The heavy rainfall in August 2021 continued in western and eastern Japan, and the total rainfall nationwide was comparable to the heavy rainfall in July 2018. Based on the analysis results of past heavy rainfall cases, we estimated the number of victims due to this heavy rainfall from the ratio to historical record of rainfall indicators such as 3, 6, 12, 24, 48, and 72 hour precipitation and soil water index. As a result, the number of victims was estimated to be about 25, then actual numbers of victims was about half. The number of victims of this heavy rain was reduced to about 1/20 of the heavy rain in July 2018. The number of victims was suppressed despite the high total precipitation, because the 48, 72-hour precipitation and soil water index at each point didn’t greatly exceeded the historical record so far. It seems that the occurrence of sediment disasters and river flooding was limited, and then the number of victims was suppressed.

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Recent earthquakes, such as the 2011 off the Pacific coast of Tohoku Earthquake, the 2016 Kumamoto Earthquake, and the 2018 Hokkaido Eastern Iburi Earthquake, have triggered landslides in gentle slopes in reclaimed valleys and resulted in severe damage to housing lots. In this study, we detected reclaimed valley deformation in Sendai city occurred during the 2011 off the Pacific coast of Tohoku Earthquake by InSAR and examined its background factors. Phase change corresponding to subsidence or decorrelation was observed where actual damages have been reported. Additionally, we detected up to ~10 cm of displacements away from the satellite on some reclaimed valleys where no damage to housing lots has been reported. On many of the subsided areas, we found a proportional relation between the thickness of the reclaimed soil and the amount of displacement, suggesting that one of the mechanisms of the deformation is the compaction of soil due to the strong seismic motion. These results demonstrate the validity and usability of InSAR on detecting reclaimed valley deformation.

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The nursing facility C located near the Sashiki River was flooded due to Heavy Rain in July 2020. The survey method was an interview survey on the damage situation and evacuation behavior. In addition, a flood inundation analysis was conducted. Judging from both the execution and the process of flooding, facility C missed the timing of the evacuation action. The main reasons were that the event was beyond one’s expectation, information was not helpful, lack of manpower, flooded water rose fast. The lessons of this experience are action plan using information, nighttime emergency system, evacuation drills with multiple patterns. For the safety of elderly people, both an evacuation security plan and a business continuity plan (BCP) are needed. On the other hand, there are administrative issues related to wide-area evacuation. Deregulation of the long-term care insurance system and simplification of administrative procedures are desirable.

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Recent social problems include the increase in maintenance work due to aging infrastructure, frequent natural disasters, problems specific to each region and shortage of engineer. In this research, we developed low-cost and small IoT sensors to solve these problems, and conducted two demonstration experiments. As the demonstration experiment in the field of disaster prevention, the water level in the confluence of rivers in Shimonita Town, Gunma Prefecture was photographed, and the information was transmitted to SNS. As the demonstration experiment in the field of maintenance management of structures, concrete surface was photographed from the under the RC slab and their applicability was examined. In both fields, the demonstration experiment conducted smoothly. As the results, the feasibility of low-cost and small IoT sensors was confirmed.

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The Sendai City government has been implementing two measures for Disaster Risk Reduction in condominiums, Certification program for condominiums with improved disaster preparedness in Sendai the City of Trees and the system of Gambaru Hinanshisetsu condominiums. The former is certified according to definite standards, but the latter does not require any specific criteria. The purpose of this study is to clarify the level of disaster risk reduction in Gambaru Hinanshisetsu condominiums by applying Certification standards for condominiums with improved disaster preparedness in Sendai the City of Trees. As a result of the interview surveys to Sendai City government, it was found that there are 41 Gambaru Hinanshisetsu condominiums, 56 Certification condominiums for condominiums with improved disaster preparedness in Sendai the City of Trees, and 5 condominiums that satisfied both conditions. Results of questionnaire surveys revealed that Gambaru Hinanshisetsu condominiums demonstrate high potential for disaster risk reduction because, whereas they have levels of building function and disaster preparation, they showed high levels of disaster prevention activities.

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A questionnaire survey was conducted in the Kitagawa area of Nobeoka City, Miyazaki Prefecture, which was damaged by Typhoon No. 16 in 2016 , to understand the residents’ views on the flood control method using open levees and residential land raising construction, and to analyze the issues. The district, which is regularly hit by typhoons, has a heavy burden of agricultural damage and driftwood removal work, and some residents responded negatively to the use of open levees. Many of the respondents answered that they would like to see the raised levees raised even higher in consideration of the past disasters. Even after the most recent flood disaster, it could not be said that local communities and households were adequately prepared for flood damage.

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We conducted a questionnaire survey at Fujiyosida Route of Mt. Fuji in September 2021 to clarify the current state of information gathering and basic knowledge on volcanic eruptions among hikers. The result showed that more than 80 % of hikers were aware of the possibility of the eruption of Mt. Fuji. However, only about 10 % of the respondents were anxious that they might actually be involved in an eruption. Less than 10 % of the respondents gathered information about the current status of volcanic activities before climbing. Few people knew about eruption alert levels and the evacuation route map of Mt. Fuji. Based on our survey, we propose to promote information provision at the trail entrance to make it easier for hikers to gather information about volcanic risks.

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Circular elements are frequently used in the DEM simulations of granular materials. Since circular elements are easy to rotate, rolling friction has been used as a method to suppress element rotation. On the other hand, in DEM simulations using polyhedral elements, rolling friction is rarely used because the shape of the element itself has the effect of suppressing rotation. However, if the element shape is different from that of the actual granular material, the rolling resistance is also different. Therefore, the analysis results are different from the actual behavior. Therefore, in this study, rolling friction is newly introduced into the DEM using the polyhedral elements. It was confirmed whether the proposed rolling friction works in the DEM using the polyhedral elements and whether the introduction of rolling friction reduces the differences in simulation results using elements with different shapes. Specifically, simulations were performed to determine the angle of repose for elements with two different shapes (decahedral and octahedral) with varying coefficients of sliding friction and rolling friction to investigate the effect of rolling friction on the angle of repose. The effects of sliding and rolling friction on the analytical results were verified through failure simulations of a rock mass.

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This study reports the results of implementing a volcano disaster prevention seminar based on a prequestionnaire survey, conducted to ascertain residents’ awareness of disaster prevention, and clarifies residents’ understanding and risk perceptions of a volcanic eruption at Mt. Fuji. According to the survey results, residents may find it difficult to comprehend the wide range of volcanic phenomena caused by Mt. Fuji’s eruption. We then designed a seminar to address the gaps from the survey. The analysis of course discussions and the post-seminar questionnaire revealed that participants understood the movement, speed, and range of the volcanic phenomena generated by Mt. Fuji’s eruption. The results of this study will help implement risk communication strategies such as dissemination and awareness-raising about the risk of Mt. Fuji’s eruption.

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Recently, Flood Crisis Management Water Level Gauges have been installed, but their use as a disaster response of the local community has not progressed. In this research, a questionnaire survey was conducted in local governments of Mie Prefecture and the communities in Ise City, because gauges may not be fully utilized in the local communities. As a result of this survey, it was shown that the gauges are used by the local governments, but not by the local communities. The result shows the issues that residents are unaware of the gauges and have not determined how to utilize them yet.

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In this study, we applied debris flow simulations on 2014 August Hiroshima disaster. We focused on water supply volume calculated from rainfall to the basin area. From results, many torrents especially in small basin and granite showed lack of water to behave as the real disaster. We assumed that the water supply from neighboring and internal mountain such as ground water affects to the debris flow scale. We also considered that it relates to three-dimensional topography, which can be described with basin volume. From results, basin volume showed good relationships with the debris flow scale than using basin area.

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This study aims to examine journalistic activities in disaster reporting by analyzing media frames of newspaper articles covering the debris flow disaster in Atami City, Shizuoka Prefecture, in July 2021. The deductive approach using the frame model proposed by Thorson (2012) finds that “Blame”frame was used from the beginning and then became dominant, and that “Devastation, ” “Helplessness” frames preceded “Solidarity”frame. Such framing may have the adverse effects, such as trivializing the universal issue as a particular region's problem, and causing convergence of media coverage. A possible reason why journalists use these frames could be media routines, the practices formulated within mass media organizations. A result shows that journalists are required to reconsider media routines and frames to report the complex and multifaceted reality of disasters.

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The remaining amount of production under lifeline disruptions are called lifeline resilience factors, and are basic indicator to estimate economic impacts on industrial sector. This indicator reflects resistance and adaptability characteristics of each firm under lifeline disruptions and it depends on business contents. This paper estimates resilience factor under transport network deteriorations, which have not been thoroughly investigated and quantified in previous research. The recovery process of sales levels and transport network performances under transport network deteriorations in the heavy rain event of July 2018, are estimated based on questionnaire and mobile data. The relationship between sales levels and transport network performances are modeled. As a result of modeling, it is shown that sales levels decrease to zero on the case of decreasing transport network performances to 40%.

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Blowing-snow disaster damage includes road infrastructures, vehicles and road users. The damage is caused by visibility hindrance or snow drifts or both of those phenomena that are complicatedly interacted. To manage the blowing-snow disaster risks, drivers’ cancelling a drive trip or road administrators’ closing roads prior to the expected disaster will be effective as the risk avoidance measures. To timely realize in-advance risk avoidance actions, activating risk communications among the stakeholders including meteorologists, road administrators, media and road users will be vital as they could share the information on the disaster risk from blowing snow. Continually improving the risk communications through the PDCA Cycle may strengthen countermeasures that are realized by the stakeholders against blowing-snow disasters, which will result in the enforcement of social controllability of blowing-snow disaster risks.

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In this study, we focused on the characteristics of people's sensory perception of rainfall, and identified variations in people's perception of rainfall intensity, rainfall length, and landslides, as well as differences in the perception of rainfall that occur among individuals, and classified how people perceive rainfall. The survey was conducted on fourth graders and their parents at Tochio Elementary School in Takayama, Japan. As a result, it was found that there were variations in the intensity and length of the rainfall and the perception of landslides among the children and their parents, making it possible to visualize how the children and their parents feel about rain. It is suggested that each feeling can be classified into three groups, and that it is possible to show the tendency of each group 's sensation.

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This study evaluated the stability of wide-area slopes in Atsuma Town using open topographic data before and after the damage caused by the Hokkaido Iburi Earthquake by using GIS software. The parameters of the straight slip were determined from the results of previous surveys and numerical elevation models before and after the disaster. As a result, unstable areas were extracted over a wider area than the area where the slope failed due to the earthquake. In addition, the influence of each parameter applied to the straight slip on the safety factor is examined and the results obtained in this study are discussed. It was found that the actual slope failures during the earthquake could be reproduced better by taking into account the reduction of horizontal seismic intensity according to the direction of slope inclination.

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In this study, we consider present situation and issues of simplified building damage assessment methods for storm and floods based on interviews to local government officials. From previous studies, we have systematized the current use of simplification methods into six types. We Interview local government officials who were engaged in disaster response for Typhoon Hagibis in October 2019. Through the survey, it became clear that they efficiently carried out its operations while successfully incorporating the simplified methods. On the other hand, in the case of more extensive damage or in the case of earthquake disasters, similar methods cannot be used, and therefore, it is essential to discuss in advance the multiple hazards faced and the scale of damage.

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