Search Results (145)

This study examines urban expansion, coastal erosion, and extreme wave events in Licantén, Maule Region, following the 2010 earthquake and tsunami. Using multi-source data—Landsat and Sentinel-2 imagery, ERA5 reanalysis, high-resolution Maxar images, UAV surveys, and the CoastSat algorithm—we detected significant urban growth in tsunami-prone areas: Iloca (36.88%), La Pesca (33.34%), and Pichibudi (20.78%). A 39-year shoreline reconstruction (1985–2024) revealed notable changes in erosion rates and shoreline dynamics using DSAS v6.0, influenced by tides, storm surges, and wave action modeled in R to quantify storm surge events over time. Results underscore the lack of urban planning in hazard-exposed areas and the urgent need for resilient coastal management under climate change. Full article

The analysis of the vulnerability of vernacular buildings to climatic hazards is nowadays a subject of significant importance due to the consequences of climate change. This study assesses the vulnerability of vernacular buildings to three climatic hazards (heavy rains, strong winds and high heat) in the Kara region to identify the vulnerable parts of these constructions that require reinforcement. It is based on PTVA (Papathoma Tsunami Vulnerability Assessment), a multi-hazard analysis methodology, which uses vulnerability indicators. It focuses on the Kabiyè and Nawdeba peoples, who are the major ethnic groups in the region. Focus groups with the population, interviews with professionals and a series of surveys of 125 households in the visited territories enabled us to identify, firstly, the types of vernacular constructions in the region, the climatic hazards that occur there and the indicators that affect the vulnerability of the constructions. Secondly, we calculated the vulnerability index for each type of construction to the three climatic hazards. The vulnerability index of Kabiyè vernacular architecture (KVA) to heavy rain, high heat and strong wind is 0.379, 0.403 and 0.356, respectively. The Nawdéba vernacular architecture (NVA) vulnerability score is 0.359 for heavy rain, 0.375 for high heat, and 0.316 for strong wind. The index of vulnerability to heavy rain, high heat and strong wind for contemporary architecture (CA), as we term the current state of evolution of these two forms of architecture, is 0.499, 0.522 and 0.456, respectively. This study reveals that contemporary architecture (CA) in the Kara region, regardless of the type of hazard considered, is the most vulnerable construction model in the region. It also highlights the indicators that accentuate the vulnerability of vernacular constructions. Regardless of the type of construction, special attention must be paid to features such as roof style (roof slope, shape and material) and building style (form and state of maintenance of the building) to increase the resilience of buildings to climatic hazards. Full article

High-resolution seismic reflection profiles from the offshore segment of the Littoral Fault Zone (LFZ) near Nan’ao Island were analyzed to investigate fault activity and its potential link to the 1918 M7.3 earthquake. The data reveal a ~19 km-wide graben bounded by seaward- and landward-dipping normal faults, with fault-propagation folds and growth faults reaching the seafloor. Forward modeling of the fault-propagation fold indicates three discrete episodes of normal dip-slip displacement (~20 m per phase), separated by prolonged quiescent periods, suggesting episodic fault activity and seismic-scale strain accumulation. Despite the regional NW–SE compressional stress regime, active normal faulting is observed, implying vertical stress as the dominant driving force. A gravitational seismic model driven by upper crustal loading is proposed to explain both the fault motion and the down-draw tsunami observed during the 1918 event. These findings offer new insights into intraplate seismogenic mechanisms and associated hazards along the South China coast. Full article

Traditional tsunami vulnerability assessments often rely on empirical models and field surveys, which can be time-consuming and have limited accuracy. In this study, we propose a novel approach that integrates high-resolution Unmanned Aerial Vehicle (UAV) photogrammetry with numerical simulation to improve vulnerability assessment efficacy in Ancon Bay, Lima, Peru, by using the Papathoma Tsunami Vulnerability Assessment (PTVA-4) model. For this purpose, a detailed 3D representation of the study area was generated using UAV-based oblique photogrammetry, enabling the extraction of building attributes. Additionally, a high-resolution numerical tsunami simulation was conducted using the TUNAMI-N2 model for a potential worst-case scenario that may affect the Central Peru subduction zone, incorporating topographic and land-use data obtained with UAV-based nadir photogrammetry. The results indicate that the northern region of Ancon Bay exhibits higher relative vulnerability levels due to greater inundation depths and more tsunami-prone building attributes. UAV-based assessments provide a rapid and detailed method for evaluating building vulnerability. These findings indicate that the proposed methodology is a valuable tool for supporting coastal risk planning and disaster preparedness in tsunami-prone areas. Full article

The Pacitan Regency is at risk of megathrust earthquakes and tsunamis due to the seismic gap along the southern region of Java Island, making risk-reduction efforts crucial. This research aims to analyse the tsunami risk associated with a potential megathrust earthquake scenario in Pacitan’s coastal areas and develop sustainable mitigation strategies. The research employs spatial analysis to evaluate the risk and subsequently formulate strategies for long-term mitigation. A weighted overlay method was utilised to integrate hazard (H) and vulnerability (V) datasets to produce a tsunami risk map (R). The hazard component was modelled using a tsunami propagation simulation based on the Shallow Water Equations in the Delft3D-Flow software, incorporating an earthquake scenario of Mw 8.8 and H-loss calculations in ArcGIS Pro 10.3. The vulnerability assessment was conducted by overlaying population density, land use, and building footprint from the Global Human Settlement Layer (GHSL) datasets. Finally, sustainable strategies were proposed to mitigate the tsunami risk effectively. The results show that Pacitan faces significant tsunami disaster risk, with tsunami waves at the coast reaching 16.6 m. Because the coast of Pacitan is densely populated, mitigation strategies are necessary, and in the present contribution, the authors developed holistic spatial planning, which prioritise the preservation and restoration of natural barriers, such as mangroves and coastal forests. Full article

The generation of an earthquake and a tsunami is a coupled process of radiating seismic waves and exciting tsunamis, and the two types of waves are simultaneously recorded by ocean-bottom pressure sensors. In order to constrain the earthquake source and evaluate the tsunami hazards, it is necessary to separate the tsunami waves. It is traditional to apply a low-pass filter such that the seismic waves are filtered and the tsunami waves remain. However, filtering may also cause distortion of the tsunami waves. In this study, we first use the finite-element method to simulate the generation of seismic and tsunami waves and show that the coupling is a linear superposition of the two waves. We then propose a new method to extract the tsunami waves. First, a low-pass filter with relatively high cutoff frequency that does not affect the tsunami waves is adopted, so that only tsunami waves and low-frequency seismic waves remain. The low-frequency seismic waves satisfy a theoretical equation $p=\rho ha$ (p pressure, $\rho$ water density, h water depth, and a seafloor vertical acceleration), and they can be predicted and removed by utilizing the records of ocean-bottom acceleration. We demonstrate the procedure by numerical simulations and show that the method successfully extracts clean tsunami signals, which is important for earthquake source characterization and tsunami hazard assessment. Full article

The 2018 Sulawesi Earthquake and Tsunami serves as a backdrop for this work, which employs simple and straightforward remote sensing techniques to determine the extent of the destruction and indirectly evaluate the region’s vulnerability to such catastrophic events. Documenting damage from tsunamis is only meaningful shortly after the disaster has occurred because governmental agencies clean up debris and start the recovery process within a few hours after the destruction has occurred, deeming impact estimates unreliable. Sentinel-2 and Maxar WorldView-3 satellite images were used to calculate well-known environmental indices to delineate the tsunami-affected areas in Palu, Indonesia. The use of NDVI, NDSI, and NDWI indices has allowed for a quantifiable measure of the changes in vegetation, soil moisture, and water bodies, providing a clear demarcation of the tsunami’s impact on land cover. The final tsunami inundation map indicates that the areas most affected by the tsunami are found in the urban center, low-lying regions, and along the coast. This work charts the aftermath of one of Indonesia’s recent tsunamis but may also lay the groundwork for an easy, handy, and low-cost approach to quickly identify tsunami-affected zones. While previous studies have used high-resolution remote sensing methods such as LiDAR or SAR, our study emphasizes accessibility and simplicity, making it more feasible for resource-constrained regions or rapid disaster response. The scientific novelty lies in the integration of widely used environmental indices (dNDVI, dNDWI, and dNDSI) with threshold-based Decision Tree classification to delineate tsunami-affected areas. Unlike many studies that rely on advanced or proprietary tools, we demonstrate that comparable results can be achieved with cost-effective open-source data and straightforward methodologies. Additionally, we address the challenge of differentiating tsunami impacts from other phenomena (et, liquefaction) through index-based thresholds and propose a framework that is adaptable to other vulnerable coastal regions. Full article

With the continuous advancement of deep learning algorithms and the rapid growth of computational resources, deep learning technology has undergone numerous milestone developments, evolving from simple BP neural networks into more complex and powerful network models such as CNNs, LSTMs, RNNs, and GANs. In recent years, the application of deep learning technology in ionospheric modeling has achieved breakthrough advancements, significantly impacting navigation, communication, and space weather forecasting. Nevertheless, due to limitations in observational networks and the dynamic complexity of the ionosphere, deep learning-based ionospheric models still face challenges in terms of accuracy, resolution, and interpretability. This paper systematically reviews the development of deep learning applications in ionospheric modeling, summarizing findings that demonstrate how integrating multi-source data and employing multi-model ensemble strategies has substantially improved the stability of spatiotemporal predictions, especially in handling complex space weather events. Additionally, this study explores the potential of deep learning in ionospheric modeling for the early warning of geological hazards such as earthquakes, volcanic eruptions, and tsunamis, offering new insights for constructing ionospheric-geological activity warning models. Looking ahead, research will focus on developing hybrid models that integrate physical modeling with deep learning, exploring adaptive learning algorithms and multi-modal data fusion techniques to enhance long-term predictive capabilities, particularly in addressing the impact of climate change on the ionosphere. Overall, deep learning provides a powerful tool for ionospheric modeling and indicates promising prospects for its application in early warning systems and future research. Full article

This study analyzes the clean energy infrastructure resilience on Santa Cruz Island, located in the Galapagos archipelago, facing identified multi-natural hazard scenarios such as earthquakes, tsunamis, volcanic eruptions, and extreme weather events. Although Santa Cruz Island has a relatively modern energy infrastructure, its geographic location and lack of clear emergency management actions would significantly affect its performance. Risk assessment components, such as exposure and vulnerability, are also analyzed, highlighting the need for strategic interventions to ensure the continuity of energy supply and other essential services. Proved methodologies are used to propose action plans, including structural and non-structural solutions and simulations based on disaster scenarios. As a result, a series of strategies are revealed to strengthen the response and adaptation capacity of both critical infrastructure and the local community. These strategies hold the potential to ensure the island’s long-term energy security and sustainability, reducing its carbon footprint and instilling hope for a resilient future. Full article

Sedimentary records of event deposits are crucial for regional natural disaster risk assessments and hazard history reconstructions. After Super Typhoon Haiyan passed through the South China Sea in 2013, five gravity cores were collected along the typhoon path in the southern South China Sea basin (>3800 mbsl). The results showed that Super Typhoon Haiyan deposits with clear graded bedding are preserved at the top of all cores. The thickness of the typhoon layers ranges from 20 to 240 cm and is related to changes in typhoon intensity. The lack of river-connected submarine canyon systems limited the transportation of terrestrial sediments from land to sea. Super Typhoon Haiyan-induced large surface waves played an important role in carrying suspended sediment from the Philippines. The Mn-rich layers at the bottom of the typhoon layers may be related to the soil and rock composition of the Palawan region, which experienced tsunami-like storm surges caused by Super Typhoon Haiyan. These Mn-rich layers may serve as a proxy for sediment export from large-scale extreme terrigenous events. This study provides the first sedimentary record of extreme typhoon events in the deep ocean, which may shed light on reconstructing regional hazard history. Full article

The available historical documents for the city of Alexandria indicate that it was damaged to varying degrees by several (historical and instrumentally recorded) earthquakes and by highly destructive tsunamis reported at some places along the Mediterranean coast. In this work, we applied the neo-deterministic seismic hazard analysis (NDSHA) approach to the Alexandria metropolitan area, estimating ground motion intensity parameters, e.g., peak ground displacement (PGD), peak ground velocity (PGV), peak ground acceleration (PGA), and spectral response, at selected rock sites. The results of this NDSHA zonation at a subregional/urban scale, which can be directly used as seismic input for engineering analysis, indicate a relatively high seismic hazard in the Alexandria region (e.g., 0.15 g), and they can provide an essential knowledge base for detailed and comprehensive seismic microzonation studies at an urban scale. Additionally, we established detailed tsunami hazard inundation maps for Alexandria Governorate based on empirical relations and considering various Manning’s Roughness Coefficients. Across all the considered scenarios, the average estimated time of arrival (ETA) of tsunami waves for Alexandria was 75–80 min. According to this study, the most affected sites in Alexandria are those belonging to the districts of Al Gomrok and Al Montazah. The west of the city, called Al Sahel Al Shamally, is less affected than the east, as it is protected by a carbonate ridge parallel to the coastline. Finally, we emphasize the direct applicability of our study to urban planning and risk management in Alexandria. Our study can contribute to identifying vulnerable areas, prioritizing mitigation measures, informing land-use planning and building codes, and enhancing multi-hazard risk analysis and early warning systems. Full article

Tsunamis are destructive oceanic hazards caused by underwater disturbances, mainly earthquakes. A deterministic tsunami hazard assessment for the United Arab Emirates (UAE), due to the Makran Subduction Zone (MSZ), was conducted based on the history of earthquakes in the region and considering the rapid development and urbanization of the east coast of the UAE. A variety of earthquake source scenarios was modeled, involving moment magnitudes of 8.2, 8.8, and 9.2. Tsunami travel time (TTT), run-up, flow depth, and inundation maps were generated to pinpoint the areas susceptible to tsunami hazards for the eastern coastal cities of Kalba, Al Fujairah, Khor Fakkan, and Dibba. The results show that the worst-case M_w 9.2 earthquake in a full MSZ rupture scenario resulted in an average TTT of 37 min, a maximum run-up height of 2.55 m, a maximum flow depth of 2.2 m, and a maximum inundation distance of 253 m on the east coast of the UAE. The M_w 8.2 western MSZ earthquake and the M_w 8.8 eastern MSZ earthquake scenarios were of less significant impact. These findings provide new insights into tsunami hazard assessment and are expected to play a vital role in advancing sustainable development in the region by providing key information for stakeholders and authorities as they highlight the need for enhanced tsunami mitigation and preparedness measures to reduce the potential impact of future tsunamis on the UAE. Full article

The Arctic region, including vast shelf zones, has enormous resource and transport potential and is currently key to Russia’s strategic development. This region is promising and attractive for the intensification of global economic activity. When developing this region, it is very important to avoid emergency situations that could result in numerous negative environmental and socio-economic consequences. Therefore, when designing and constructing critical infrastructure facilities in the Arctic, it is necessary to conduct high-quality studies of potential geohazards. This paper reviews and summarizes the scattered information on the main geohazards in the Russian sector of the Arctic Ocean, such as earthquakes, underwater landslides, tsunamis, and focused fluid discharges (gas seeps), and discusses patterns of their spatial distribution and possible relationships with the geodynamic setting of the Arctic region. The study revealed that the main patterns of the mutual distribution of the main geohazards of the Russian sector of the Arctic seas are determined by both the modern geodynamic situation in the region and the history of the geodynamic evolution of the Arctic, namely the formation of the spreading axis and deep-sea basins of the Arctic Ocean. The high probability of the influence of seismotectonic activity on the state of subsea permafrost and massive methane release is emphasized. This review contributes toward better understanding and progress in the zoning of seismic and other geological hazards in the vast Arctic seas of Russia. Full article

Tsunami maps provide critical information about tsunami hazards, potential inundation areas, and safe evacuation routes, yet little research has addressed how different user groups perceive and interpret these maps. Using a questionnaire distributed to 181 participants (24 experts—EXs and 157 general users—GUs) and the chi-square (χ²) test, this research explored their understanding and perception of map elements, symbology, probabilistic data, and uncertainty communication. The results show that while both groups generally understand the maps, significant differences exist in their perception of essential map elements, such as evacuation routes, safe zones, and technical data. On average, EXs identified 7.38 elements that evacuation maps should contain, consistently emphasizing the need for more detailed information, whereas GUs preferred simplicity, selecting an average of 5.11 elements. These results highlight the need to balance detail and clarity in map design to serve both user groups effectively. Notably, the results suggest that at least 33% of EXs and 47% of GUs did not clearly distinguish between tsunami hazard and evacuation maps, highlighting the need for clearer map design and terminology. The study also revealed challenges in communicating probabilistic data and uncertainty to non-experts, suggesting the need for improved methods to present this information effectively. Full article

Density currents, fluid flows driven by differences in density, play a crucial role in disaster prevention for water pollution and tsunami mitigation, particularly due to thermal releases from power plants. Understanding their dynamics is pivotal for effective mitigation strategies. While the influence of seabed and lake bottom topography on density currents is well-studied, research on how embankment shapes affect these currents has been limited. This study aimed to fill this gap by experimentally and numerically analyzing the flow dynamics of density currents using various embankment shapes in a controlled water tank environment. The findings revealed distinct variations in density perturbation across different embankment shapes. Specifically, density currents exhibited reduced head velocities in embankments shaped as right-angled triangles, rectangles, and L-shapes, in that sequential order. This research underscores the significance of embankment design in modifying density currents, offering valuable insights for optimizing disaster management strategies related to water pollution and tsunami hazards induced by thermal effluents from industrial sources. Full article