Search Results (16)

This study investigated the complex interactions among tsunamis, debris, and coastal building structures under extreme hydrodynamic conditions. We performed numerical simulations to explore the influence of varying wave conditions, debris, and building designs to identify the most vulnerable parts of a building structure. The three-dimensional coupled fluid–structure–sediment–seabed interaction model (FS3M) was employed to simulate these interactions and validated against physical experimental data to ensure accuracy. The results revealed that debris significantly altered the wave impact dynamics, increasing the force exerted on buildings regardless of their structural features. This study provides relevant insights into the effectiveness of different building layouts in mitigating damage, highlighting the critical role of buildings with internal walls perpendicular to the wave direction, which significantly mitigated the tsunami’s impact at specific regions. Full article

When a tsunami occurs, people can enter floating shelters and save their lives. Tsunami shelters consisting of thin-walled fiber-reinforced plastic (FRP) spherical shells have been developed and are currently in use. In this study, a novel three-layer laminated spherical tsunami shelter and its fabrication method have been proposed as an alternative to the conventional thin-walled spherical FRP tsunami shelter. First, the inner and outer layers were made of thin-walled stainless-steel spherical shells using the integral hydro-bulge-forming (IHBF) method. The inter-layers between the inner and outer layers were filled with elastic rubber to provide a laminated spherical tsunami shelter with elastic cushioning layers. After the fabrication process was developed, a laminated spherical tsunami shelter with a plate thickness of 1.0 mm, an inner spherical shell design radius of 180 mm, and an outer spherical shell design radius of 410 mm was fabricated. The shape accuracy of the process was determined. The roundness values of the inner and outer layers of the spherical shell were 0.88 and 0.85 mm, respectively. The measured radii of the actual inner and outer spherical shells were 180.50 and 209.97 mm, respectively, and the errors between the design and measured radii were 0.28% and −0.01%. In this study, acceleration sensors were attached to the inner and outer layers of the processed, laminated spherical tsunami shelter. A hammer impact load was applied to the outer layer, and the response acceleration values measured by the acceleration sensors in the inner and outer layers were compared. It was confirmed that the response acceleration value of the inner layer was 10.17% smaller than that of the outer layer. It was then verified that the spherical tsunami shelter proposed in this study has a good cushioning effect and processing performance. Full article

In large-scale disasters, such as earthquakes and tsunamis, quick and sufficient transportation of emergency relief supplies is required. Logistics activities conducted to quickly provide appropriate aid supplies (relief goods) to people affected by disasters are known as humanitarian logistics (HL), and play an important role in terms of saving the lives of those affected. In the previous last-mile distribution of HL, supplies are transported by trucks and helicopters, but these transport methods are sometimes not feasible. Therefore, the use of unmanned aerial vehicles (UAVs) to transport supplies is attracting attention due to their convenience regardless of the disaster conditions. However, existing transportation planning that utilizes UAVs may not meet some of the requirements for post-disaster transport of supplies. Equitable distribution of supplies among affected shelters is particularly important in a crisis situation, but it has not been a major consideration in the logistics of UAVs in the existing study. Therefore, this study proposes transportation planning by introducing three crucial performance metrics: (1) the rapidity of supplies, (2) the urgency of supplies, and (3) the equity of supply amounts. We formulated the routing problem of UAVs as the multi-objective, multi-trip, multi-item, and multi-UAV problem, and optimize the problem with Q-learning (QL), one of the reinforcement learning methods. We performed reinforcement learning for multiple cases with different rewards and quantitatively evaluated the transportation of each countermeasure by comparing them. The results suggest that the model improved the stability of the supply of emergency relief supplies to all evacuation centers when compared to other models. Full article

Following the Great East Japan Earthquake, vertical evacuation shelters (VES) were constructed to reduce tsunami risk. Childcare centers (CCs) in the inundation area are required to evacuate to the nearest VES in the event of a tsunami. The study aim was to identify CCs and VES predicted to be inundated by a Nankai Trough earthquake-generated tsunami, and to clarify CC inundation risk. We identified 52 (45.6%) CCs in the tsunami inundation area and found that 14 (25.9%) would evacuate toward the tsunami. If the walking speed was 2.24 km/h and a 0.3 m tsunami arrived in 10 min, nine (17.3%) CCs would be late to safe evacuation. If the tsunami arrival time was 20 min, four (7.7%) CCs would have late evacuation. At a walking speed of 1.00 km/h, 38 (73.1%) and 20 (38.5%) CCs would have late evacuation, with tsunami arrival times of 10 min and 20 min, respectively. Evacuation direction is important in avoiding tsunami damage. An evacuation strategy is needed that evacuates people away from the tsunami, and takes into account children’s age, walking speed, and evacuation method. The evaluation of tsunami risk in this study may support the development of tsunami countermeasures in other coastal areas with latent tsunami risks. Full article

On 22 December 2018, the volcanic eruption of Anak Krakatoa in the Sunda Strait, Indonesia, triggered a tsunami causing 437 deaths. The highest death toll and the second highest number of damaged houses were recorded in Panimbang. This study proposes optimum evacuation shelters to reduce the mortality rate. A digital elevation model (DEM) and information dataset are used. The suggested horizontal evacuation shelters (HESs) are places of worship, schools, and government offices. Multimodal agent-based modelling (ABM), to analyse the sensitivity of parameters and the effect of vertical evacuation shelters (VESs) under multiple scenarios, is presented for the volcanic tsunami in December 2018. A tsunami hazard map is created by combining relative weights and parameter scores for topography, slope, and the distance from the shoreline and rivers. In the ABM results, the transportation mode choice depicts a significant decrease in the number of casualties. The mortality rate is sensitive to the milling time caused by delay time τ and agent decision-making time σ. VESs are proposed at the hot spots based on the location of deaths in the sensitivity tests and the high and very-high risk zones in the hazard map. As a result, combinations of VESs and HESs show a decrement in the number of deaths by 1.2–2 times compared to those with HESs only. The proposed VESs in the study area have a significant positive impact on decreasing the mortality rate. Full article

In spite of the significant number of studies focused on the 1755 earthquake and tsunami, there are still many unknowns regarding this event in Lisbon, Portugal. Thus, in this research the authors compiled historical documents, including some that had never been analyzed, complemented with a field survey and tsunami numerical modeling at the historical civil parish of Santo Estevão, Lisbon. It was possible to identify 13 buildings, including three religious buildings and five palaces. Furthermore, the new data showed that contradicting the general idea, the earthquake caused significant damage to the selected territory because the number of households decreased by 52%. The number of residents decreased to about 51%, and in 1756, 1041 residents were still living in 297 temporary shelters. There were more than 44 dead and 1122 residents were unaccounted for. The fire did not hit the area, and the tsunami numerical model results were validated by the historical accounts and cartography, which indicate that the coastal area of the studied area was not significantly inundated by the tsunami. The consultation of historical documents that had never been analyzed by contemporary researchers provides a breakthrough in the knowledge of the event since it allowed a very detailed analysis of the disaster impact. Full article

An earthquake with a magnitude of 8 or 9 is predicted to occur near the Ryukyu Islands in Japan, for which the Okinawa Prefecture is preparing countermeasures. Evacuating people to a safe shelter within the tsunami arrival time is a crucial countermeasure. This study aims to understand the vulnerabilities of patients with chronic respiratory diseases in southern parts of Okinawa during a tsunami evacuation, thereby calculating evacuation distance of vulnerable patients and creating individual evacuation plans. Data for chronic respiratory patients obtained in July 2021 from the hospitals in Okinawa Prefecture include age, gender, diagnosis, residence, nearest tsunami shelter, oxygen flow at rest and walking, and maximum walking distance for 6 min based on a 6-min walk test. A quantum geographic information system was used for mapping the data. The survival potential of patients with chronic respiratory disease was evaluated by using a tsunami inundation depth of one meter and the distance within which an evacuation can be performed until the first tsunami wave reaches the nearest evacuation shelter. Results revealed a low survival potential for respiratory disease patients under the current tsunami evacuation plan. The study suggests creating an individual evacuation plan for vulnerable patients involving families and medical staff and then conducting a drill for improving the plan. Full article

Three-dimensional (3D) modeling of tsunami events is intended to promote tsunami safety. However, the developed 3D modeling methods based on Computational Fluid Dynamics and photorealistic particle visualization have some weaknesses, such as not being similar to the original environment, not measuring the wave’s end point, and low image accuracy. The method for 3D modeling of tsunamis that results from this research can fulfil those weaknesses because it has advantages, such as being able to predict the end point of waves, similar to the original environment, and the height and area of inundation. In addition, the method produces more detailed and sharper spatial data. Modeling in this research is conducted using Agisoft Metashape Professional software to a produce 3D orthomosaic from pictures taken with Unmanned Aerial Vehicle (UAV) technique or drone (photogrammetry), and 3ds max software is used for wave simulation. We take a sample of an area in Cilacap, Indonesia that was impacted by the 2006 southwest coast tsunamis and may be vulnerable to future big megathrust earthquakes and tsunamis. The results could be used to provide several benefits, such as the creation of evacuation routes and the determination of appropriate locations for building shelters. Full article

Earthquake-induced tsunamis have the potential to cause extensive damage to natural and built environments and are often associated with fatalities, injuries, and infectious disease outbreaks. This review aims to examine the occurrence of respiratory infections (RIs) and to elucidate the risk factors of RI transmission following tsunamis which were induced by earthquakes in the last 20 years. Forty-seven articles were included in this review and referred to the RIs emergence following the 2004 Sumatra-Andaman, the 2009 Samoa, and the 2011 Japan earthquakes. Polymicrobial RIs were commonly detected among near-drowned tsunami survivors. Influenza outbreaks were commonly detected during the influenza transmission period. Overcrowded conditions in evacuation centers contributed to increased acute RI incidence rate, measles transmission, and tuberculosis detection. Destruction of health care infrastructures, overcrowded evacuation shelters, exposure to high pathogen densities, aggravating weather conditions, regional disease endemicity, and low vaccination coverage were the major triggering factors of RI occurrence in post-tsunami disaster settings. Knowledge of risk factors underlying RIs emergence following earthquake-induced tsunami can contribute to the implementation of appropriate disaster prevention and preparedness plans characterized by sufficient environmental planning, resistant infrastructures, resilient health care facilities, and well-established evacuation centers. Global and local disease surveillance is a key prerequisite for early warning and protection against RIs’ emergence and transmission in tsunami-prone areas. Full article

In the current study, we sought to identify special needs and safe evacuation conditions for children with neurodevelopmental disorders (CNDs) along Japan’s tsunami-prone Pacific coast. A survey and spatial analysis were used to collect data of CNDs (n = 47) and their caregivers. Areas predicted to be flooded in a tsunami, as well as evacuation routes to emergency shelters for vulnerable people (ESVPs), were mapped using geographic information systems (GIS). Our results showed that five professional staff were needed to support 33 CNDs requiring 135.9 m² of ESVP space. Critical safety factors were altitude, vertical evacuation, accessibility to ESVPs, and nonexistence of estuaries in the direction of evacuation. GIS-based spatial analysis and evacuation modeling for disaster preparedness and training plans that involve nurses are essential. Full article

Western Australia is susceptible to tsunamis from seismic sources that originate from distant sources including the Sunda Arc. Many surface and subsurface topographic ocean features are located between the Australian continent and locations where tsunamigenic earthquakes occur. These include the Venin Meinesz Seamounts (including Christmas Island) and Horizon Ridge, Exmouth, Zenith and Cuvier Plateaus. Numerical simulations of idealised tsunamigenic earthquakes along the Sunda Arc revealed that these topographic features have a large influence on the distribution of tsunami heights, propagating speeds and energy distribution. The interaction between tsunami waves and Venin Meinesz Seamounts and Horizon Ridge, located close to the earthquake locations, scatter the tsunami energy into several beams. Exmouth Plateau acts as a focusing feature to increase wave heights between North West Cape and Barrow Island whilst Cuvier Plateau deflects energy towards Shark Bay. Although Zenith Plateau has a local effect, it does not influence tsunami waves along the coast. Southwest Australia is “sheltered” from the direct effect of tsunami waves from Sunda Arc due to the combined effects of the Seamounts and Cuvier Plateau in the scattering and refraction of tsunami waves. Full article

The ability of individuals to manage and rebuild their lives after a disaster depends on environmental factors, as well as their own psychological characteristics. A psychometric questionnaire to measure personality traits relevant to disaster survival was proposed based on a large-scale investigation of survivors of the 2011 Great East Japan Earthquake (Sugiura et al. 2015). This tool, the Power to Live with Disasters questionnaire, measures eight personality characteristics that are beneficial for coping with disasters. However, this instrument has not been optimised for practical use; it is long and lacks benchmark scores for the general population. Thus, we developed a concise, 16-item version of the Power to Live with Disasters questionnaire through reanalysis of the 2011 Great East Japan Earthquake survivor data and an additional Web-based survey to obtain normative data from 1200 respondents drawn from the general population of Japan. The scores obtained from the short-form version of the questionnaire successfully replicated the results of the long-form version; eight distinct personality characteristics correlated well with several items associated with “successful survival” of the 2011 earthquake and tsunami. The normative data of the full- and short-version questionnaires were also highly correlated. We propose use of the shortened questionnaire to determine the personality traits critical for survival in the face of unexpected, life-threatening situations caused by natural disasters. Our questionnaire could be useful in schools and other public settings to enhance disaster-mitigation efforts and resilience to disasters in the general population. Full article

The 2004 Indian Ocean tsunami caused massive morphological changes around the coast of Sumatra, Indonesia. This research investigates the coastal morphological changes in the Banda Aceh area via coupling a hydrodynamic model with a sediment transport module. The Cornell Multigrid Coupled Tsunami Model (COMCOT) was coupled with the XBeach Model to simultaneously simulate sediment transport and the hydrodynamic process during the tsunami. The coupled model is known as COMCOT-SED. Field bathymetric data measured in 2006 were used to validate the coupled model. This study reveals that the tsunami’s impact was more severe on the eastern part of the coast, where it hit directly. Meanwhile, the western part of the coast suffered a lower impact because of the sheltering effects from a series of small islands and a headland to the north. This study has shown that the model results from COMCOT-SED are consistent with field data and show where the tsunami waves caused offshore erosion. Full article

Evacuation drills have been developed as part of many risk management programs. However, very few studies have paid attention to the process of evacuation drills. This study employs action research to examine a tsunami risk management strategy called the single-person drill, and applies new technologies in presenting related outcomes presented as multiscreen movies. The drill targets vulnerable people (i.e., older adults), during which a single evacuee moves to a shelter with the aid of a Global Positioning System (GPS) device. Evacuation routes, destination, and duration were used as parameters in an agent-based evacuation simulation shown on movies. The drill has been conducted 58 times in a coastal community (Okitsu, Kochi Prefecture), and 59 multiscreen movies were produced. An analysis of the effectiveness of the drill and related movies was done by collecting both quantitative and qualitative data. Results showed that, with a total of 163 respondents of a semistructured interview, 70.0% of residents were familiar with the drill, and 22.0% wanted to try it. The drill helped elderly people to improve self-efficacy in tsunami risk management, and generated two-way risk communication between experts and participants. This paper contributes new insights into understanding the importance of technology in tsunami risk management. Full article

The Earth’s land-cover is exposed to several types of environmental change, caused by either human activities or natural disasters. On 11 March 2011, an earthquake occurred about 130 km off the east coast of Sendai City in Japan. This earthquake was followed by a huge tsunami, which caused devastating damages over wide areas in the eastern coastline of Japan. Due to the occurrence of natural disasters across the world, there is a strong need to develop an automated algorithm for the fast and accurate extraction of changing landscapes within the affected areas. Such techniques can accelerate the process of strategic planning and primary services to move people into shelters and to carry out damage assessments as well as risk management during a crisis. Therefore, a variety of change detection (CD) techniques has been previously developed, based on various requirements and conditions. However, the selection of the most suitable method for change detection is not easy in practice. To the best of our knowledge, there is no existing CD approach that is both optimal and applicable in the cases of using a variety of optical and radar remote sensing images. To resolve these problems, an automated CD method based on a support vector data description (SVDD) classifier is proposed. This method uses the information contents of radar and optical data simultaneously by decision-level fusing of the change maps obtained from these data. For evaluating the efficiency of the proposed method and extract the damaged areas, the 2011 Sendai tsunami was considered. Various optical and radar remote sensing images from before and after the 2011 Sendai tsunami acquired by IKONOS and Radarsat-2 were used. The results confirmed the fundamental role and potential of using both optical and radar data for natural hazard damage detection applications. Full article