Great East Japan Earthquake Research Articles

As Teachers Not Tourists: Creating Knowledge During a Short-Term Study Abroad Program

Here, I address the call for teacher education programs to feature international elements to help pre-service teachers craft powerful classroom instruction and successfully work with students from culturally diverse backgrounds. I share a qualitative investigation of participants’ experiences during a short-term study abroad program in Japan that explored contemporary disaster preparedness as a result of the Great East Japan Earthquake and Tsunami. The program sponsors, the Japanese Ministry of Foreign Affairs, hoped participants would develop an appreciation for the people and culture of Japan while they learned about disaster preparedness. I wondered if collecting curriculum items during a short-term study abroad program could help social studies pre-service teachers create—not just receive—historical domain knowledge? In Japan, participants collected items to use as featured resources around which they designed classroom activities for secondary students. Their activities demonstrated three levels of second-order historical domain knowledge and two elements of civic competence. This study suggests that pre-service teachers with no previous international experience may require explicit modeling and scaffolding to translate their short-term study abroad participation into dynamic learning. Another implication is that participants need strong support to consider the photographs they capture as artifacts of contemporary material culture.

Trends in mortality rates and correlations between intracranial injuries and external causes: A Japanese population study.

The age-standardized incidence of head trauma in 2016 was 369 per 100,000 people worldwide. The Western Pacific region, including Japan, had the highest incidence. This study aimed to extract ICD-10 code data for intracranial injury (S06) and external causes of morbidity and mortality (V01-Y89), analyze their characteristics and interrelationships, and contribute to these diseases' prevention, treatment, and prognosis. The number of deaths according to injury type and external cause type of intracranial injury published by the Japanese government was statistically analyzed using JoinPoint, and univariate distribution and multivariate correlation were conducted using JMP Software. From 1999-2021, there was a downward trend in the number of deaths because of intracranial injuries: mortality from intracranial injuries was higher among those aged ≥65 years. Conversely, mortality from intracranial injuries was lower among those aged ≤14 years. Among deaths from intracranial injury, mortality from diffuse brain injury and traumatic subdural hemorrhage was more common. Among deaths from external causes of intracranial injury, mortality from falls, transport accidents, and other unforeseen accidents was more common. Mortality because of intracranial injuries increased significantly during the 2011 Great East Japan Earthquake. For some age groups and sexes, there were significant inverse correlations of mortality with traumatic subdural hemorrhage and traumatic subarachnoid hemorrhage for transport accidents, intentional self-harm and assault, and diffuse brain injury and focal brain injury for falls. We believe that the data presented in this study will be useful for preventing and treating intracranial injuries and for developing administrative measures to reduce intracranial injuries.

Investigating Post-Disaster Reconstruction since the 2011 Great East Japan Earthquake: A Study on the Ōtsuchi-chō, Iwate Prefecture through Timelines

Since the 2011 Great East Japan Earthquake, 13 years have passed, and many areas have completed post-disaster reconstruction. Therefore, it is necessary to further summarise and analyse the experiences gained from this post-disaster reconstruction. This study conducted door-to-door interviews with residents of Ōtsuchi-chō, Iwate Prefecture, in the 13 years following the earthquake. It recorded the residents’ perspectives on post-disaster reconstruction and its shortcomings. By collecting locally published materials like newspapers, and local government records and integrating them with interview records, the first “Great East Japan Earthquake Timeline” for Ōtsuchi-chō was compiled. We primarily divided this timeline into the following three phases: the disaster and early reconstruction period (2011), the mid-reconstruction period (2012–2015), and the late reconstruction period (2016–Present). This timeline has yielded the following results: firstly, some issues have arisen during this prolonged reconstruction process. For example, continuous relocation hinders community rebuilding, especially in the context of an ageing society. Secondly, the “Ōtsuchi-chō Reconstruction Timeline” was created, which can be used for post-disaster reconstruction in contemporary Japanese villages facing severe ageing. This timeline provides a clear understanding of how disaster-affected areas can rebuild housing and infrastructure, and recover economically. It offers guidance for the reconstruction of Japanese villages after a disaster. Therefore, post-disaster reconstruction in the region should accelerate infrastructure development and continuously listen to residents’ voices, providing corresponding services to make reconstruction comprehensive and specific. At the same time, it also contributes to the post-disaster reconstruction of villages in other developed countries.

Integration of Smart City Technologies with Advanced Predictive Analytics for Geotechnical Investigations

This paper addresses challenges and solutions in urban development and infrastructure resilience, particularly in the context of Japan’s rapidly urbanizing landscape. It explores the integration of smart city concepts to combat land subsidence and liquefaction, phenomena highlighted by the 2011 Great East Japan Earthquake. Additionally, it examines the current situation and lack of geoinformation and communication technology in the concept of smart cities in Japan. Consequently, this study employs advanced technologies, including smart sensing and predictive analytics through kriging and ensemble learning, with the objective of enhancing the precision of geotechnical investigations and urban planning. By analyzing data in Setagaya, Tokyo, it develops predictive models to accurately determine the depth of bearing layers that are critical to urban infrastructure. The results demonstrate the superiority of ensemble learning in predicting the depth of bearing layers. Two methods have been developed to predict undetected geographic data and prepare ground reality and digital smart maps for the construction industry to build smart cities. This study is useful for real-time analysis of existing data, for the government to make new urban plans, for construction companies to conduct risk assessments before doing their jobs, and for individuals to obtain real-time geographic data and hazard warnings through mobile phones and other means in the future. To the best of our knowledge, this is the first instance of predictive analysis of geographic information being conducted through geographic information, big data technology, machine learning, integrated learning, and artificial intelligence.

Experimental Study on Erosion Process of Expressway Embankment Subjected to Tsunami After Earthquake

On March 11, 2011, the Great East Japan Earthquake triggered tsunamis that reached extensive areas along Japan’s Pacific coast. There have been instances where embankments built on plains for expressways mitigated the impact of tsunami damage. In the vicinity of the Sendai-tobu highway, the presence of an embankment approximately 10 m high altered the course of the advancing tsunami, thereby preventing flooding. Establishing a multiplied defense system using road embankments necessitates understanding the deformation and collapse mechanisms of road embankments impacted by tsunamis following seismic motion. In this study, overtopping experiments were conducted by first applying seismic motion to model embankments, followed by introducing the first wave of breaking bores, and then simulating prolonged overtopping by the tsunami. The experimental findings indicated that within the embankments impacted by the tsunami, there was an immediate increase in what is presumed to be pore air pressure following the arrival of the breaking bores, followed by a rise in pore water pressure during subsequent overtopping. Moreover, embankments subjected to seismic motion exhibited accelerated erosion following the overtopping. These results imply that when embankments settle due to an earthquake, leading to relatively higher anticipated inundation depths and the potential for overtopping, it is crucial to implement measures to prevent the settlement of the crest for embankments expected to serve as part of a multiplied defense system.

Associations between housing and psychological damage by earthquake and modifiable risk factors for dementia in general older adults: Tohoku Medical Megabank community-based cohort study.

To evaluate the association between housing and psychological damage caused by the Great East Japan Earthquake (GEJE) and modifiable risk factors (MRFs) of dementia for general population of older adults. This cross-sectional study enrolled 29 039 community-dwelling older adults (mean age 69.1 ± 2.9 years, 55.5% women). We evaluated disaster-related damage (by complete or not complete housing damage) and psychological damage (by post-traumatic stress reaction [PTSR]) after the GEJE using a self-report questionnaire. MRFs encompassed the presence of depression, social isolation, physical inactivity, smoking, and diabetes. We examined the association between disaster-related damage and MRFs using ordinary least squares and modified Poisson regression models adjusted for sociodemographic and health status variables. Complete housing damage and PTSR were identified in 2704 (10.0%) and 855 (3.2%) individuals, respectively. The number of MRFs was significantly larger for the individuals with complete housing damage (β = 0.23; 95% confidence interval [CI]: 0.19-0.27) and PTSR (β = 0.60; 95% CI: 0.53-0.67). Prevalence ratios (PRs) for depression and physical inactivity were higher in individuals with complete housing damage. The PRs for all domains of the MRFs were significantly higher in individuals with PTSR. Housing and psychological damage caused by the GEJE were associated with an increased risk factor of dementia. To attenuate the risk of dementia, especially among older victims who have experienced housing and psychological damage after a disaster, multidimensional support across various aspects of MRFs is required. Geriatr Gerontol Int 2024; 24: 509-516.

Primary care clinic visits in formerly evacuated areas due to radiation disaster following the Great East Japan Earthquake: A retrospective descriptive study.

Radiation disasters pose distinctive medical challenges, requiring diverse care approaches. Beyond radiation exposure assessment, addressing health impacts due to lifestyle changes, especially among vulnerable populations, is vital. Evacuation orders issued in radiation-affected areas introduce unique healthcare dynamics, with their duration significantly influencing the recovery process. Understanding evolving patient demographics and medical needs after lifting evacuation orders is crucial for post-disaster care planning. Minamisoma Municipal Odaka Hospital, located 13 to 20 km from Fukushima Daiichi Nuclear power plant in a post-evacuation zone, was greatly affected by the Great East Japan Earthquake and subsequent radiation disaster. Data were retrospectively collected from patient records, including age, gender, visit date, diagnoses, and addresses. Patient records from April 2014 to March 2020 were analyzed, comparing data before and after the July 2016 evacuation order lift. Data was categorized into pre and post-evacuation order lifting periods, using International Classification of Diseases, Tenth Edition codes, to identify the top diseases. Statistical analyses, including χ-square tests, assessed changes in disease distributions. Population data for Odaka Ward and Minamisoma City fluctuated after lifting evacuation orders. As of March 11, 2011, Odaka Ward had 12,842 residents (27.8% aged 65+ years), dropping to 8406 registered residents and 2732 actual residents by April 30, 2018 (49.7%). Minamisoma City also saw declines, with registered residents decreasing from 71,561 (25.9%) to 61,049 (34.1%). The study analyzed 11,100 patients, mostly older patients (75.1%), between 2014 and 2020. Post-lifting, monthly patient numbers surged from an average of 55.2 to 213.5, with female patients increasing from 33.8% to 51.7%. Disease patterns shifted, with musculoskeletal cases declining from 23.8% to 13.0%, psychiatric disorders increasing from 9.3% to 15.4%, and trauma-related cases decreasing from 14.3% to 3.9%. Hypertension (57.1%) and dyslipidemia (29.2%) prevailed post-lifting. Urgent cases decreased from 1.3% to 0.1%. This study emphasizes the importance of primary care in post-evacuation zones, addressing diverse medical needs, including trauma, noncommunicable diseases, and psychiatric disorders. Changing patient demographics require adaptable healthcare strategies and resource allocation to meet growing demands. Establishing a comprehensive health maintenance system tailored to these areas' unique challenges is crucial for future disaster recovery efforts.

Electric Grid of Japan before the Great Depression: A Comparison with Germany

Japan is one of the most successfully electrified countries in the world, but it does not have a unified national electric power grid: the country is divided into two zones with different standards for alternating current (50 and 60 Hz). To explore the root of Japan's split grid, this essay adopts technology historian Thomas Hughes’ socio-technical system frameworks and compares the history of national grid formation in Germany and Japan in the 1920s. In both countries, foresighted engineers and entrepreneurs noticed the necessity of a unified national grid—something we see from the case study of Matsunaga Yasuzaemon and Arthur Koepchen. However, government policy in Japan regarding frequency unification was inconsistent, whereas the German provincial governments set up clear visions for grid construction. Moreover, Japanese ideology of the day preferred market competition, whereas in Germany electric utilities coordinated with each other. For Germany, the 1920s heralded the beginning of a European grid, whereas Japan's bifurcated frequency standard hindered the formation of a unified national grid. And Japan's split grid can even result in the electric power system's fragility in the face of natural disasters such as the Great East Japan Earthquake of March 2011.

Changes in physical activity during the year after the Great East Japan Earthquake and future frailty in older survivors.

This study examines whether changes in physical activity (PA) during the first year after the Great East Japan Earthquake and Tsunami (2011-2012) contributed to preventing the onset of future frailty among older survivors of the disaster. This study tracked 2561 physically active Japanese survivors aged ≥ 65 years (43.6% men; mean age 72.9 years) who had completed self-administered questionnaires in 2011 and 2012. PA levels for participants were classified into four categories based on ≥23 and <23 metabolic equivalent hours/week in 2011 and 2012: "consistently low," "decreasing," "increasing," and "consistently high." Frailty was defined as a Kihon Checklist score ≥ 5, which is used in the long-term care insurance system in Japan. Hazard ratios were calculated for the onset of frailty using a Cox proportional hazards model that fitted the proportional sub-distribution hazards regression model with weights for competing risks of death. From 2012 to 2018, 283 men and 490 women developed frailty. Men with consistently high or increasing PA during the first year after the disaster had a lower risk of frailty. Furthermore, even increasing PA by walking for just 30 min/day prevented future frailty in men; however, this association between a change in PA and the decreased risk of frailty was not observed in women. Older men who remained physically active or resumed PA at an early stage and at a low intensity, even after being physically inactive owing to the disaster, were able to prevent future frailty. Geriatr Gerontol Int 2024; 24: 563-570.

Factors Associated With the Prevalence of Irritable Bowel Syndrome: The Miyagi Part of the Tohoku Medical Megabank Project Community-based Cohort Study.

The objective of this research is to examine factors related to irritable bowel syndrome (IBS) prevalence in a large population-based study. A cross-sectional study was conducted with participants in the Miyagi part of the Tohoku Medical Megabank Project Community-Based cohort study who completed the Rome II Modular Questionnaire. Multivariate odds ratios (ORs) for the presence of IBS and 95% confidence intervals (95% CIs) for the reference group were calculated for each factor. Additionally, a stratified analysis was performed by sex and age group (20-49 years, 50-64 years, and ≥ 65 years). Among 16 252 participants, 3025 (18.6%) had IBS, comprising 750 men (15.5%) and 2275 women (19.9%). Multivariate ORs for the presence of IBS decreased significantly with each year of age (OR, 0.98; 95% CI, 0.98-0.99). Moreover, compared with the reference group, ORs for the presence of IBS were significantly higher in individuals whose home was partially damaged by the Great East Japan Earthquake, those with < 16 years of education, those who spent less time walking, those with high perceived stress (1.77, 1.57-2.01), those with high psychological distress (1.58, 1.36-1.82), and those with high symptoms of depression (1.76, 1.60-1.94). In stratified analyses, a significant relationship was found between psychological factors and IBS prevalence in all sex and age groups. This large cross-sectional population-based cohort study identified several factors associated with IBS prevalence. Psychological factors were significantly associated with IBS prevalence across all age groups and sexes.

Trajectories of liver dysfunction and long-term evacuation status after the great East Japan earthquake: The Fukushima Health Management Survey

ObjectivesIn the Fukushima Health Management Survey (FHMS), the association between subsequent evacuation status, such as return and continued evacuation, and trends in liver dysfunction remains unclear. Therefore, this study evaluated this association using FHMS data through fiscal year (FY) 2018. MethodsThe 34,435 (14,063 men and 20,372 women) study participants underwent a Comprehensive Health Check, answered the Mental Health and Lifestyle Survey questionnaire in FY 2011, and were followed up until FY 2018. The participants were classified by trajectory for liver dysfunction using group-based trajectory modeling, and we examined differences in study items as of FY 2012 by each trajectory. Additionally, we divided the 13 municipalities, including evacuation zones, into partially evacuated, returnable, and difficult-to-return areas according to the lifting of evacuation orders as of FY 2018, and logistic regression modeling was used to investigate the association between long-term post-disaster evacuation status and the liver dysfunction trajectory. ResultsParticipants were classified by group-based trajectory modeling into Group 1 (continuously low prevalence rate; 62.2 %), Group 2 (improvement from high prevalence in FY2011; 10.8 %), Group 3 (like group 1 prevalence in FY2011 but increasing afterwards; 11.2 %), and Group 4 (continuously high prevalence; 15.8 %), respectively. Multivariate logistic regression modeling revealed the difficult-to-return areas and returnable areas had a higher risk of being in the Group 2, Group 3, and Group 4, compared with the partially evacuated areas. ConclusionsOur findings suggest that liver dysfunction is more likely to persist in areas where evacuation was more prolonged.

How informal water supply points using private wells worked in an emergency: A quantitative evaluation

ABSTRACT The effectiveness of an emergency water supply using private wells has been asserted theoretically but not evaluated in detail. This paper aims to consider the effectiveness and shortcomings of emergency water supply based on local wells and to support policy formulation regarding groundwater usage in the event of a disaster. In Kamisu City, Ibaraki Prefecture, Japan, not only public-operated formal water supply points using water trucks but also informal water supply points using private wells were open to address water outages following the Great East Japan Earthquake of 2011. This study clarified the pattern of appearance and spatial distribution of those points by combining information from local newspapers, Internet archives, and an original questionnaire survey. In addition, the function of informal water supply points was quantitatively evaluated using GIS by comparing cases with and without informal water supply points. Analysis revealed that informal water supply points expanded the size of the serviced population within a 500-m radius of the water supply points by 47%, compared with cases when only formal water supply points were available. However, well water was not necessarily suitable for drinking owing to quality issues. As a policy lesson, the importance of sharing well information is indicated.

Attachment and adjustment in expatriate reactions to the 2011 Tohoku disasters

PurposeThis study aims to develop an extended social attachment model for expatriates, integrating a multiple stakeholder perspective, to understand evacuation decisions during disasters.Design/methodology/approachThrough interviews with 12 Tokyo-based expatriates who experienced the 2011 Tohoku earthquake, tsunami and nuclear disasters, this study collects the lived experiences of a diverse set of expatriates. This data is analyzed abductively to map relevant evacuation factors and to propose a reaction typology.FindingsWhile the 2011 Tohoku disasters caused regional destruction and fears of nuclear fallout, Tokyo remained largely unscathed. Still, many expatriates based in Tokyo chose to leave the country. Evacuation decisions were shaped by an interplay of threat assessment, location of attachment figures and cross-cultural adjustment. The study also discusses the influence of expatriate types.Practical implicationsDisaster planning is often overlooked or designed primarily with host country nationals in mind. Expatriates often lack the disaster experience and readiness of host country nationals in disaster-prone regions in Asia and beyond, and thus might need special attention when disaster strikes. This study provides advice for how to do so.Originality/valueBy unpacking the under-researched and complex phenomenon of expatriate reactions to disasters, this study contributes to the fields of international human resource and disaster management. Specifically, seven proposition on casual links leading to expatriate evacuation are suggested, paving the way for future research.

A study on the actual conditions of reconstruction process in disaster hazard area in the affected area by the Great East Japan Earthquake

A study on the actual conditions of reconstruction process in disaster hazard area in the affected area by the Great East Japan Earthquake

Investigation of Atmospheric Anomalies due to the Great Tohoku Earthquake Disturbance Using NRLMSISE-00 Atmospheric Model Measurement

In this study, the atmospheric changes for the 9.0-magnitude Tohoku earthquake, which occurred on March 11, 2011, are analyzed. The March 11, 2011 earthquake was preceded by a large foreshock on March 09, 2011 with magnitude M 7.3 and depth 32 km at 02:45:20 UT near the east coast of Honshu, Japan. The earthquake doesn’t limit its effects on the Earth’s lithosphere, hydrosphere and biosphere; it also extends its effects to the atmosphere because of the gas emissions, which produce large-scale seismic waves from the ground and release gases into the atmosphere. In this study, the anomalies of the atmospheric parameters are studied by using one of the atmospheric models from the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Extension 2000 (NRLMSISE-00) model data to analyze the atmospheric anomalies of the Tohoku Earthquake on March 11, 2011. The atmospheric parameters of atomic oxygen (O), hydrogen (H), atomic nitrogen (N), helium (He), argon (Ar), molecular oxygen (O2), molecular nitrogen (N2), total mass density (ρ), neutral temperature (Tn), exospheric temperature (Tex) and anomalous oxygen (AO) are used for analysis during the earthquake occurrence. The epicenter of the Tohoku earthquake, with a geographical location of latitude 38.30° N and longitude 142.37° E, is used for the NRLMSISE-00 model as input parameters to analyze the output of atmospheric parameters. To compare the atmospheric changes caused by the earthquake, 5 days before and after the earthquake are considered. To detect where the atmospheric parameters increased or decreased from the earthquake day, the percentage deviation of the NRLMSISE-00 model is applied. The results indicate that there were atmospheric parameter anomalies that occurred a few days before, following and during the earthquake on March 11, 2011. Except for hydrogen (H), all atmospheric parameters average daily percentage deviation values were positive during the 5 days before and after with respect to the main earthquake shock on March 11, 2011. The NRLMSISE-00 model can capture the atmospheric parameter anomalies of the Tohoku earthquake well.

Mite allergen levels and fungal counts in children's bedding in four widely separated towns in Japan

We evaluated the relationships between children's housing, earthquake or tsunami damage affecting children, prevalence of allergic diseases, and levels of mite allergens and fungi on children's bedding after the Great East Japan Earthquake in four municipalities in Japan. We surveyed 464 children in Ishinomaki, 254 in Kami, 614 in Iwanuma, and 300 in Oiso whose parents or guardians had completed the International Study of Asthma and Allergies in Childhood questionnaire. We measured the levels of Dermatophagoides 1 allergens (Der 1) (Dermatophagoidespteronyssinus and Dermatophagoides farinae) on children's mattresses or futons and fungal counts (Aspergillus and yeast) between 2016 and 2018. Earthquake damage was significantly greater in Ishinomaki than in the other three municipalities. There were no differences in the prevalence of allergic disease among the four municipalities. Der 1 levels were significantly higher in Ishinomaki than in Iwanuma, but there were no differences among Oiso, Iwanuma, and Kami. Der 1 levels in children with asthma in Iwanuma and with allergic rhinitis in Kami were significantly higher than in those without these conditions. Total fungal counts and Aspergillus counts were highest in Kami and lowest in Oiso. Der 1 levels were significantly correlated with fungal counts in Kami and Iwanuma, but not in Ishinomaki or Oiso. Both Der 1 levels and total fungal counts in Ishinomaki were greater than those in other three municipalities. Housing and allergen-avoidance strategies varied among the four municipalities. Mite allergen and fungal levels in these Japanese municipalities might have been affected by the earthquake and tsunami, and these changes might have affected the prevalence of allergic diseases in children.

Associations Between Lifestyle Factors and Constipation Among Survivors After the Great East Japan Earthquake: A 9-year Follow-up Study.

Disaster survivors experience deterioration in lifestyles and an increase in constipation. After the Great East Japan Earthquake in 2011, some survivors were evacuated for a long term, even after moving to temporary housing and public reconstruction housing. However, annual changes in constipation and the association between lifestyles and constipation among the survivors are still unknown. Overall, 9,234 survivors aged 18 years or older participated in this 9-year follow-up survey after the disaster. Information about the prevalence of constipation and lifestyle factors (diet, physical activity, and mental health) was collected using a self-reported questionnaire. Their dietary intake was categorized into the following two dietary patterns: prudent (fish and shellfish, soybean products, vegetables, fruits, and dairy products) and meat (meat and eggs). Odds ratios for constipation according to lifestyle factors were calculated using a generalized linear mixed model. In women, the prevalence of constipation was the highest at baseline (8.7%) and remained around 5% afterward. In both men and women, older age, poor mental health, and poor physical activity were significantly associated with higher odds ratios of constipation. Moreover, a lower frequency of meals and a lower prudent dietary score were significantly associated with women's constipation. The prevalence of constipation was the highest at baseline and remained around 5% in women. Lifestyle factors, such as poor mental health, physical inactivity, and low frequency of meals were associated with constipation. Our findings suggest continuous support for the survivors with constipation for medium- to long-term after disasters.

Comparative analysis of gender and prefecture-based attitudes toward future parenthood following the Fukushima Daiichi Nuclear Power Plant accident

This study aimed to examine both concerns about future childbirth and childcare associated with radiation exposure among men and women in different prefectures. In December 2018, a cross-sectional, online questionnaire-based survey was conducted on 620 adults in the general population. The survey included 155 men and 155 women who lived in Fukushima Prefecture at the time of the Great East Japan Earthquake (March 11, 2011), and 155 men and 155 women who lived outside of Fukushima Prefecture. Regardless of gender and prefecture, the greater the perceived anxiety about radiation effects on a partner, the greater the perceived anxiety about future childbirth. In addition, those who did not want to have children were more anxious about rearing children in the future. Compared with women in other prefectures, men in Fukushima Prefecture were more knowledgeable about radiation, thought that radiation would have fewer health effects on their children, and were more confident about future childbearing. These findings suggest that for those who are anxious about future childbirth and childcare, it is important to create an environment where necessary information can be accessed regardless of gender or residence in an area affected by a nuclear accident.

Long-term mental health and resilience of the first responders in Japanese ground self-defense forces engaging body recovery after the great east Japan earthquake

Handling human remains is extremely difficult and stressful task, and it can contribute to the development of stress-related mental health problems. To prevent disaster from the development of mental disorders in first responders, it will be important to elucidate factors sustaining psychological well-being following the events requiring handling of human remains. Japanese Ground Self-Defense Forces (JGSDF) first responders (n = 146), involved in human remains recovery after the Great East Japan Earthquake (GEJE) participated. We examined the psychological resilience (S-H Resilience Test), depressive symptoms (SDS), and psychological distress (GHQ-28) 6 years after GEJE, in three groups; Group A: no contact no view of human remains, B: view only of human remains, and C: direct handling of human remains. S-H Resilience test evaluated the 3 subclasses of resilience; Social Support, Self Efficacy, Sociality. One-way ANOVA revealed the significant difference in resilience scores between Group B and C without any differences in depressive symptoms or psychological distress among the 3 groups. Multiple regression analyses revealed that depressive symptoms and resilience were associated with psychological distress in all participants. Path analyses showed that whereas one subtype of resilience indirectly reduced psychological distress through lower depressive symptoms in Group A (Social Support) and Group B (Sociality), both subtypes of resilience indirectly reduced psychological distress by lowering depressive symptoms in Group C. These findings suggest that exposure to higher stressful situation may decrease the psychological resilience based on the S-H Resilience test, and two subtypes of resilience may be necessary to sustain the psychological well-being.

Prediction and Factor Analysis of Liquefaction Ground Subsidence Based on Machine-Learning Techniques

Liquefaction is a significant challenge in the fields of earthquake risk assessment and soil dynamics, as it has the potential to cause extensive damage to buildings and infrastructure through ground failure. During the 2011 Great East Japan Earthquake, Urayasu City in the Chiba Prefecture experienced severe soil liquefaction, leading to evacuation losses due to the effect of the liquefaction on roads. Therefore, developing quantitative predictions of ground subsidence caused by liquefaction and understanding its contributing factors are imperative in preparing for potential future mega-earthquakes. This research is novel because previous research primarily focused on developing predictive models for determining the presence or absence of liquefaction, and there are few examples available of quantitative liquefaction magnitude after liquefaction has occurred. This research study extracts features from existing datasets and builds a predictive model, supplemented by factor analysis. Using the Cabinet Office of Japan’s Nankai Trough Megathrust Earthquake model, liquefaction-induced ground subsidence was designated as the dependent variable. A gradient-boosted decision-tree (GDBT) prediction model was then developed. Additionally, the Shapley additive explanations (SHAP) method was employed to analyze the contribution of each feature to the prediction results. The study found that the XGBoost model outperformed the LightGBM model in terms of predictive accuracy, with the predicted values closely aligned with the actual measurements, thereby proving its effectiveness in predicting ground subsidence due to liquefaction. Furthermore, it was demonstrated that liquefaction assessments, which were previously challenging, can now be interpreted using SHAP factors. This enables accountable wide-area prediction of liquefaction-induced ground subsidence.