (Iberian Chain) mostly show distributed along-strike fault and fracture patterns. The latter are chiefly controlled by the Late Pliocene-Quaternary regional stress field, and secondarily respond to local controls from inherited structures. Such fracture patterns contrast with the classical models of transverse connecting faults controlled by relay kinematics. North of the Concud fault trace, at the relay zone with the Sierra Palomera fault, an unusually high seismic activity has been noticed since 2014, with magnitudes up to M = 3.5. Upgrading of the National Seismic Network allowed obtaining such new detailed records, while the installation of a new seismometer by the IGN within the study area has improved the reliability of focal depth data since 2017. A high-precision absolute relocation of seismicity from 01/01/2000 to 30/05/2022 has been carried out. The results show that (i) the epicentres are significantly clustered along a nearly N-S trending band, and (ii) the focal depths range from 0 to 14 km, in good agreement with the thickness of the brittle crust. This 3D spatial distribution of seismicity is interpreted as a consequence of activation of either a single fault or a fault zone, nearly vertical and N-S striking. Such structural setting is consistent with the surficial fracture patterns observed at both map and outcrop scale: NNW-SSE and NNE-SSW oriented faults and fractures, orthogonal to the ENE-WSW to ESE-WNW regional σ3 trajectories, together with NW-SE trending ones controlled by inherited contractive faults. The present-day seismic activity suggests that along-strike, incipient fault propagation at the relay zone between the Concud and Sierra Palomera faults is currently operating under the control of the remote stress field.

Optimizing steel plate shear wall performance: influence of infill plate thickness and connection length to vertical boundary elements

The Steel Plate Shear Wall (SPSW) is widely used as a lateral force resisting system in areas prone to high seismic activity. This is because of its exceptional ductility and ability to dissipate energy. Previous studies have indicated that disconnecting the infill plate from the Vertical Boundary Element (VBE) can decrease the demands on the column. The observed outcomes lead to a decline in both the energy dissipation capability and the lateral load-bearing capacity. The primary goal of this investigation is to mitigate stress on the column while concurrently reducing both the energy dissipation and lateral force capacities. To accomplish this, a partial connection will be established between the infill plate and the Vertical Boundary Element. Thus, the overarching objective of this research is to identify the optimal connection length that minimizes the demands on the column while simultaneously curtailing the reduction in energy dissipation and lateral force capacities. Using Abaqus software, twenty models with different infill plate thicknesses and lengths of connection between the infill plate and Vertical Boundary Element were analysed. To determine the optimal length of connection between the infill plate and Vertical Boundary Element, the energy dissipation capacity, lateral load capacity, and column stresses were evaluated and compared. The maximum dissipation of energy occurs at a connection length of 75% between the infill plate and Vertical Boundary Element and an infill plate thickness of 12 mm. In contrast, the greatest lateral load capacity is achieved at connection lengths of 50% between a 25 mm infill plate thickness and a Vertical Boundary Element weight of 25%. The column stress reaches its minimum value when the infill plate measures 20 and 25 mm, and it reaches its maximum value when the infill plate measures 6 mm and 12 mm. By increasing the thickness of the infill plate and minimizing its connection to the Vertical Boundary Elements, the column stress in Vertical Boundary Elements can be decreased, while simultaneously enhancing lateral load capacity and maintaining an adequate level of energy dissipation.

SEISMIC VULNERABILITY ASSESSMENT OF AN HISTORICAL UNREINFORCED MASONRY BUILDING OF THE XIXTH CENTURY: EL FETH HIGH SCHOOL IN BLIDA, ALGERIA

Schools In Algeria, built in the XIXth and XXth centuries, are not only places of education and learning, but make up a rich cultural heritage of architectural techniques and traditional know-how. However, their seismic vulnerability risks the safety of their occupants. They were built of masonry before seismic regulations were put into place, which increases their sensitivity to seismic hazard. Algeria is situated in a well-known zone of high seismic activity and the risk to these buildings challenges their structural behaviour. This study focuses on an assessment of seismic vulnerability on a specimen built entirely in hollow brick which wonderfully represents this architectural heritage leading to a better understanding of the potential risks for these buildings, at a structural level. Macro element models, using the Tremuri software, are subjected to a non-linear “Pushover” analysis in order to determine the degree of vulnerability and locate the weak sections of the structure which could collapse during seismic action. This study aims to highlight the seismic risks of these types of structures and also offer appropriate guidelines and recommendations that could be of use during a possible rehabilitation or conservation program of this built heritage site.

Shaking-table tests and numerical simulations study of subway stations in loess region

The loess region in China, known for its high seismic activity and the extreme vulnerability of loess to earthquakes, presents a considerable threat to the seismic safety of underground structures, including subway stations. With the Xi'an Aerospace City subway station as the background, a subway station model was designed, and shaking table tests were conducted under various conditions to analyze the seismic damage and dynamic responses in this study. The study reveals the seismic vulnerable areas and dynamic response patterns of the subway station under different spectral earthquake actions. Simultaneously, a three-dimensional numerical modeling analysis accounting for soil-structure interaction, was conducted to explore the displacement response of the structure and soil. Results indicate a noticeable amplification effect on the acceleration of both the structure and the soil under seismic motion. The structure exhibits a suppressive effect on the acceleration amplification of the surrounding soil, diminishing with increasing seismic motion intensity. Different depths show varying differences in acceleration responses between the structure and adjacent soil. Structural strain responses and damage phenomena suggest that the central column is the seismic vulnerable area of the subway station. Additionally, the strain distribution of the structure exhibits a distinct spatial effect. The relative horizontal displacement between the structure and the soil follows certain patterns in the depth direction, with the structure experiencing smaller relative horizontal displacement than the soil under seismic action due to the constraining effect of surrounding soil on its displacement response. The experimental conclusions provide valuable reference points for the seismic design and analysis of subway station structures in loess regions.

Evaluation of priority index for enhancing the seismic resilience of tunnels

Tunnels are essential infrastructure elements, offering significant economic, social, and environmental benefits. However, they are particularly vulnerable to seismic risks, especially in regions with high seismic activity. Given their importance in terms of safety, economy, and social factors, it is crucial for the relevant authorities to prepare for natural and human-made disasters by enhancing the seismic resilience of tunnels. In Algeria, where the number of tunnels is high, this necessity is particularly urgent.This article proposes a prioritization model aimed at improving the seismic resilience of tunnels, based on the expertise of specialists and structured into three main steps. The first step involves identifying key criteria, including the tunnel's condition, design phase, availability of alternative routes, social importance, geometric shape, and seismic zone. The second step applies the Analytic Hierarchy Process (AHP) to calculate the weights of the criteria and incorporates expert opinions through the Euclidean Distance-Based Aggregation Method (EDBAM). Finally, the third step establishes the Priority Index for Tunnel Seismic Resilience Improvement (PIT).The model was tested on five tunnels, and the classification obtained based on the priority index was found to be well aligned with the observed reality on the ground.

Multi-hazard assessment for flood and Landslide risk in Kalimantan and Sumatra: Implications for Nusantara, Indonesia's new capital

Situated within the Ring of Fire and characterized by a tropical climate and high seismic activity, Indonesia is uniquely vulnerable to natural disasters such as floods and landslides. These events pose significant threats to both the population and infrastructure. This study predicts areas exposed to flood and landslide risk by considering various environmental factors related to climate, topography, and land use. The predictive performance of three machine learning models—naïve Bayes, k-nearest neighbors, and random forest (RF)—was evaluated by comparing the AUC, RMSE, and R2 values of each model. Ultimately, the RF model, which demonstrated the highest accuracy, was used to prioritize disaster impact factors and generate hazard maps. The results identified the interaction of rainfall, land use, and slope aspect as the most critical determinants of hazard occurrence. The predicted hazard maps revealed that approximately 26.7 % of the study area was vulnerable to either floods or landslides, with 16.8 % of the area experiencing both. The new capital of Nusantara showed a relatively higher multi-hazard risk than did the overall study area and protected zones, with 22.1 % of the hazard area vulnerable to both flooding and landslides. In single hazard zones, areas classified as at risk for floods had a higher mean probability of experiencing both hazards (43 %), as compared to areas classified as at risk for landslides (22 %). As a result, urban planners and relevant stakeholders can now utilize the hazard maps developed in this study to prioritize infrastructure reinforcement and disaster risk areas, integrating land use planning with risk assessment to mitigate the impact of disasters. By employing these strategies, Indonesia and other countries facing similar challenges can now enhance their disaster preparedness and response capabilities in new capital regions and other areas, ultimately planning for more sustainable urban development.

Seismic Vulnerability Assessment of Non-Overflow Concrete Gravity Dam Section

Abstract As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has emerged as a crucial strategy for addressing the energy crisis. To promote hydropower development, numerous tall concrete dams are either under construction or in the planning stages. These dams are frequently situated in areas with elevated water levels and face the challenge of being located in regions with high seismic intensity. An accident resulting from the failure of concrete dams can pose significant threats to both economic development and public safety. Therefore, it is of crucial importance to investigate the stability of such dams, particularly under conditions of high water levels and seismic activity. The finite element program Geostudio is being undertaken to evaluate a complete numerical analysis of the dam. In this paper, Longtan Dam has been selected as the case study for the research. This study is applied in two cases: seismic and static conditions. A two-dimensional seismic numerical analysis was carried out using the Koyna earthquake acceleration time records in 1976. The results of the FEM model concluded that the dam is unsafe under sesmic conditions. The concrete-rock interface, particularly susceptible to sliding, was identified as the most critical part of the dam, presenting the most likely failure mode. The study highlights the significance of its methodology in investigating earthquake effects on dams, prioritizing it over the achieved results. The aim is for the conclusions and recommendations to provide valuable guidance for future studies and initiatives focused on enhancing safety at hydropower dams.

Investigation of RC structure damages after February 6, 2023, Kahramanmaraş earthquake in the Hatay region

From a tectonic perspective, Türkiye is a geographical region known for its high seismic activity, with some of the most active faults in the world. On February 6, 2023, two consecutive earthquakes with magnitudes of Mw 7.7 and Mw 7.6 struck Kahramanmaraş within a remarkably short time span of 9 h. This event stands out as a rare and unprecedented tectonic occurrence in terms of seismicity and tectonic activity over the past 100 years. The impact of these two major earthquakes on the region's reinforced concrete structures was significant, resulting in severe damage and the collapse of numerous buildings. It is of utmost importance to investigate and examine the design flaws and underlying factors that contributed to the damage observed in the reinforced concrete structures affected by these earthquakes. Such research will not only contribute to the improvement of structural design, seismic regulations, and quality control measures during construction but also enhance our understanding of earthquake engineering. In this study, an in-depth field investigation was conducted on reinforced concrete structures in Hatay, one of the regions most affected by the Kahramanmaraş earthquakes. The damages occurring in the buildings were documented through a detailed field survey and analyzed. A total of 540 reinforced concrete structures in the Hatay region were extensively examined, and the damages that occurred in these structures were photographed and interpreted to understand their underlying causes. Subsequently, based on the findings from the field investigation, a structural model was designed that incorporated the most significant design and construction errors responsible for the damages observed in the 540 examined structures. The devised model was subjected to static push-over analysis and nonlinear dynamic analysis using the SAP2000 finite element software, and the results obtained were interpreted.

Evaluating the response modification factor (R) for reinforced concrete and steel structures equipped with TADAS devices designed for high seismic hazard in Colombia

Colombia is a country with high seismic activity due to its location at the convergence of the Nazca and South American tectonic plates, making structural safety a key priority in the design, construction, and retrofit of buildings. Currently, one of the most used seismic resistance systems are moment-resisting frames, due to their easy construction and good behavior under vertical loads, however, they are susceptible to structural damage when subjected to moderate to high-intensity earthquakes, which makes the use of seismic protection systems an adequate alternative to prevent damage during seismic events. The Colombian seismic design code NSR-10 proposes a design methodology using a linear structure that represents a non-linear behavior of the building when the expected design earthquake occurs through the response modification factor R. However, the NSR-10 seismic design code does not contemplate the response modification factor for structures with seismic protection systems. Therefore, in this research, a design procedure was configured for buildings with moment-resisting frames of reinforced concrete and steel equipped with TADAS (triangular-plate added damping and stiffness) dampers. The procedure evaluated the developed response modification factor of structures located in high seismic hazard areas in Colombia and considered regular buildings with varying numbers of stories and special energy dissipation capacity. The capacity of the structures was evaluated through nonlinear static analysis using the Pushover method in SAP2000 software. Finally, the response modification factors were calculated for regular buildings with moment-resisting frames and different numbers of stories.

Integrated study on buried pipelines, co-seismic landslides, and magnitude conversion for 2023 Türkiye earthquake

Türkiye is known for its intricate tectonic structure and high seismic activity, which makes in-depth research on earthquakes necessary. This research paper presents a multifaceted examination of earthquake impact in Türkiye, encompassing critical elements of seismic vulnerability with a special focus on the latest twin earthquake of February 6, 2023. Firstly, a three-dimensional finite element (FE) analysis has been conducted to explore the buried pipeline behavior under left-lateral strike-slip faults. Secondly, making use of the earthquake data from 1976 to 2023, a new Newmark displacement-based model has been proposed which predicts co-seismic landslide displacement. Finally, new magnitude conversion relations are developed in the generalized moment magnitude scale (Mwg) for Türkiye using three statistical regression techniques. The maximum tensile strain was found to be around 2.0% based on the findings of the 3D numerical study of an underground pipe that was subjected to left-lateral strike-slip fault movement. The proposed co-seismic landslide displacement model was developed based on moment magnitude, yield acceleration, and peak ground acceleration, which yields an R-squared value of 0.93. Outcomes of the magnitude conversion study depicted that the improved general orthogonal regression (IGOR) relationships developed in this study performed better than the other conventional methods of regression. Also, the proposed regional relations based on Mwg scale perform better than global relations as they provide closer values to the observed ones. By offering a comprehensive perspective on seismic impact, the research lays the groundwork for upgraded predictive methods and refined seismic design considerations. The proposed models and conversion relations contribute to the strengthening of critical infrastructures, providing a forward-looking approach to enhance preparedness and resilience against earthquake disasters in Türkiye.

Quantifying the features of earthquake clusters in north-Central Iran, based on nearest-neighbor distances and network analysis

The statistical features of earthquake clusters in North-Central Iran (Tehran Region) are investigated, with the aim of quantitatively characterizing the properties of earthquake triggering and allow exploring their possible relations with the tectonic setting of the study area.The nearest-neighbor approach is used for the identification of the earthquake clusters in the space-time-energy domain. This approach permits for a data-driven identification of clusters so that, within multi-event clusters, the features of secondary and higher orders dependent events can be explored. The study is based on a revised dataset that is extracted from the catalog compiled by the Iranian Seismological Center (IRSC) for the period of 1996–2022. In order to exclude the effect of non-tectonic events, which turn out quite numerous within the study region, explosions within quarry-rich areas are removed; the identification of non-tectonic events is performed by considering the normalized ratios of daytime to nighttime events in an iterative removal procedure. According to preliminary analysis of the resulting catalog, an area is selected, within which a satisfactory completeness level is assessed for events with magnitude >2.0. Robust values of the scaling parameters, namely the b-value and the fractal dimension of epicenters, are also computed and are used to calculate the nearest-neighbor distances and to identify the earthquake clusters.The nearest-neighbor method also permits to investigate the internal structure of earthquake sequences, and to differentiate the spatial properties of seismicity according to the different topological features of the clusters structure. The obtained results allow us identifying two macro-areas, approximately separated by the 52°E meridian, which are characterized by different clustering features, namely: high complexity indexes, indicating simple (burst-like) structure of clusters, to the East; low complexity index, corresponding to complex multi-level (swarm-like) structure of clusters, to the West. The complexity measures, borrowed from network theory (i.e. the Closeness and Outdegree Centralization indexes), consistently capture the complexity of the identified clusters, and confirm that the cluster structures have distinct preferred geographic locations. The territorial heterogeneity of the examined clustering properties can be related with the spatial variability of tectonic, structural and geophysical features of the Alborz region, in good agreement with findings from the Alps-Dinarides junction (Northeastern Italy), a region also characterized by a contractional structural setting, mainly including reverse and strike-slip faulting systems, and by moderate to high seismic activity.

Damage State of Non-Engineered Residential Buildings Owing to Earthquakes: A Case Study in Pacitan Regency, Indonesia

Abstract The Pacitan Regency of Indonesia is located in an area of high seismic activities. Regrettably, field surveys held in Pacitan Regency, Indonesia have revealed the prevalence of low-income housing structures that do not meet the engineering standards and are vulnerable to damage during earthquakes. The seismic evaluation of these buildings is urgently required. This study proposes realistic damage state limit values for the seismic damage evaluation of non-engineered buildings. For this purpose, an incremental dynamic analysis was conducted on a sample of non-engineered buildings in Pacitan to evaluate their probable seismic damage. As a result, curves showing the dynamic pushover responses of buildings to various input earthquakes were plotted. These curves were then summarized as three-linear curves, providing a single value for the average response of the structure. Based on this simplified curve, a more realistic damage-state limit for non-engineered structures are proposed. The damage levels of slight (DS1), moderate (DS2), extensive (DS3), and complete (DS4) were determined using the drift ratio at the linear elastic limit, midway point between the linear elastic and yield limits, yield state, and 80% rupture limit, respectively.

Household preparedness for multi-natural hazards in coastal communities

Natural hazards have generated significant human and economic losses throughout history. This issue concerns the Pacific Ring of Fire (PRF) coastal cities. Chile is located on the PRF and is one of the countries with the highest seismic activity in the world. Consequently, this has resulted in a high seismic culture among the inhabitants but less knowledge and awareness of other threats, such as hydrometeorological events. Therefore, this study assessed household preparedness for multiple natural hazards in two coastal cities in Chile.To achieve this goal, we used the results of a survey conducted on a statistically representative sample of two of the main coastal cities in Chile: Valparaíso (n = 548) and Concepción (n = 585). The survey assessed household preparedness, participation in preparedness activities, and sociodemographic variables.The results showed that regardless of the study area, people perceive they are more prepared for earthquakes/tsunamis than fires and floods. Inhabitants from both cities rarely participate in preparedness activities, evidencing the importance of encouraging community members to become involved in activities to learn skills and strategies to cope with multiple hazards. Finally, the results show significant differences in preparedness based on sociodemographic characteristics; middle-aged adults declare participating more in disaster-related activities and being more prepared at home against earthquakes, tsunamis, and fires. The implications of these findings to prepare communities are discussed.

Seismic Domain Identification Algorithm Using Fuzzy Logic Methods With Combined Geological and Geomorphological Data for the Case of Sakhalin Island

An algorithm for identifying seismic generation zones or “seismic domains” using fuzzy logic has been developed and tested on the island of Sakhalin. Initial data were obtained from diagrams of the distribution of “weak” zones, relief elevation distribution skewness, and magnitude of recent area deformation for one year. These data were processed using a γ-operator in fuzzy logic with γ = 0.9, which allowed us to identify areas with high seismic activity. The areas where these active areas intersect with zones with increased compressive stress values, as determined by computer modeling, were considered to be seismic zones. It was shown that, if there are not enough source materials available, it is possible to exclude information about the recent deformation field from consideration and use an assumed grid of active faults for computer modeling. This approach may be useful when analyzing areas that have not been studied well.

Performance of Engineered Cementitious Composites (ECC) in shield tunnel segmental joints: A comparative study with ordinary reinforced concrete

Shield tunnel segmental joints are traditionally vulnerable, limited by their tensile capacity and susceptibility to cracking. Engineered Cementitious Composites (ECC) offer a promising solution due to their superior tensile strength, exceptional crack resistance, and remarkable toughness. However, the application of ECC in tunnel segment joints remains unexplored. To address this gap, this paper conducted comprehensive full-scale tests of ECC segmental joints versus ordinary reinforced concrete (RC) segmental joints. It investigated mechanical responses including material behavior, deflection, joint action, bolt strain, crack development, and failure modes. Results revealed that: (1) ECC joints provided a 33.97 % higher stable bearing capacity and a 50 % increase in initial cracking strength compared to RC joints. (2) ECC joints excelled in crack control, maintaining crack widths below 0.2 mm, while RC joints experienced significant cracking with widths exceeding 1 mm. (3) In terms of toughness, ECC joints surpassed RC by 66 % in the elastic stage and 123 % in the normal serviceability stage, with 96 % higher ductility. (4) ECC joints significantly outperformed RC joints in bolt stress uniformity and concentration, achieving a 43.21 % reduction in average bolt stress. (5) Regarding multi-scale mechanical effects, ECC joints increased the toughness and strength advantage over RC by more than 45 % in the elastic phase. These results reveal the potential of ECC in significantly enhancing the durability and resilience of shield tunnels, particularly in harsh environments subjected to high ground stress or seismic activities.