Understanding paleo-earthquakes in the Kuril Trench based on Late-Holocene tsunami deposits in the distal region from wave sources, northern Hidaka, Hokkaido, Japan.

Geological evidence, such as tsunami deposits, is crucial for studying the largest rupture zone of the Kuril Trench in Hokkaido, Japan, due to its poor historical record. Although 17th-century tsunami deposits are widely distributed across Hokkaido, the presence of multiple wave sources during that period, including the collapse of Mt. Komagatake, complicates the correlation with their wave sources. Understanding the regional distribution of these tsunami deposits can provide valuable data to estimate the magnitude of megathrust earthquakes in the Kuril Trench. The northern part of Hidaka, Hokkaido, where tsunamis from multiple wave sources are expected to overlap, is distant from the Kuril Trench. To clarify the depositional history of tsunami deposits in such distal areas, evaluating the influence of the depositional environments on the event layer preservation becomes even more critical. We conducted field surveys in Kabari, located in the northern Hidaka region, identifying three sand layers from the 10th to the 17th century and two layers dating beyond 2.3 thousand years ago. The depositional ages of most sand layers potentially correlate with tsunami deposits resulting from the Kuril Trench earthquakes. Utilizing reconstructed paleo-sea level data, we estimated that most sand layers reached approximately 2 m in height. However, it is noteworthy that the latest sand layer from the 17th century exhibited an unusual distribution, more than 3 m in height. This suggests a different wave source as the Mt. Komagatake collapse. The discovery of multiple sand layers and their distributions is crucial to constraining the maximum magnitude of giant earthquakes in the Kuril Trench and understanding the volcanic tsunami events related to Mt. Komagatake.

The 2024 Noto Peninsula Earthquake and the Strategy of Medical Assistance from the Tohoku University Hospital.

A moment magnitude (Mw) 7.5 earthquake (the Global IDentifire (GLIDE) number: # Q-2024-000001-JPN) struck the Noto Peninsula of Ishikawa Prefecture on 1 January 2024 at 16:10 (Japan Standard Time). The reversed fault, 150 km in length and subducting beneath the peninsula, resulted in maximum seismic intensity 7 shaking, triggered the tsunami, destroyed over 43 thousand buildings, and disrupted roads and lifelines. The disaster claimed 236 deaths, including 15 indirect disaster deaths as of Jan. 28, 2024. There were Disaster Base Hospitals (DBHs) in the region, which survived structurally but suffered from impaired functions and the surge of medical needs of affected people. The disaster medical system of Japan immediately responded and coordinated the hundreds of emergency medical teams (EMTs), i.e., the Japan Disaster Medical Assistance Team (DMAT), from all over the country. Tohoku University Hospital, which had the experience of the 2011 Great East Japan Earthquake (GEJE), joined the coordinated response, dispatching a chain of DMATs, which helped the medical and public health coordination in Wajima City. The medical and public health needs included injuries, non-communicable diseases, infectious diseases, mental health issues, and maternal and child health issues, which were similar in the affected communities in GEJE. Although the actual damage far exceeded expectations, the structural retrofitting and business continuity plans of DBHs and the coordinated response of the national disaster medical system enhanced the effectiveness of medical and public health response.

Application of connectivity index of cubic fuzzy graphs for identification of danger zones of tsunami threat.

Fuzzy graphs are very important when we are trying to understand and study complex systems with uncertain and not exact information. Among different types of fuzzy graphs, cubic fuzzy graphs are special due to their ability to represent the membership degree of both vertices and edges using intervals and fuzzy numbers, respectively. To figure out how things are connected in cubic fuzzy graphs, we need to know about cubic α-strong, cubic ß-strong and cubic δ-weak edges. These concepts better help in making decisions, solving problems and analyzing things like transportation, social networks and communication systems. The applicability of connectivity and comprehension of cubic fuzzy graphs have urged us to discuss connectivity in the domain of cubic fuzzy graphs. In this paper, the terms partial cubic α-strong and partial cubic δ-weak edges are introduced for cubic fuzzy graphs. The bounds and exact expression of connectivity index for several cubic fuzzy graphs are estimated. The average connectivity index for cubic fuzzy graphs is also defined and some results pertaining to these concepts are proved in this paper. The results demonstrate that removing some vertices or edges may cause a change in the value of connectivity index or average connectivity index, but the change will not necessarily be related to both values. This paper also defines the concepts of partial cubic connectivity enhancing node and partial cubic connectivity reducing node and some related results are proved. Furthermore, the concepts of cubic α-strong, cubic ß- strong, cubic δ-weak edge, partial cubic α-strong and partial cubic δ-weak edges are utilized to identify areas most affected by a tsunami resulting from an earthquake. Finally, the research findings are compared with the existing methods to demonstrate their suitability and creativity.

In the arena: contesting disaster creation in cities.

Space is a feature of all disasters, and it is through decisions on how space is developed, used, and reproduced that disasters manifest themselves. Critical urban theory sees urban space-cities-as an arena of contestation expressed through the relationship between people, power, and the built environment. Cities allow for an unpacking of this process of contestation through the interpretation of various temporal, spatial, social, and physical elements that together create complex issues and 'wicked problems'. In these urban spaces in all their complexity, disasters reveal both the worst injustices and inequalities present in a society. By drawing on three well-known cases-Hurricane Katrina in 2010; the Haiti earthquake in 2010; and the Great East Japan Earthquake and Tsunami in 2011-this paper not only explores the opportunities that critical urban theory presents for gaining a deeper understanding of disaster risk creation, but also it encourages disaster scholars to engage with it.

Strengthening tsunami maritime response and mitigation through inclusive stakeholder engagement: Lessons learned in Washington State.

Among the most vulnerable facilities to tsunami impacts are ports, harbours and marinas. The ability of maritime infrastructure to withstand a disaster and resume operations quickly plays a major factor in the recovery of the local community and economy in the short and long term. Despite this, little established guidance exists to assist the maritime community with addressing their tsunami risk in an actionable, site-specific manner. To close this gap and improve the resilience of its maritime community, Washington State has begun developing tsunami maritime response and mitigation strategies for major ports, harbours and marinas along its 3,200 miles of coastline. These strategies include detailed information about the location's specific tsunami risk, recommended guidance for vessel operators in the area, and tsunami mitigation and response recommendations ranked by their implementation feasibility for the maritime entity in question. Most importantly, the strategies are created through close collaboration with local key stakeholders, subject matter experts, local emergency management and state agencies to ensure a final deliverable that is accurate, thorough and, above all, useful to the local maritime entity and its tenants and users. As this paper will discuss, the lessons learned during the planning and delivery of these strategies provide valuable insight for professionals in the maritime, business continuity and emergency management fields, including how to conduct effective and inclusive stakeholder engagement, identify gaps and opportunities in resilience planning, and establish a deeper understanding of tsunami maritime risk and hazards.

Strategic coastal dike shape for enhanced tsunami overflow reduction.

Coastal dikes are an essential social infrastructure to mitigate tsunami damage. However, there are no clear guidelines on effective dike shapes for reducing tsunami overflow. To examine effective dike shapes, numerical simulations of the amount of tsunami overflow at coastal dikes are conducted with reference to tsunami waveforms caused by the Great East Japan Earthquake. Results reveal the relationship between the dike shape and the amount of the overflow; the mechanism of overflow reduction based on the velocity and water level distribution is also verified. The comparison of the seaward and landward slopes of coastal dikes reveals that the seaward slope has a greater impact on the overflow, and the seaward slope with a vertical wall or a wave return structure reduces the overflow by 5%-30% compared to the 1:2 (26.6°) seaward slope. The landward slope should be determined based on the tsunami scale and the scour related to the dike stability. Since tsunami inflow damages human life and social infrastructure, achieving the overflow reduction without increasing dike height is vital. Our work contributes to rational design guidelines for coastal dikes.

Exposure to the Indian Ocean Tsunami shapes the HPA-axis resulting in HPA "burnout" 14 years later.

Despite significant research on the effects of stress on the hypothalamic-pituitary-adrenal (HPA) axis, questions remain regarding long-term impacts of large-scale stressors. Leveraging data on exposure to an unanticipated major natural disaster, the 2004 Indian Ocean tsunami, we provide causal evidence of its imprint on hair cortisol levels fourteen years later. Data are drawn from the Study of the Tsunami Aftermath and Recovery, a population-representative longitudinal study of tsunami survivors who were living along the coast of Aceh, Indonesia, when the tsunami hit. Annual rounds of data, collected before, the year after and 2 y after the disaster provide detailed information about tsunami exposures and self-reported symptoms of post-traumatic stress. Hair samples collected 14 y after the tsunami from a sample of adult participants provide measures of cortisol levels, integrated over several months. Hair cortisol concentrations are substantially and significantly lower among females who were living, at the time of the tsunami, in communities directly damaged by the tsunami, in comparison with similar females living in other, nearby communities. Differences among males are small and not significant. Cortisol concentrations are lowest among those females living in damaged communities who reported elevated post-traumatic stress symptoms persistently for two years after the tsunami, indicating that the negative effects of exposure were largest for them. Low cortisol is also associated with contemporaneous reports of poor self-rated general and psychosocial health. Taken together, the evidence points to dysregulation in the HPA axis and "burnout" among these females fourteen years after exposure to the disaster.

Does disaster-related relocation impact mental health via changes in group participation among older adults? Causal mediation analysis of a pre-post disaster study of the 2016 Kumamoto earthquake.

BACKGROUND: Disaster-related relocation is associated with depression and post-traumatic stress disorder, especially in older adults. Disaster-related relocation often deprives survivors of opportunities for social group participation, potentially deteriorating their mental health. On the contrary, the relocation could also be an opportunity for optimizing social relationships, ending/reducing unwanted participation. This study examined the potential mediation effects of changing participation for the link of disaster-related relocation to mental health. METHODS: We analyzed a pre-post disaster dataset of functionally independent older adults from the Japan Gerontological Evaluation Study. Following the 2013 survey, a follow-up survey was conducted seven months after the 2016 Kumamoto earthquake (n = 828). RESULTS: The causal mediation analyses indicated that compared to no relocation, the relative risk for experiencing major depressive episodes among those relocating to temporary housing was 3.79 [95% confidence interval: 1.70-6.64] (natural direct effect). By contrast, the relative risk for those renewing (either ceased or started) group participation was 0.60 [95% CI: 0.34-0.94] (natural indirect effect). CONCLUSIONS: Optimization of social ties according to a renewal of group participation status might have protected older adults in temporary housing against depression.

Association between sense of coherence and health and well-being among older survivors of a natural disaster: a prospective outcome-wide study.

We examined whether pre-disaster Sense of Coherence (SOC) mitigated the impact of housing damage on health and well-being of older survivors after the 2011 Japan Earthquake and Tsunami. A panel survey was conducted in a city located 80 km west of the epicenter seven months before and three years after the disaster (3594 respondents). Among respondents with lighter property damage, higher SOC was inversely associated with mental distress (coefficient - 0.29, 95% CI (confidence interval) - 0.39, - 0.19, p < .01), unhappiness (coefficient - 0.33, 95% CI - 0.43, - 0.23, p < .01), low expectation of mutual help (coefficient - 0.17, 95% CI - 0.27, - 0.07, p < .01), and weak community attachment (coefficient - 0.20, 95% CI - 0.30, - 0.11, p < .01). Conversely, among those who experienced housing loss, higher SOC was no longer protectively associated with health and well-being. Loss of generalized resistance resources due to serious damage led to difficulties in stress coping.

Simulation of supply chain disruptions considering establishments and power outages.

In this paper, we simulate the economic loss resulting from supply chain disruptions triggered by the Great East Japan Earthquake (GEJE) in 2011, applying data from firm-level supply chains and establishment-level attributes to an agent-based model. To enhance the accuracy of the simulation, we extend data and models in previous studies in four ways. First, we identify the damage to production facilities in the disaster-hit regions more accurately by using establishment-level census and survey data and geographic information system (GIS) data on the damages caused by the GEJE and subsequent tsunami. Second, the use of establishment-level data enables us to capture supply chains between non-headquarter establishments in disaster-hit regions and establishments in other regions. Third, we incorporate the effect of power outages after the GEJE on production reduction, which exacerbated the effect of the supply chain disruption, particularly in the weeks immediately after the GEJE. Finally, our model incorporates sectoral heterogeneity by employing sector-specific parameters. Our findings indicate that the extended method can significantly improve the accuracy of predicting the domestic production after the GEJE, particularly due to the first three improvements utilizing various data sources, not because of the use of more sector-specific parameters. Our method can be applied to predict the economic effect of future disasters, such as the Nankai Trough earthquake, on each region more precisely.

Change in Geographic Accessibility to Dental Clinics Affects Access to Care.

Access to dental clinics is a feature of the neighborhood service environment that may influence oral health care utilization. However, residential selection poses a challenge to causal inference. By studying the involuntary relocation of survivors of the 2011 Great East Japan Earthquake and Tsunami (GEJE), we examined the association between changes in geographic distance to dental clinics and dental visits. Longitudinal data from a cohort of older residents in Iwanuma City directly impacted by the GEJE were analyzed in this study. The baseline survey was conducted in 2010, 7 mo before the occurrence of GEJE, and a follow-up was conducted in 2016. Using Poisson regression models, we estimated the incidence rate ratios (IRR) and 95% confidence intervals (CIs) for the uptake of denture use (as a proxy for dental visits) according to changes in distance from the nearest dental clinic to their house. Age at baseline, housing damage by the disaster, deteriorating economic conditions, and worsened physical activity were used as confounders. Among the 1,098 participants who had not worn dentures before the GEJE, 495 were men (45.1%), with a mean ± SD age at baseline of 74.0 ± 6.9 y. During the 6-year follow-up, 372 (33.9%) participants initiated denture use. Compared to those who experienced a large increase in distance to dental clinics (>370.0-6,299.1 m), a large decrease in distance to dental clinics (>429.0-5,382.6 m) was associated with a marginally significantly higher initiation of denture use among disaster survivors (IRR = 1.28; 95% CI, 0.99-1.66). The experience of major housing damage was independently associated with higher initiation of denture use (IRR = 1.77; 95% CI, 1.47-2.14). Improved geographic access to dental clinics may increase dental visits of disaster survivors. Further studies in non-disaster-affected areas are needed to generalize these findings.

Use of the HESPER Web to Assess Perceived Needs Immediately After Multiple Disaster Events in Fiji.

OBJECTIVE: In January 2022, Fiji was hit by multiple natural disasters, including a cyclone causing flooding, an underwater volcanic eruption, and a tsunami. This study aimed to investigate perceived needs among the disaster-affected people in Fiji and to evaluate the feasibility of the Humanitarian Emergency Settings Perceived Needs Scale (HESPER Web) during the early stage after multiple natural disasters. METHODS: A cross-sectional study using a self-selected, non-representative study sample was conducted. The HESPER Web was used to collect data. RESULTS: In all, 242 people participated. The number of perceived serious needs ranged between 2 and 14 (out of a possible 26), with a mean of 6 (SD = 3). The top 3 most reported needs were access to toilets (60%), care for people in the community who are on their own (55%), and distress (51%). Volunteers reported fewer needs than the general public. CONCLUSIONS: The top 3 needs reported were related to water and sanitation and psychosocial needs. Such needs should not be underestimated in the emergency phase after natural disasters and may require more attention from responding actors. The HESPER Web was considered a usable tool for needs assessment in a sudden onset disaster.

Bidirectional associations between post-traumatic stress symptoms and sleep quality among older survivors of the 2011 Great East Japan Earthquake and Tsunami.

STUDY OBJECTIVES: We sought to examine the bidirectional associations between post-traumatic stress symptoms (PTSS) and sleep quality in a sample of older disaster survivors. METHODS: We used 4 waves (2010, 2013, 2016, and 2020) of the Iwanuma Study, which included pre-disaster information and 9 years of follow-up data among older survivors of the 2011 Great East Japan Earthquake and Tsunami. Poisson regression analysis was used to examine the bidirectional associations between sleep problems and PTSS. RESULTS: Individuals reporting sleep problems before the disaster were more likely to develop PTSS after exposure to disaster trauma, while there was no effect modification, i.e. prevalence ratio for sleep problems did not differ by the magnitude of disaster damages. Individuals reporting sleep problems after the disaster were less likely to recover from PTSS, and more likely to develop the delayed onset of PTSS 5 years after the disaster. While individuals who recovered from PTSS 9 years after the disaster were still at slightly higher risk of having sleep problems compared to those who never had PTSS, none of the sleeping problems were found to be significantly prevalent after the Bonferroni correction. CONCLUSIONS: Pre-disaster sleep problems predicted PTSS onset independently of experiences of disaster trauma. The association between PTSS and sleep problems was bidirectional. Intervening to mitigate lingering sleep problems may benefit the recovery of disaster survivors from post-traumatic symptoms.

Major Causes of Death among Older Adults after the Great East Japan Earthquake: A Retrospective Study.

This retrospective study investigated the 3-year impact of the Great East Japan Earthquake (GEJE) of 2011 on deaths due to neoplasm, heart disease, stroke, pneumonia, and senility among older adults in the primarily affected prefectures compared with other prefectures, previous investigations having been more limited as regards mortality causes and geographic areas. Using death certificates issued between 2006 and 2015 (n = 7,383,253), mortality rates (MRs) and risk ratios (RRs) were calculated using a linear mixed model with the log-transformed MR as the response variable. The model included interactions between the area category and each year of death from 2010 to 2013. The RRs in the interaction significantly increased to 1.13, 1.17, and 1.28 for deaths due to stroke, pneumonia, and senility, respectively, in Miyagi Prefecture in 2011, but did not significantly increase for any of the other areas affected by the GEJE. Moreover, increased RRs were not reported for any of the other years. The risk of death increased in 2011; however, this was only significant for single-year impact. In 2013, decreased RRs of pneumonia in the Miyagi and Iwate prefectures and of senility in Fukushima Prefecture were observed. Overall, we did not find evidence of strong associations between the GEJE and mortality.

A framework to estimate a long-term power shortage risk following large-scale earthquake and tsunami disasters.

While power shortages during and after a natural disaster cause severe impacts on response and recovery activities, related modeling and data collection efforts have been limited. In particular, no methodology exists to analyze long-term power shortages such as those that occurred during the Great East Japan Earthquake. To visualize a risk of supply shortage during a disaster and assist the coherent recovery of supply and demand systems, this study proposes an integrated damage and recovery estimation framework including the power generator, trunk distribution systems (over 154 kV), and power demand system. This framework is unique because it thoroughly investigates the vulnerability and resilience characteristics of power systems as well as businesses as primary power consumers observed in past disasters in Japan. These characteristics are essentially modeled by statistical functions, and a simple power supply-demand matching algorism is implemented using these functions. As a result, the proposed framework reproduces the original power supply and demand status from the 2011 Great East Japan Earthquake in a relatively consistent manner. Using stochastic components of the statistical functions, the average supply margin is estimated to be 4.1%, but the worst-case scenario is a 5.6% shortfall relative to peak demand. Thus, by applying the framework, the study improves knowledge on potential risk by examining a particular past disaster; the findings are expected to enhance risk perception and supply and demand preparedness after a future large-scale earthquake and tsunami disaster.

Association between the extent of house collapse and urine sodium-to-potassium ratio of victims affected by the 2011 Great East Japan Earthquake and Tsunami: a cross-sectional study.

People who experience natural disasters have a high risk of developing cardiovascular diseases. We investigated the association between the extent of house collapse and urine sodium-to-potassium (UNa/K) ratio of 2011 Great East Japan Earthquake victims. We used the baseline survey data of the Tohoku Medical Megabank Project Community-Based Cohort Study of 29 542 individuals (aged 20-74 years) residing in the affected areas. The UNa/K ratio was calculated using spot urinary electrolyte values. Analysis of covariance was used to calculate the multivariate-adjusted geometric means of the UNa/K ratio in the following groups stratified according to the self-reported extent of house collapse: total collapse (TC), half collapse (HC), partial collapse (PC), and no damage (ND). Multivariable-adjusted odds ratios (ORs) for a high UNa/K ratio were calculated using logistic regression. The TC, HC, PC, and ND groups comprised 5 359 (18.1%), 3 576 (12.1%), 7 331 (24.8%), and 13 276 (44.9%) participants, respectively. The TC (3.33; 95% confidence interval [CI], 3.28-3.38), HC (3.37; 3.30-3.43), and PC (3.32; 3.28-3.37) groups had significantly higher multivariate-adjusted geometric means of the UNa/K ratio than the ND (3.24; 3.21-3.27) group. The multivariable-adjusted ORs (95% CIs) for a high UNa/K ratio in the TC, HC, and PC groups vs. the ND group were 1.07 (0.99-1.15), 1.20 (1.11-1.31), and 1.20 (1.12-1.28), respectively. Similar associations between house collapse and UNa/K ratio were observed for both sexes. We report that victims of a natural disaster tend to have a diet with high sodium-to-potassium ratio.

Post-Disaster Mental Health and Dietary Patterns among Older Survivors of an Earthquake and Tsunami.

OBJECTIVES: Research suggests that cardiometabolic disease risks are elevated among survivors of natural disasters, possibly mediated by changes in diet. Using the Brief Dietary History Questionnaire, we examined (1) dietary patterns among older survivors of the 2011 Great East Japan Earthquake and Tsunami, and (2) the contribution of posttraumatic stress symptoms (PTSS)/depressive symptoms, as well as relocation to temporary housing on dietary patterns and (3) gender differences in the associations. DESIGN, SETTING AND PARTICIPANTS: Data came from a prospective cohort study of 1,375 survivors aged 65-89 years (44.6% male). MEASUREMENTS: PTSS/depression onset was evaluated in 2013, 2.5 years after the disaster. Dietary data was collected with a self-administered brief-type diet history questionnaire in 2020. A principal component analysis identified three posterior dietary patterns. RESULTS: Diet 1 consisted of high intake of vegetables, soy products, and fruits; Diet 2 consisted of carbohydrate-rich foods and snacks/sweets; Diet 3 consisted of high intake of alcoholic beverages, meat, and seafood. Least-squares linear regression revealed that individuals with PTSS/depression were less likely to exhibit Diet 1, while individuals with PTSS were more likely to exhibit Diet 2 and 3. Especially, males who had depression showed an unhealthy dietary pattern. Those who have lived in a trailer-style temporary housing reported less consumption of Diet 3. CONCLUSION: Survivors of disaster with symptoms of mental illness tended to exhibit less healthy dietary patterns after 9 years. Diet varied by type of post-disaster mental illness, gender, and current social circumstances. We lacked pre-disaster BDHQ data, which is a limitation.

Heterogenous effects of the Great East Japan earthquake on prosociality of people depending on their age.

This study investigates the instability of prosociality in the real world by looking at the age-specific non-linear relationship between disaster exposure and prosocial behavior. We employed unique microdata from two communities in Japan that were hit by the Great East Japan Earthquake and Tsunami disaster in 2011. Exploiting exogenous variations in disaster exposure, we find age-specific heterogeneous effects of disaster exposure on prosocial behavior captured by the behavior of sending New Year's cards as well as attitudinal survey questions. Among the older groups, disaster damages undermine prosociality, whereas the younger groups show reinforced prosocial behaviors. These findings can be explained consistently by combining two possible determinants of prosocial behavior: pure or impure altruism and self-enforcements in repeated interactions at workplaces. Age information can help disentangle these two elements at least partially.