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Outbreaks of infectious diseases can occur after natural disasters as vital services are disrupted and populations move into evacuation centres. National notifiable disease surveillance may be inadequate in these situations because of resource-consuming disease confirmation or system interruptions. Although syndromic surveillance has been used as an alternative in post-disaster situations, no systematic evaluations of it have been published. We evaluated the ad hoc paper-based syndromic surveillance system implemented in evacuation centres in Ibaraki prefecture after the 2011 Great East Japan Earthquake and Tsunami. We assessed the simplicity, acceptability, data quality, timeliness and portability of this system and reviewed its usefulness. We concluded that the system was simple, acceptable, portable and useful. The documentation and monitoring of disease events and trends were useful for developing interventions in evacuation centres and have since been used to improve post-disaster infectious disease and surveillance knowledge in Japan. We believe timeliness was a challenge due to the chain of data transmission and communication passing through an intermediary. Future implementations of this system could consider a more direct chain of data transmission and communication from collectors to analysers. Too few key informant interviewees and the inability to obtain original paper-based data from evacuation centres limited our findings; we conducted this evaluation four years after the response occurred. Future evaluations should be completed closer to when operations cease. The usefulness of the system suggests adopting it in future disasters. A simple, plain-language manual should be developed to improve future employment.

The electron density (Ne), ion density (Ni), and electron temperature (Te) statistics recorded by the DEMETER satellite payload ISL (Instrument Sonde de Langmuir) were used to study the disturbance characteristics of the ionosphere before solid earthquakes of magnitude 6 or higher in Japan during the summer of 2005 – 2009 , to provide more information and methods for the coupling mechanism and short-range earthquake prediction. In this paper, the region of ± 10 ° of the epicenter is divided into 1 ° × 1 ° pixels, and the background field of each parameter is constructed using data without earthquakes and relatively calm space weather. We also define a measure of the perturbation intensity of ionospheric parameters relative to the background field during the occurrence of earthquakes. The analysis results of the four Japanese earthquakes from space and time show an excellent synchronization in the time and area of the anomalies in ionospheric parameters of the four cases. All four instances showed Ne abnormalities, and three showed Ni and Te anomalies, in which N e and Ni increased or decreased abnormally, while Te increased abnormally every time, and the anomalies mainly occurred about 9–12 days before the earthquake. This paper eliminates the influence of solar, geomagnetic, and satellite data defects on the experimental results as much as possible in data screening and method selection. The results partially agree with the conclusions reported in the existing literature, and the obtained anomalies are somewhat related to the ionospheric precursors of earthquakes. [ABSTRACT FROM AUTHOR]

When discussing Buddhism in practice, we should first note that the word practice has a multilayered meaning in Buddhism. For the purposes of this paper, I would like to simplify things considerably, and divide those multiple meanings into two groups. The first involves the training of one's mind and body. By engaging in such training, the practitioner is said to draw closer to Buddhist enlightenment. This practice takes various forms depending on the time and place, such as observing the precepts or engaging in meditation, and is referred to as 'benefiting the self' (jiri 自利). Second, there is the practice that consists of Buddhists' activities vis-à-vis society. Even Buddhists, whose fundamental orientation is towards leaving the secular world (shusseken 出世 間), have engaged in activities in society that have taken a variety of forms. There are records of Śākyamuni having given various pieces of advice to rulers during ancient times. We also find many records of later Buddhists engaging in missionary and charitable activities. This is referred to as 'benefiting others' (rita 利他). In particular, Mahayana Buddhism emphasizes the inseparability of 'benefiting the self' and 'benefiting others'. Although Buddhist practice is traditionally divided into two categories: self-interest and altruism, it would not be true to say, in fact, that 'benefiting others' has always been as much of a primary concern as 'benefiting the self.' Rather, it can be said that concern for others has always been a weakness of Buddhism, overshadowed by concerns with 'benefiting the self.' Thus, Mahayana Buddhism's emphasis on the importance of benefiting others, on the contrary, could be said to imply that this was a weakness of the Buddhism at the time of the Mahayana arose. My paper focuses on recent developments surrounding Buddhism and its practice in contemporary Japan, particularly the element of 'benefiting others.' The question of how Buddhists should contribute to society has continually and repeatedly appeared from the origins of Mahayana Buddhism to the present. Against this backdrop, an event occurred in Japan in recent years that marked a major turning point in the issue of Buddhist contributions to society. That event is the Great East Japan Earthquake of 2011. In this paper, I consider the issue of 'benefiting others' in Buddhism in light of the effects of the tragic earthquake disaster. [ABSTRACT FROM AUTHOR]

Earthquake swarms are most commonly composed of small‐magnitude earthquakes. However, a recent study by Yoshida, Uchida, et al. (2023, https://doi.org/10.1029/2023GL106023) analyzed a swarm beneath the Noto Peninsula in Japan that, after more than two years of moderate‐magnitude seismicity, triggered the moment magnitude (Mw) 6.2 Suzu mainshock in May 2023. Based on high‐precision earthquake locations and a slip inversion of the mainshock, these authors found that the Mw 6.2 Suzu earthquake occurred on the updip extension of a fault that was active during the swarm, likely driven by increased fluid pressure. After publication of that paper, a much larger and more destructive Mw 7.5 event occurred nearby on 1 January 2024. These events underscore the potential for swarms to be precursors to large, damaging earthquakes. Forecasting the eventual evolution of swarms is currently very challenging but could be aided in the future by new observations and models. Plain Language Summary: Although earthquake swarms often only contain small earthquakes, occasionally they can trigger large, damaging earthquakes. Yoshida, Uchida, et al. (2023, https://doi.org/10.1029/2023GL106023) examined the triggering of a magnitude 6.2 earthquake in Japan, which caused extensive damage, following two years of smaller earthquakes. This sequence, like many swarms, may have been driven by elevated fluid pressure migrating upwards within the crust. After publication of that paper, a much larger and more destructive Mw 7.5 event occurred nearby. Forecasting the eventual evolution of ongoing swarms is currently very challenging but could be aided in the future by new observations and models. Key Points: Earthquake swarms can be precursors to damaging earthquakes, including the 1 January 2024, Mw 7.5 Noto Peninsula, Japan eventFluid pressure changes often drive swarm activity, and their degree of confinement may influence swarm evolutionDirect observations of fluids in fault zones combined with numerical modeling may aid swarm forecasting in the future [ABSTRACT FROM AUTHOR]

Kyushu Shinkansen and conventional railway lines run parallel in the areas 5 km north of Kumamoto Station (northern area) and 12 km south of the station (southern area). Following the operation of the Kyushu Shinkansen Line in 2011, the adjacent conventional railway line in the north was elevated, a new station was operated in the south, and large earthquakes struck the Kumamoto area from March to April 2016. Sleep disturbances were compared before and after the interventions and earthquakes based on noise source (Shinkansen and conventional railways), area (northern and southern), and house type (detached and apartment) through socio-acoustic surveys from 2011 to 2017. The Shinkansen railway caused significantly less sleep disturbances in detached houses in the north after compared to before the earthquakes, presumably due to more frequent closures of bedroom windows in northern detached houses following the earthquakes. The Shinkansen railway caused significantly more sleep disturbances in apartments in the south after compared to before the earthquakes, presumably because the Shinkansen slowed down immediately after the earthquakes and returned to normal speed during the survey, suddenly increasing the noise exposure. There was no significant difference in the other six cases investigated. Overall, the interventions may not have caused significant differences in sleep disturbances. This article expands on the congress paper by Morihara et al. presented in the "Community Response to Noise" session at the 52nd International Congress and Exhibition on Noise Control Engineering in Makuhari, Japan, organized by the International Institute of Noise Control Engineering.

In this study, we aimed to assess the capacity of a physics-based earthquake simulator to improve our understanding of the seismogenic process. In this respect, we applied a previously tested earthquake simulator to two well-known and completely different seismogenic fault systems, namely the Italian Apennines and the Nankai subduction in Japan, for which long historical records of strong earthquakes are available. They are characterized by different fault mechanisms, fault sizes, and slip rates. Because of the difference in slip rates, the time scale of the seismicity patterns is different for the two systems (several hundreds of years for the Apennines and a few tens of years for the Nankai Fault). The results of simulations that produced synthetic catalogues of 100,000 years show these significant long-term seismicity patterns characterizing the seismic cycles for both seismogenic areas as follows: The average stress and the occurrence rate of earthquakes increase in the long term as the next major earthquake approaches; while the average stress increases uniformly, the occurrence rate stops increasing well in advance of the mainshocks; the b-value exhibits a long-term increase before major earthquakes and a fast decrease shortly before the mainshocks. Even if no specific statistical tool was applied for the quantification of the similarities between the seismicity patterns of the two seismic areas, such similarities are clearly justified by the large number of seismic cycles included in the 100,000-year synthetic catalogues. The paper includes a discussion on the capability of the simulation algorithm to reliably represent the real long-term seismogenic process. This question is difficult to answer because the available historical observations are of too short a duration to provide significant statistical results. In spite of the limitations characterizing the use of earthquake simulators for time-dependent earthquake hazard assessment, and the lack of convincing mechanistic explanations of the specific seismic patterns reproduced by our simulator algorithm, our results encourage further investigations into the application of simulators for the development of seismogenic models, including short-term features. [ABSTRACT FROM AUTHOR]

Recent geodetic measurements have detected recurrent slow slip events (SSEs) in many subduction zones. Numerical simulations suggest that the recurrence intervals and magnitudes of such SSEs decrease in the later stage of the interseismic period. Therefore, activities of SSEs and their temporal variations in recurrence intervals and magnitudes provide important clues for evaluating future large earthquakes. However, our knowledge of recurrent SSEs before the establishment of dense observation networks is limited. Here, we report a possible SSE in 1973 beneath the Kii peninsula along the Nankai subduction zone, southwest Japan, where magnitude 8 class earthquakes such as the 1944 Tonankai and 1946 Nankai earthquakes repeatedly occur. The possible SSE was detected by a horizontal pendulum tiltmeter installed in 1947 at the Kishu observatory. We recovered and converted the original tilt records from 1969 to 1974 drawn on bromide (light sensitive) papers to digital tilt records. In late-November 1973, there was a slow transient signal down to the northeast of about 1.4 μrad, lasting about 1–3 days. Assuming this crustal deformation was due to an SSE, we searched for a possible fault model by adopting the already-known SSE models occurring from 1996 to 2012 as template models. Among the 42 template fault models, five models were able to qualitatively explain the direction of the observed tilt change. The centroids of these fault models were located about 30–60 km to the west of the observatory. In the source region, two magnitude 5 class earthquakes occurred before the initiation of the transient signal, and thus may be related to the occurrence of the possible SSE. In contrast, the magnitude of the calculated tilt change was about 1–2 order smaller than that of the observed tilt change. This discrepancy could be partly explained by a slip amount larger than that in the template models, which suggests that the possible SSE in 1973 was larger than those detected by recent observations. Further investigation of historical data on crustal deformation will reveal more about the temporal change in the recurrence intervals and magnitudes of SSEs during earthquake cycles of large earthquakes. [ABSTRACT FROM AUTHOR]

The year 2023 marks the 100th commemoration of the disastrous Kanto Earthquake in Japan, which shattered the urban fabric of Tokyo and other southern prefectures. In the years following 1923, much research into disaster risk reduction (especially fire prevention) was undertaken. This study evaluated research trends and the impact of the earthquake on the city using metropolitan population data. The following is reported: (1) This study summarized English and Japanese academic papers and reports on the Great Kanto Earthquake that have been published over the last 100 years. (2) The area of fire spread and number of damaged buildings in Tokyo due to the Great Kanto Earthquake were overwhelmingly larger than those in other areas. (3) The difference in the relative amount of damage caused by natural disasters with more than 1,000 death toll to the annual national budget in Japan became clear. (4) The Great Kanto Earthquake was the only natural disaster that caused a net worth of damage exceeding the Japanese national budget by 3.8 times. (5) The expansion of the Tokyo metropolitan area over the 100 years since the Great Kanto Earthquake was visually clarified based on demographics. (6) Today, many people live densely on soft ground, with an amplification factor of 1.8 or higher, which is 23.0% of the total population. [ABSTRACT FROM AUTHOR]

Background. The significance of mutual-help in communities for disaster management is a fundamental important concept. However, the current societal state does not reflect this lesson. S&G (Simulation and Gaming) has the potential to overcome the challenges faced in promoting community-based disaster management. No scientific research is currently present that reviews their achievements in Japan. Aim. This paper analyzes the current achievements of S&G in enhancing community resilience against large-scale earthquakes in Japan. Method. The paper clarifies the theoretical advantages of S&G in enhancing community resilience in coping and adaptive capacity plus proposes a conceptual contribution framework of S&G in improving community resilience. Based on this framework, the paper analyzes some major games that tackle community resilience against earthquakes in Japan. Results. The paper demonstrates the achievements through the S&G spectrum that stresses the disastrous experience with specific resilience views on one side, while decision making for critical reflection from other players with more comprehensive resilience views on the other side. Conclusion. The paper showcases the current S&G achievements in enhancing community resilience against large-scale earthquakes in Japan using the proposed framework, which can be utilized by other disaster-prone countries to develop and evaluate applications of S&G for increasing community resilience against earthquakes. [ABSTRACT FROM AUTHOR]

The Fukushima power station in Japan was affected by a major earthquake and tsunami in March 2011, inspecting the primary containment vessel remains difficult due to high radioactivity. Long-reach robot arms are useful in inspecting such hazardous environments, and a coupled tendon-driven mechanism enables realizing a long, light-weight, and thin manipulator. However, high elastic elongation of tendons due to gravity may lead to unstable joint control. In this paper, we introduce dynamics-based control as a feasible strategy for a long-reach tendon-driven robotic arm. Additionally, a planning method to identify the joint angle path ensuring stability is proposed. Considering stability analysis, the potential due to the tendon elasticity and gravity is evaluated and used as an index of joint stability. The rapidly exploring random tree is used as the planning algorithm. The effectiveness of the proposed method was demonstrated through the successful manipulation of a 5-kg payload by a 10-m long robotic arm. [ABSTRACT FROM AUTHOR]

Disaster resilience is an interdisciplinary area of study. Collaboration between humanities and sciences is important to approach issues in this area. However, science and engineering consider disaster resilience as minimizing the scientifically estimated damage induced by natural hazards. In contrast, disaster resilience studies in the social sciences tend to focus on societal vulnerability. The views between the two disciplines can lead to inconsistency or contradiction. This paper discussed this issue. To do so, the author uses the case study focusing on the effects of predictions on Nankai Trough Earthquake countermeasures in Kochi City, Japan. First, this study revealed that not only the revision of hazard prediction but the historical background of land use development affected the large-scale earthquake damage estimation in Kochi City. Second, the upward revision of hazard prediction resulted in strengthening of community disaster management. However, it also accelerated residential relocation associated with class disparities. As a result, ironically, marginalized social groups were unevenly located in predicted tsunami inundation areas. However, such issues are not considered in the existing disaster resilience scheme and policy. Based on this analysis, it is argued that communicating scientific knowledge on hazards to society alone is not enough. Considering the local context, the perspective of literacy for disaster resilience from downstream' is also important. [ABSTRACT FROM AUTHOR]

The Great East Japan Earthquake that occurred on March 11, 2011, was one of the largest natural disasters in modern times. Publication in medical journals is important aspects of the academic promotion process, and is thus important for all scientists. However, little is known about whether and how substantial natural disasters affect gender disparities in academic productivity in disaster-affected areas. We hypothesized that the Great East Japan Earthquake widened the existing disparities in scientific publishing between male and female researchers. To test this hypothesis, this retrospective observational study using existing databases was conducted. We extracted from the MEDLINE database all types of biomedical articles published from March 11, 2007, to March 11, 2015, by three medical universities in a disaster-affected area of Japan. Differences in the proportion of female first authorship during the 4 years before and after the Great East Japan Earthquake were compared. A total of 5,873 papers were analyzed. The proportion of female first authors significantly declined after the Great East Japan Earthquake (20.5% vs. 14.1%; odds ratio 0.64; 95% confidence interval 0.56-0.73). A similar trend was identified across all prespecified subgroups, including clinical department; original article; public medical university; and prestigious journal with impact factor >6. Reference data from two medical universities minimally affected by the Great East Japan Earthquake showed the opposite trend. These results collectively suggest that large natural disasters can reinforce existing gender disparities in first authorship in biomedicine.

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., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Inoue et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

This paper discusses the relationship between the vertical ground motion and ionospheric disturbances before the Kumamoto earthquake on 16 April 2016, in Kyushu, Japan, using the vertical ground motion measured by slant gauges widely distributed in Kyushu, and the NmF2 observed by ionosondes in Japan and another region. We provide evidence that vertical ground motion excites internal gravity waves (IGWs) that disturb changes in the ionospheric plasma density. From the spectral analysis results of the vertical ground motion data, the summation of various period (frequency) components analyzed from the original data of the slant gauge shows a possible correlation with the change of NmF2 before the earthquake. On the other hand, the influence of the geomagnetic disturbance on vertical ground motion seems to exist. However, we cannot confirm that vertical ground motion is influenced by the geomagnetic disturbance (Kp index) and that the earthquake is triggered by the geomagnetic disturbance. There are two conditions for the vertical ground motion to disturb variations in the ionospheric plasma density: (1) The effective vertical ground motion period should be shorter than 5 h. In addition, (2) vertical ground motion should continue to exist so that wave energy can be continuously injected into the atmosphere. A possible mechanism with which to modify the ionosphere is discussed. The results of this study can provide a basis for the future ionospheric precursors of earthquakes by using the vertical ground motion. [ABSTRACT FROM AUTHOR]

In this paper, we explore the use of seismicity data on a single-station basis in site response characterization. We train a supervised deep-learning model, SeismAmp, to recognize and separate seismic site response with reference to seismological bedrock (VS  = 3.45 km s−1) in a broad frequency range (0.2–20 Hz) directly from single-station earthquake recordings (features) in Japan. Ground-truth data are homogeneously created using a classical multistation approach—generalized spectral inversion at a total number of 1725 sites. We demonstrate that site response can be reliably separated from single-station seismograms in an end-to-end approach. When SeismAmp is tested at new sites in both Japan (in-domain) and Europe (cross-domain), it achieves the lowest standard deviation among all tested single-station techniques. We also find that horizontal-to-vertical spectral ratio (HVSR) is not the optimal use of single-station recordings. The individual components of each record carry salient information on site response, especially at high frequencies. However, part of the information is lost in HVSR. SeismAmp could lead to improved site-specific earthquake hazard prediction in cases where recordings are available or can be collected at target sites. It is also a convenient tool to remove repeatable site effects from ground motions, which may benefit other applications, for example, improving the retrieval of seismic source parameters. Finally, SeismAmp is trained on data from Japan, future studies could explore transfer learning for practical applications in other regions. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of 10 years of research on models of the megathrust earthquake cycles and crustal deformation associated with the 2011 Tohoku-oki earthquake. Several earthquake cycle models have been proposed for the northeast Japan subduction zone to elucidate why megathrust earthquakes occur at intervals of approximately 600 years and why large slips occurred in the shallow subduction zone. A model that considers a strong asperity in the shallow plate interface, and a hierarchical asperity model that considers the scale dependence of the critical displacement of the rate- and state-dependent friction law have been proposed. Modeling with dynamic weakening of faults has also been proposed. In the model using the shallow friction characteristics obtained by the Japan Trench Fast Drilling Project, rupture from depth can propagate to the trench, resulting in shallow large slips. Submarine crustal deformation has been observed for the first time in addition to dense observations of the inland crustal deformation. The observation of the seafloor deformation near the trench showed that viscoelastic relaxation played an important role in short-term postseismic deformation near the trench. The effects of the low-viscosity region at the oceanic lithosphere and asthenosphere boundary, and the cold forearc mantle wedge (cold nose) have been discussed. Simulations using the nonlinear flow law of rock in the mantle, where a power–law relationship holds between stress and strain rate, and the fault friction law at the plate boundary, show that the Tohoku-oki earthquake caused large stress fluctuations, resulting in a sudden viscosity decrease and rapid flow in the asthenosphere below the oceanic lithosphere. The simulations of the crustal deformation associated with the Tohoku-oki earthquake cycle also indicate that in the later stage of the earthquake cycle, the Pacific coastal region begins to subside due to the increasing slip deficit rate on the deeper parts of the plate interface. These results explain the subsidence of the Pacific coast of northeast Japan observed for about 100 years prior to the Tohoku-oki earthquake. In the future, a model that explains the long-term crust and mantle deformation during the entire Tohoku-oki earthquake cycle must be constructed. [ABSTRACT FROM AUTHOR]

Peak ground acceleration (PGA) is a key parameter used in earthquake early warning systems to measure the ground motion strength and initiate emergency protocols at major projects. The traditional P -wave peak displacement-dependent PGA prediction model (Pd-PGA model) tends to underestimate the PGA for large earthquakes because it cannot make full use of the fault continuity rupture information hidden in the time-varying process of ground motion. In this paper, a continuous PGA prediction long short-term memory (LSTM) neural network model is proposed. The model takes eight sequential features of stations that are proxies of the energy and other physical parameters as input and provides the recorded PGA at the station as the target output. A total of 5961 records from 119 earthquakes recorded by the Japanese Strong-Motion Earthquake Network (K-NET) in Japan are used to train the neural network and 3433 records from 73 earthquakes are used as the test set to verify the model's generalization ability. The results show that within the same data set, the residuals of the predicted PGA for the proposed model are smaller than those of the Pd-PGA model and that the problem of PGA underestimation is resolved. The prediction accuracy also improves with increasing sequence length, which indicates that the LSTM neural network learns the rules hidden in the time series. To further verify the model's generalization ability, the model performance is analyzed for an M 7.3 earthquake that was not included in the training or test data sets. The results show that the residuals of the predicted PGA for the event are consistent with those for the test data set, indicating that the model has good generalization ability. [ABSTRACT FROM AUTHOR]

Understanding the location of risk to natural hazards, namely the areas of high exposure and vulnerability is a major priority that was identified by the Sendai framework for Disaster Reduction 2015-2030 in order to reach substantial reduction of disaster risk. It is also a necessary decision-making tool for disaster mitigation policy-makers in Japan and around the world. This paper successfully develops a simple methodology using only open data to build the first large-scale (whole country), fine resolution (sub-municipal level) social vulnerability analysis in the context of five different types of natural hazards (earthquake, tsunami, storm surge, flooding and landslide). The result is then compared to an indicator of exposure of population to these hazards in Japan in order to propose a representation of disaster risk. Results show that vulnerability in Japan is highly heterogeneous with urban/rural and north/south fractures. Combining the social vulnerability index with exposure analysis, results show a wide variety of spatial patterns of risk areas in Japan., (© 2023. The Author(s).)

Background: Health-beneficial emergency bedding has become increasingly important for dealing with natural disasters such as the anticipated Nankai Trough earthquake in Japan. When the Great East Japan Earthquake occurred, cardboard beds were provided to evacuees. However, there were concerns about lower back pain and sleep disturbances, as cardboard beds offer insufficient pressure distribution. This study aimed to compare the effects of cardboard beds with those of foldable camp cots on sleep quality. Methods: A randomized controlled crossover study involving 20 healthy participants aged 18–45 years was conducted between June 2022 and January 2023. Participants were asked to sleep for one night on a camp cot and for another night on a cardboard bed, with a minimum three-day washout period between the two nights. Body pressure distribution and sleep metrics obtained from polysomnography (PSG) and questionnaires were compared between the two-bed types (P < 0.05). Results: The camp cot exhibited better body pressure distribution than a cardboard bed, leading to improved sleep satisfaction, bedding comfort, and reduced morning sleepiness. Nevertheless, polysomnography revealed no notable differences in sleep metrics or sleep architecture between the two types of beds. Conclusions: Our findings indicate that cardboard beds have lower pressure dispersion capabilities than camp cots, leading to an increased number of position changes during sleep. Additionally, subjective sleep quality, such as alertness on waking, sleep comfort, and sleep satisfaction, was lower for cardboard beds, suggesting that camp cots might offer a more comfortable bedding option for evacuees. However, there were no discernible differences between the two-bed types in terms of objective sleep metrics derived from PSG. The potential for sleep disturbances caused by lower back pain from a hard mattress has been noted, and it is possible that a single night's experience in healthy individuals might not be enough for sleep issues to manifest. [ABSTRACT FROM AUTHOR]

Shikoku island, southwestern Japan lies in the western Nankai Trough and showcases along-strike segmentation of slow earthquake behavior. Whether the spatial variation of tremor behavior reflects the regional differences in structure/source properties and how much such differences can be recognized by the seismic signals themselves are two questions addressed in this paper. Taking advantage of advanced methods in recognizing and classifying signals using machine learning approaches, we attempt to answer them by conducting signal classification experiments in Shikoku. Based on the tremor catalog from 1 June 2014 to 31 March 2015, the tremors recorded in four different areas were treated as different classes and segmented into 60-s-long signals. The number of tremors in four different areas (A to D, from west to east) reached 15,000, 31,000, 10,000, and 16,000, respectively. To efficiently distinguish between tremors from different areas, we applied a k-nearest neighbor (k-NN) classifier with Fisher's class separability criteria to select the optimal feature subset. The resulting classification performance reached more than 90% at all 12 stations. We further designed a triangle test to select the features that can better represent the differences in source properties between areas. We found that the most efficient features were associated with (1) the number of peaks in the temporal evolution of discrete Fourier transforms and (2) the energy distribution in the autocorrelation function (ACF). To match the difference in behavior revealed by the ACF, the size of the tremor zone, which mainly controls how long the seismic energy lasts in a tremor episode, was determined to be largest in Area B and smallest in Area C. The heterogeneity of the asperities in a tremor zone, which may control how spiky the tremor signals developed over time, was determined to be strong in Areas B and C. Together with previously documented variations in slow earthquake behavior in the same area, we finally propose a conceptual model that provides a better understanding of the regional differences in the tremor source properties in Shikoku, Japan. [ABSTRACT FROM AUTHOR]

This paper presents a rapid or real-time estimation method of the economic value of direct stock damages caused by significant earthquakes in Japan. The result will contribute to both the government and private sectors' early decision-making, particularly for provisional budget allocation. First, we developed a simple but evidence-based model for estimating stock losses explained by a representative earthquake hazard factor and an exposure factor, i.e., seismic intensity and existing stock of physical assets. The key characteristic of our estimation model is that the dependent variable is prefectural damage amount. Still, the explanatory variables come from municipal sources: we overcome this data availability problem through our estimation process. Second, we carefully checked the model's specification, estimation, and performance to be soundly applied to a real-time assessment of future earthquake events. We also explain the automated measuring of the prefectural direct loss value and its distribution to every 250 m mesh. Finally, we show two examples of the application of our model; one is the case of the 2018 Northern Osaka Earthquake, and the other is the anticipated Tokyo inland earthquake. [ABSTRACT FROM AUTHOR]

Slow earthquakes are episodic slow fault slips. They form a fundamental component of interplate deformation processes, along with fast, regular earthquakes. Recent seismological and geodetic observations have revealed detailed slow earthquake activity along the Japan Trench—the subduction zone where the March 11, 2011, moment magnitude (Mw) 9.0 Tohoku-Oki earthquake occurred. In this paper, we review observational, experimental, and simulation studies on slow earthquakes along the Japan Trench and their research history. By compiling the observations of slow earthquakes (e.g., tectonic tremors, very-low-frequency earthquakes, and slow slip events) and related fault slip phenomena (e.g., small repeating earthquakes, earthquake swarms, and foreshocks of large interplate earthquakes), we present an integrated slow earthquake distribution along the Japan Trench. Slow and megathrust earthquakes are spatially complementary in distribution, and slow earthquakes sometimes trigger fast earthquakes in their vicinities. An approximately 200-km-long along-strike gap of seismic slow earthquakes (i.e., tectonic tremors and very-low-frequency earthquakes) corresponds with the huge interplate locked zone of the central Japan Trench. The Mw 9.0 Tohoku-Oki earthquake ruptured this locked zone, but the rupture terminated without propagating deep into the slow-earthquake-genic regions in the northern and southern Japan Trench. Slow earthquakes are involved in both the rupture initiation and termination processes of megathrust earthquakes in the Japan Trench. We then compared the integrated slow earthquake distribution with the crustal structure of the Japan Trench (e.g., interplate sedimentary units, subducting seamounts, petit-spot volcanoes, horst and graben structures, residual gravity, seismic velocity structure, and plate boundary reflection intensity) and described the geological environment of the slow-earthquake-genic regions (e.g., water sources, pressure–temperature conditions, and metamorphism). The integrated slow earthquake distribution enabled us to comprehensively discuss the role of slow earthquakes in the occurrence process of the Tohoku-Oki earthquake. The correspondences of the slow earthquake distribution with the crustal structure and geological environment provide insights into the slow-earthquake-genesis in the Japan Trench and imply that highly overpressured fluids are key to understanding the complex slow earthquake distribution. Furthermore, we propose that detailed monitoring of slow earthquake activity can improve the forecasts of interplate seismicity along the Japan Trench. [ABSTRACT FROM AUTHOR]

In Japan, natural disasters have historically caused massive damage, and the importance of emergency temporary housing is increasing. In this paper, the summer thermal environment at the Shirahata temporary housing site in Kousa Town was assessed. The site was constructed following the 2016 Kumamoto Earthquake. The site was improved by applying a design methodology called "Kumamoto Type D," "D" stands for "Default & Design." Field measurements and computational fluid dynamics simulations were conducted to investigate the influence of the building arrangement on the outdoor thermal environment for the Kumamoto Type D layout. The results indicated that the impact of wind was reduced using this layout. However, when the surface temperature in the parking lot and other areas increased, hot air could be transmitted to the site, even under reduced wind conditions. [ABSTRACT FROM AUTHOR]

Japan has an established tradition of museums commemorating its long history of disasters, which memorialize lives lost and convey the scientific mechanisms of natural hazards, disaster history, and people's experiences during and after disasters. The first part of this paper provides an overview of seven modern disaster museums in Japan established before 3.11, starting from the museum of the 1923 Great Kanto Earthquake. These seven museums commemorate disasters of different types, time, and scales of damages. Considering their shared commonalities and individual characteristics, it describes the components and approaches of exhibits that these museums use to convey experiences and stories of disasters, passing on local knowledge toward future disaster risk reduction. The second part of the paper provides an overview of new museums and exhibit facilities established to commemorate the 3.11 Great East Japan Earthquake, tsunami, and nuclear disaster of March 11, 2011. The scale of the devastation of 3.11, as well as an explosion of interest and support for activities of memorialization, documentation, and exhibition, has resulted in a variety and decentralization of new museums and exhibit spaces throughout the area affected by the 3.11 disaster. Spanning various combinations and types of exhibit facilities, this paper concludes by considering emergent trends compared to pre-3.11 disaster museums and potential future developments. [ABSTRACT FROM AUTHOR]

Coastal regions around the Pacific Ring of Fire share the risk of massive earthquakes and tsunamis. Along with their own political-economic, cultural and biophysical contexts, each region has their own history and experiences of tsunami disasters. Coastal areas of Washington State in the U.S. are currently at risk of experiencing a tsunami following a massive Magnitude 9 (M9) earthquake anticipated in the Cascadia Subduction Zone (CSZ). Looking ahead to consider adaptive planning in advance of a tsunami following this M9 event, this paper explores how lessons from recent megaquake- and tsunami-related experiences of risk-based planning and relocation in coastal areas of Japan and Chile could inform anticipatory action in coastal Washington State. Based on a comparison of earthquake and tsunami hazards, social factors, and the roles of government, this paper outlines a framework to compare policy contexts of tsunami risk-based planning and relocation in three Ring of Fire countries, including factors shaping the possible transfer of approaches between them. Findings suggest some aspects of comparative significance and commonalities shared across coastal communities in the three countries and at the same time highlight numerous differences in governance and policies related to planning and relocation. Although there are limitations to the transferability of lessons in disaster adaptive planning and anticipatory action from one national/regional context to another, we believe there is much more that Washington and the Pacific Northwest can learn from Japanese and Chilean experiences. In any context, risk reduction policies and actions need to garner political support in order to be implemented. Additional case study research and detailed analysis is still needed to understand specific lessons that may be applied to detailed risk-based planning and relocation programs across these different national contexts. [ABSTRACT FROM AUTHOR]

Crustal earthquakes are generally recognized as having recurrence periods of more than 1000 years. However, in northern Ibaraki Prefecture, Japan, two moderate-sized earthquakes occurred on almost the same fault plane in 2011 and 2016. Moreover, it has been reported that the slip distributions derived from crustal deformation data from these two events are almost identical. We performed a near-field waveform inversion analysis to estimate the details of the spatiotemporal distribution of the co-seismic rupture. Our results reveal large slip areas during each earthquake at different locations across the bend of the fault plane. These results indicate that the shear stress of the fault area where the main slip occurred during the 2011 event was not rebuilt in such a short period, a phenomenon that had not previously been discussed for this sequence. Our results also suggest that the fault geometry affected such complex fault ruptures. [ABSTRACT FROM AUTHOR]

Since huge earthquakes are expected along plate subduction zones such as the Japan Trench and Nankai Trough, the estimation of coseismic slip and interseismic slip deficit is essential for immediate response and preliminary measures to reduce damage. Recently, analysis considering the complex topography and underground structure of the plate subduction zone has been performed for improving the estimation performance. However, the three-dimensional (3D) crustal structural model needs to be improved continuously. In this paper, we obtained Green's functions for 3D crustal structural models with ambiguity by 3D crustal deformation analysis, and the coseismic slip and interseismic slip deficit were estimated. Here we enabled the calculation of many Green's functions with different physical properties of the 3D crustal structure by utilizing a GPU-based 3D crustal deformation analysis method that significantly reduces the analysis cost. The physical properties on the upper plate's side, which are located above the plate boundary fault, were changed. We found no significant difference in the estimation performance, except for the upper crust, which most of the fault slip area is in contact with, in the case of coseismic slip estimation. In contrast, the coseismic slip estimation when the properties of the upper crust was changed had a significant error, and a negative slip was estimated at the deep part of the plate boundary where no slip was originally given. [ABSTRACT FROM AUTHOR]

Since the appearance and evolution of earthquake ionospheric precursors are expected to show a nonlinear and complex behaviour, the use of nonlinear predictor models seems more appropriate. This paper proposes a new approach based on deep learning as a powerful tool for extracting the nonlinear patterns from a time series of ionospheric precursors. A Long Short-Term Memory (LSTM) network as a type of Recurrent Neural Network (RNN) was used to investigate 52 six-month time series, deduced from the three Swarm satellite (Alpha (A), Bravo (B) and Charlie (C)) measurements, including electron density (Ne), electron temperature (Te), magnetic scalar and vector (X, Y, Z) components, Slant and Vertical Total Electron Content (STEC and VTEC), for day and night periods around the time and location of a seismic event. This new approach was tested on a strong Mw = 7.1 earthquake in Japan on 13 February 2021, at 14:07:50 UTC by comparing the results with two implemented methods, i.e., Median and LSTM methods. Furthermore, clear anomalies are seen by a voting classification method 1, 6, 8, 13, 31 and 32 days before the earthquake. A comparison with atmospheric data investigation is further provided, supporting the lithosphere–atmosphere–ionosphere coupling (LAIC) mechanism as a suitable theory to explain the alteration of upper geolayers in the earthquake preparation phase. In other words, using multi-method and multi-precursor analysis applied to 52 time series and also to the orbit-by-orbit investigation, the observed anomalies on the previous day and up to 32 days before the event in normal solar and quiet geomagnetic conditions could be considered as a striking hint of the forthcoming Japan earthquake. [ABSTRACT FROM AUTHOR]

This paper estimates the impact of the tsunami caused by the Great East Japan earthquake on land appraisals of various locations outside of directly damaged areas. The focus is on locations that are expected to be extensively damaged by a tsunami if the Nankai Trough earthquake occurs. We use the DID and DDD approaches and show that locations with low elevation and close to the sea experienced decreases in appraised land prices compared to locations with high elevation and far from the sea. Especially, locations with less than 3.6m elevation and within 1.46km of the coastline experienced significant decreases in appraised land prices. This result implies that people have changed their location preferences regarding elevation and distance from the sea., Competing Interests: The authors have declared that no competing interests exist.

If the Nankai Megathrust Earthquake should occur, it is clear that the disaster would become a national catastrophe. To avoid the decline of Japan caused by such earthquake first of all the proactive measures, improvement of prevention, and the reactive ones, strengthening of recovery, have to be taken by means of Disaster Resilience. Looking back on the history of Japan, we can easily understand that Japan is a lucky country, because it has never experienced the disturbances of war or huge disaster leading to a collapse of the country. However, it has become obvious that if the Nankai Megathrust Earthquake should occur, it would trigger the decline of Japan. Therefore, the Ministry of Disaster Management should be established to prevent a disaster as national catastrophe and collapse of the country. For this reason the main objectives and responses of the Ministry of Disaster Management are clarified in this paper. Especially in the phases of initial response and life rebuilding making use of the experiences of the 2016 Kumamoto Earthquake and recognizing that the Tokai Earthquake cannot be predicted, the issuance of the emergency information of the Nankai Megathrust Earthquake and its problems are discussed and summarized. [ABSTRACT FROM AUTHOR]

Techniques for quickly and easily estimating widearea damage are required to support various activities for reducing damage in the event of a large earthquake. In this paper, using a wide-area evacuation simulator, we estimate property damage and human casualties in 32 densely built-up wooden residential areas in Tokyo, assuming a large earthquake. Furthermore, the relationships among local urban environment, property damage, and human casualties are analyzed using multiple regression analysis. [ABSTRACT FROM AUTHOR]

To improve the accessibility of emergency vehicles after a large earthquake, it is important to quantify the effects of risk mitigation strategies. In this paper, using a simulation model that describes the movement of emergency vehicles amidst property collapse after a large earthquake, we evaluate street network accessibility in the Tokyo Metropolitan Area. Moreover, by analyzing the relationships between local environments and street network accessibility, we discuss the effects of riskmitigation strategies on improving street network accessibility. [ABSTRACT FROM AUTHOR]

This paper describes the development and present status of seismic evaluation and seismic retrofit of existing buildings mainly for low-rise and medium-rise reinforced concrete buildings in Japan. First, since the seismic evaluation of existing buildings has close relationships with the seismic design of new buildings, a brief history of the development of seismic design, seismic evaluation, and seismic retrofit is provided in terms of major earthquake disasters mostly in Japan and associated with some major events in the U.S. Then, the development of seismic evaluation and retrofit is reviewed, focusing on the items in which the author has been deeply involved. This provides insight into previous earthquake damage, methodologies for seismic evaluation, the basic concept of the Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings, studies on the demand criteria for seismic safety, and the present status of seismic evaluation and retrofit. Finally, the typical methods of seismic retrofit and some examples of retrofitted buildings in Japan are explained.

The construction of nuclear power plants in China has proceeded rapidly in recent years, and a nuclear power plant cluster is present in the coastal area of Fujian Province. Considering the lessons of the Fukushima Daiichi nuclear power plant accident, we applied the Monte Carlo approach to calculate the correlation characteristics of earthquake impacts on the nuclear power plant cluster and to assess the seismic hazards at multiple sites. Based on the seismic source zone model, seismicity model and ground-motion prediction model of the Seismic Ground Motion Parameters Zonation Map of China, many earthquake scenarios were sampled, and the possibility of multiple sites experiencing ground motions that exceed critical values at the same time were obtained. The results show that the correlation between nuclear power plants Fuqing (C) and Putian (D) is the largest and that they have a slight probability of exceeding their respective design criteria at the same time. The correlation of earthquake impacts on nuclear power plants Ningde (A) and Xiapu (B) is also high, but the probability that they simultaneously exceed their respective design criteria is very low. This study can provide a reference for the site selection of nuclear power plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

The phenomenon named kodokushi , meaning death alone without the care or company of anyone inside temporary housing, appeared after the Kobe earthquake in Japan in 1995 with some 250 cases. This paper analyzes the evolution of Japanese temporary houses-to attempt to prevent the problem of kodokushi -from the point of view of management, how services and activities are organized, and design. We will use case studies as our methodological tool, analyzing the responses in 1995 Kobe (50,000 THs), 2004 Chūetsu (3000 THs), 2011 Tōhoku (50,000 THs), and 2016 Kumamoto (4000 THs). This article shows how the Japanese THAs follow a single design that has undergone very little variation in the last 25 years, a design which promotes the social isolation of their residents, making recovery-from the psychological perspective-and helping the most vulnerable members of society, more difficult. In small scale disasters (Chūetsu) applying organization and management measures was able to correct the problems caused by design and there were no cases of kodokushi : in large-scale disasters (Tōhoku), however, the difficulties to implement the same measures resulted in the reappearance of new cases at rates similar to Kobe's. Our main conclusion is that the design of Japanese THAs must be reconsidered and changed to respond to the real needs of the most vulnerable groups., Competing Interests: The authors declare no conflict of interest.

Purpose The purpose of this paper is to provide quantitative evidence of natural disasters’ (NDs) effect on corporate performance and studies the mechanisms through which the supply chain moderates and mediates the link.Design/methodology/approach Using two major NDs as quasi-experiment, namely the 2011 Japanese earthquake-tsunami (JET) and Thai flood (TF), and data over the period 2010Q1-2013Q4, effect of these events on end assemblers’ performance is studied, with a focus on the personal computer (PC) supply chain. The moderating influence of delivery and sourcing – as supply chain flexibility and agility – are examined through end assemblers’ and suppliers’ inventory. The suppliers’ mediating role is captured as disruption in obtaining PC components through their sales.Findings Only JET had any negative effect, further quantified as short-term and long-term. The TF instead portrays an insignificant but positive aftermath, which is construed as showing learning from experience and adaptability following JET. Inventory matters, but differently for the two events, and suppliers only exhibit a moderating influence on the assemblers’ disaster-performance link.Originality/value NDs, as catastrophic vulnerabilities, are distinct from other vulnerabilities in that they are hard to predict and have significant impact. Since little is known about the impact of NDs on firm performance and how supply chain mechanisms moderate or mediate their impact, they should be distinctly modelled and empirically studied from other vulnerabilities. This paper sheds light on supply chain resilience to such events with the role of dynamic capabilities. [ABSTRACT FROM AUTHOR]

This paper describes an efficient approach to high-resolution time-reversal source imaging simulation. Dense seismograph network records are backpropagated from stations to the hypocentre through a 3-D subsurface structure model to estimate the initial source wavefield at the earthquake initiation time. By assimilating high-density observational data into the time-reversal wave propagation, a clearer source image can be determined, even for deep and distant earthquakes, than is achievable with conventional source imaging. The effectiveness of data-assimilation-based source imaging by a time-reversal wave propagation simulation with a 3-D heterogeneous structural model was demonstrated using recordings from a nationwide strong-motion seismograph network during the 2007 Off Niigata, Japan, M w 6.6 earthquake, and the 2007 Off Ibaraki, Japan, M w 6.8 earthquake. Such data-assimilated-based simulations are also effective for early forecasting of strong ground motions caused by large earthquakes through fast time-advancing simulations based on the current assimilated wavefield. We will discuss the feasibility of a disaster prevention system for the early forecasting of strong motion disasters due to large earthquakes, based on repeatedly estimating source parameters and forecasting strong motions in future time based on the current assimilated wavefields. [ABSTRACT FROM AUTHOR]

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In June 2016, the Ministry of Land, Infrastructure, Transport and Tourism in Japan announced a countermeasure against the Nankai Trough's long‐period ground motions. However, the response spectrum method provided in the Ministry of Construction notification Vol. 2009 was not included in the countermeasure because it could not reflect the influence of long‐period ground motions. Therefore, this paper proposes a damping correction formula for long‐period ground motions considering the period‐dependent characteristics of the earthquake response spectra for the design. The applicability of the proposed damping correction formula to seismically isolated buildings is verified by comparing the result by the response spectrum method using this formula with those of a time‐history analysis using the single‐degree‐of‐freedom models. [ABSTRACT FROM AUTHOR]

This paper studies the causal effect of the voluntary contributions of labour to local services, in the form of voluntary provision of daily care to the elderly, on elderly mortality. To identify the causal effect, I exploit the earthquake that occurred in mid-western Japan in 1995 as a natural experiment inducing exogenous variation in the level of contributions. Based on a comparison of mortality between the municipalities that recorded little or no loss of life due to the earthquake but experienced a sharp increase in the level of contributions, and the nearby municipalities that were not hit by the earthquake, I find that the voluntary provision of daily care to the elderly significantly reduced elderly mortality. A series of robustness checks and falsification exercises are conducted to confirm that the results are not driven by the direct effects of the earthquake. [ABSTRACT FROM AUTHOR]

Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. B Correction: Progress in Earth and Planetary Science (2023) 10:8 b https://doi.org/10.1186/s40645-023-00540-8 After publication of this article (Ikehara et al. [1]), it was brought to our attention that one of the reviewer's name in the acknowledgments of the paper is incorrect, it should be changed from Dr J.N. Prost to Dr J.N. Proust. [Extracted from the article]

The concept of determining the dislocation Love numbers using GNSS (Global Navigation Satellite System) data and calculating the corresponding Green's functions is presented in this paper. As a case study, we derive the dislocation Love number h of vertical displacement by combining 1232 onshore GPS data and 7 GPS-Acoustic data with the 2011 Tohoku-Oki earthquake (M w 9.0). Three fault-slip distributions are used to compare and verify the theory and results. As the GPS stations are only located in Japan Island and along the Japan trench, we use the theoretical vertical displacements of a spherically layered Earth structure to constrain the low-order signal. The L-curve and an a priori preliminary reference skill are applied in the inversion method. Then, the GPS-observed vertical displacement changes are used to invert for the vertical displacement dislocation Love numbers h based on three different fault-slip models. Our results indicate that the estimated dislocation Love numbers |$h$| fluctuate significantly from the earth model (i.e. the preliminary reference earth model), especially for the |$h_{n1}^{32}$| component, and these changes in |$h_{n2}^{12}$| and |$h_{n0}^{33} - h_{n0}^{22}$| are relatively small. The vertical displacements derived from the inversion results agree well with the GPS vertical observations. The inverted dislocation Love numbers are considered to profile the regional structure which differs from the mean 1-D heterogeneous structure of the Earth, and the corresponding Green's functions of four independent dislocation sources describe a more reasonable seismic deformation field. [ABSTRACT FROM AUTHOR]

Natural time analysis has led to the introduction of an order parameter for seismicity when considering earthquakes as critical phenomena. The study of the fluctuations of this order parameter has shown that its variability exhibits minima before strong earthquakes. In this paper, we evaluate the statistical significance of such minima by using the recent method of event coincidence analysis. Our study includes the variability minima identified before major earthquakes in Japan and Eastern Mediterranean as well as in global seismicity. [ABSTRACT FROM AUTHOR]

Japan is in the Pacific Rim Seismic Belt, and earthquakes happen frequently. Foreigners who lack the necessary earthquake knowledge and escape skills may not survive strong earthquakes in Japan. Therefore, it is essential to provide earthquake education to these foreigners. Since rich-formed earthquake education has been available for foreigners living in Japan, this research works to improve the earthquake education situation for foreigners who intend to visit Japan. Receiving earthquake education in advance helps enhance foreigners' earthquake risk awareness, gain more opportunities to master earthquake survival knowledge, and build earthquake survival confidence. This paper proposed a learning model called 'FOE+G' to achieve the research goals. 'FOE' means the frequency of occurrence of earthquakes in Japan, and 'G' means gamification. A prototype system in the form of a cross-platform application has been developed to confirm that the learning model improves earthquake education for the target audience. The application delivers an earthquake notification to target objects each time an eligible earthquake occurs in Japan. The High-frequency earthquakes in Japan lead to relatively frequent updates, which enable users to build earthquake awareness, realise the importance of earthquake education, and participate more actively in it. Furthermore, gamification is employed in the application to prompt participation in earthquake education. [ABSTRACT FROM AUTHOR]

Earthquake early warning (EEW) systems can give people warnings before damaging ground motions reach their site and can reduce earthquake-related losses. It has been shown that Bayesian reference can be used to estimate earthquake magnitude, location, and the distribution of peak ground motion using observed ground-motion amplitudes, predefined prior information, and appropriate attenuation relationships. In this article, we describe a Bayesian approach to earthquake early warning (EEW) systems for the estimation of magnitude (M) and peak ground-motion velocity (PGV) using the Gutenberg–Richter relation as a priori probability derived from statistical historical earthquake information from the Japanese KiK-net. Moreover, using the magnitude Mj = 4.5 and PGV = 0.4 cm/s as the warning threshold, an earthquake hazard discrimination model was established. Following this, the proposed approach was compared with the traditional fitting method to analyze the earthquake hazard discrimination using an Mj = 4.3 earthquake in the Mt. Fuji area and an Mj = 5.5 earthquake in the Ibaraki area of Japan as examples. The results are as follows: (1) The probabilistic algorithm founded on the predictive model of the magnitude from the average period (τc) and PGV from the displacement amplitude (Pd) from the initial 3 s of the P wave is able to provide a fast and accurate estimation of the final magnitude and location. (2) The Bayesian inference approach for the earthquake hazard discrimination model has a 2.94% miss rate and a 5.88% false alarm rate, which is lower than that of the traditional fitting method, thus increasing the accuracy and reliability of earthquake hazard estimation. [ABSTRACT FROM AUTHOR]

SUMMARY: To rapidly and accurately provide alerts at target sites near the epicentre, we develop an on-site alert-level earthquake early warning (EEW) strategy involving P -wave signals and machine-learning-based prediction equations. These prediction equations are established for magnitude estimation and peak ground velocity (PGV) prediction accounting for multiple feature inputs and the support vector machine (SVM). These prediction equations are called SVM-M model for estimating magnitude and SVM-PGV model for predicting PGV, respectively. According to comparison between the predicted magnitude and PGV values with the predicted threshold values (M = 5.7 and PGV = 9.12 cm s–1, respectively), different alert level (0, 1, 2, 3) is issued at the different recording site when the predicted magnitude or PGV values exceed the given threshold values. Alert level 3 means that both the predicted magnitude and the predicted PGV exceed a given threshold, and there may be serious damage in this recording site. We apply the method to three destructive earthquake events (M ≥ 6.5) occurred in Japan, and our results indicate that with regard to the performance of SVM-PGV model for predicting PGV, at 3 s after P -wave arrival, the percentage of successful alarms (SAs) for these three events is higher than 95, 73 and 94 per cent, respectively, and the percentage of false alarms approaches 0. Additionally, with regard to the performance of SVM-M model for estimating magnitude, at 3 s after P -wave arrival, the percentage of SAs for these three events exceeds 95 per cent, and the percentage of missed alarms approaches 0. Moreover, almost all stations in the areas PGV ≥ 16 cm s–1 (IMM ≥ VII) near the epicentre issue alert level 3. The proposed method provides potential applications in EEW system. [ABSTRACT FROM AUTHOR]

In this study, we report atmospheric electric field (AEF) anomalies observed around the time of earthquakes (EQs) in Japan. Using a newly developed AEF observation network with three spatially separated stations in Japan (Chofu, Kakioka, and Iwaki), we conducted a study for two EQs that occurred within a few 100 km from the EQ epicenter under relatively good local weather conditions as shown by a local all-sky camera and weather information. Time series and wavelet analyses of the AEF indicate that fluctuation anomalies in the AEF with periods of 10–60 min and larger than 70 min were observed from a few hours before up to a few hours after the occurrence of the EQs. The lag in the onset time increased with increasing distance from the EQ epicenter to the field site. The above-mentioned characteristics of these AEF fluctuation anomalies were similar among the three stations, and therefore the observed AEF anomalies were considered to be an imminent precursor of EQs. The observed AEF anomalies were likely to be caused by internal gravity waves (IGWs) generated around the EQ epicenter a few hours before the EQ, passing over the field site while changing the AEF by changing the space charge density in the surface layer of the atmosphere. [ABSTRACT FROM AUTHOR]

The presence of seismo-lower ionospheric perturbation for the Kobe earthquake (EQ) has been revisited with a relatively new phenomenon of ULF (ultra-low-frequency) magnetic field depression effect. By using the ULF data in Japan only at Kakioka belonging to Japan Meteorological Agency (because data from Memambetsu and Kanoya were not available), we have found that a very clear ULF depression was observed at Kakioka on 14 January 1995. A comparison with our former result on subionospheric VLF (very low frequency) propagation anomaly indicates that the occurrence of ULF depression exhibits a temporal coincidence (synchronization) with that of subionospheric VLF anomaly. This may be acceptable because the ULF depression can be explained in terms of enhanced absorption of magnetospheric ULF waves through the disturbed lower ionosphere prior to an EQ. The result of ULF magnetic field depression in this paper is likely to provide a further support to the presence of the lower ionospheric perturbation before the Kobe EQ. [ABSTRACT FROM PUBLISHER]