The “Engineering for Resilient Society (ERS)” research group of the Institute of Industrial Science, the University of Tokyo, held a symposium “Damage due to the 2024 Noto Peninsula Earthquake and the Way forward” during the Komaba Research Campus Open House in June 2024. The 2024 Noto Peninsula Earthquake occurred at 16:10 on January 1, 2024, and caused diverse damage, including the collapse of many houses, spreading fires in Wajima City, inundation by tsunami, coastal uplift, and liquefaction in a wide area, etc. This report provides an overview of the symposium and the exhibition.

In this report the damage of the ceilings in large rooms due to two earthquakes, which are Noto-Peninsula Earthquake occurred in Ishikawa and Toyama region on January 1, 2024, and Bungo Channel Earthquake occurred in Uwajima coast on April 17, is reported. In Toyama city the ceiling in Pachinko Hall was collapsed, though it was by 80km far from the epicenter. The fallen ceiling, suspended above the main aisle, hit the heads of customers running for outdoors for evacuation. In Uwajima city suspended ceiling was failed and fallen onto the seats in a music hall.

This research was conducted to evaluate the seismic performance of timber-masonry composite structures commonly found in the Sagaing region of Myanmar, and to provide a sustainable retrofitting method that can also be applied to similar buildings in other areas to enhance their resilience against earthquakes.

In this study, shaking table tests were conducted to observe and compare the seismic responses of timber-masonry mixed structures. Three 1:4 scale house models with a curing period of 14 days were constructed: a non-retrofitted model, a model with tire straps, and a model with the addition of silicone rubber to simulate the properties of tire rubber, with tensile strength scaled down according to similitude law. Additionally, the study included material strength tests of mortar mix designs and rubber strength tests to ensure the proper use of these materials in the scale models according to similitude law and scaling factors.

This study implemented disaster response headquarters operation training for both local governments and private companies, aiming to explore effective management methods. The training adopted a non-scenario-based live-action format, simulating real disaster conditions to improve participants’ skills in rapid information gathering, organization, and decision-making. As a result, participants, who initially had vague concerns about the setup and operation of disaster response headquarters, developed more specific awareness of the challenges after the training and gained a deeper understanding of its importance.

This study examines the effective approach to disaster preparedness training for Shirahama-town Tsubaki, a region in Wakayama Prefecture at high risk of isolation during a Nankai Trough earthquake. From February 15 to 16, 2024, the “The EOC at TSUBAKI” training program was conducted to evaluate methods for designing training programs and managing operations. The research highlighted the need to integrate “what” is learned, “how” it is learned, and the competencies developed in a comprehensive manner when formulating such training programs.

In order to efficiently conduct damage certification surveys for residential buildings affected by disasters, improvements have been made to allow damage certification through document verification alone, in coordination with disaster victims, fire insurance companies, condominium management companies, and others. Municipalities need to establish systems and processes to implement these measures. This study conducted a survey of municipalities across the country to assess the implementation systems, methods, and challenges related to damage certification surveys. The results clarified the actual conditions of operations and decision-making during surveys, the status of system implementation, the content and implementation of training during normal times, and future challenges in collaboration with local residents and private companies for faster issuance of damage certification forms and surveys. Additionally, based on the findings of this survey, a training program for residential building damage certification was developed.

In the 2024 Noto Peninsula Earthquake, many isolated communities emerged, highlighting the challenges of maintaining daily life and implementing disaster countermeasures in those areas. In response, the authors held the “Isolated Community Summit 2024 at TSUBAKI,” a two-day event in the Tsubaki district of Shirahama Town, Wakayama Prefecture, an area expected to be isolated in the event of a Nankai Trough Earthquake. The summit aimed to discuss how disaster countermeasures should be promoted from a regional perspective, drawing on the lessons learned from the Noto Peninsula Earthquake. Various events, including demonstrations of the heavy machinery spider, were also held. After the event, a survey was conducted to assess changes in disaster awareness. The results revealed that many participants had gained a deeper understanding of the concepts of self-help, mutual assistance, and public assistance, and showed a shift in their awareness towards implementing concrete disaster preparedness measures within the community.

The 2024 Noto Peninsula Earthquake caused severe damage, prompting the deployment of support personnel from across the country to affected municipalities. To investigate the attributes, skills, and disaster response tasks of these personnel, we conducted a survey targeting the dispatched support staff involved in disaster response. Responses were received from 3,499 individuals across 553 municipalities. The results showed that male personnel were predominantly dispatched, regardless of disaster response experience or tenure. Additionally, tasks such as housing damage assessments and shelter management were identified as key responsibilities, with roles shifting as the response progressed.

Since the first private condominium was built in Japan in 1956, condominiums have become a major form of residence, particularly in urban areas. However, as both buildings and residents age, disaster management has emerged as a significant challenge. The 1995 Hanshin-Awaji Earthquake and the 2011 Great East Japan Earthquake caused considerable damage to condominiums. Currently, disaster management by management associations remains insufficient, especially regarding earthquake resistance, evacuation routes, and lifeline measures. This study aims to develop a framework to systematically assess and enhance disaster management in condominiums.

In 2019, Typhoon No. 15 (Boso Peninsula Typhoon) caused a large-scale disaster in Kisarazu City, the first in about six years to necessitate resident evacuation. The city recorded a maximum instantaneous wind speed of 49.0 meters per second, with particularly severe damage to roof tiles. Additionally, there were 23,000 power outages, with full restoration taking 17 days. In response to this disaster, a disaster response headquarters was established, and various support activities, including the opening of evacuation centers, were carried out. However, delays in information sharing and a lack of role recognition among departments emerged as significant issues. Based on these reflections, Kisarazu City introduced the “Disaster Net” and the “BOSS System” in 2020 to improve disaster response. This paper aims to review the construction process of the BOSS System, confirm its effectiveness, and promote information sharing and enhanced coordination. Future challenges include the integration of the BOSS System across Chiba Prefecture and strengthening collaboration with disaster prevention DX.

In this study, we developed a safety confirmation system that enables individuals, including vulnerable groups, to easily confirm their safety during large-scale disasters. The system is specifically designed for elderly people and children who do not have smartphones, utilizing QR codes for safety confirmation. By wearing a QR code, third parties can transmit safety information via their smartphones, and the system is designed to incorporate alternative methods in cases of prolonged power outages or communication difficulties. The effectiveness of the system was evaluated during drills in Shirahama Town, Wakayama Prefecture, and Kushiro City, Hokkaido.

The purpose of this study is to conduct a fundamental assessment of disaster risks to enable Japan Post Co., Ltd. to effectively respond to disasters and enhance its response capabilities, in order to fulfill its responsibilities as a designated public institution. This paper focuses specifically on flood risk and evaluates the inundation risk at post offices nationwide, which provide postal and logistics functions. To assess the flood risk, we imported flood inundation forecast area data and post office location data into QGIS and visualized the inundation risk at each location. As a result of evaluating 1,158 locations, we identified locations at risk of flooding, visualized them on a map, and clarified the risk trends for each prefecture through an exposure assessment.

Recently, the word of “disaster resilience” started to be used. However, it has a wide range of interpretation and it is difficult to say that a unified concept exists. The author defines that “disaster resilience” consists of four elements: (1) robustness to avoid fatal damage, (2) rapid and smooth recover, (3) building back better, (4) emergency response for disaster reduction, and it is important to take disaster countermeasures that combine these elements in a balanced manner. This paper discussed this author’s definition with existing interpretations and also presented the points to be considered with “disaster resilience” in the future.

This study focuses on the effects of small-strain shear moduli G₀ of clean sands to the volumetric strain induced under drained cyclic loading. Using a strain-controlled triaxial apparatus, sand specimens were reconstituted by different sample preparation methods to the same relative density at around 75 %, and then subjected to uniform cyclic loading in drained conditions. During the experiments, shear wave velocity V_s was recorded, and both total and local volumetric strains were measured and compared. For the dry-tamping specimen having a higher V_s (G₀), the resulting volumetric strains were significantly lower than that observed in the air-pluviated specimen. The differences suggest that at a certain relative density, the stronger soil fabric reflected in G₀ can be associated with greater resistance to volume change due to drained cyclic loading and this corroborates with the previous findings - the higher the G_0, the slower excess pore water pressure generation and hence more resistant to liquefaction it is. The results highlight the importance of both density and fabric effects to liquefaction characteristics of sandy soils.

Large-strain liquefaction tests were conducted on sandy soil containing non-plastic fine particles using a medium-sized hollow torsional apparatus, and to analyze the behavior of sandy soil containing non-plastic fine particles, including the large-strain region during liquefaction. As a result, the number of cycles to liquefaction of sandy soil with 10% fines was similar to that of sandy soil without non-plasticized fine particles, and the large-strain liquefaction characteristics were also similar. On the other hand, sandy soils with 20% fines showed more pronounced shear strain development than sandy soils with non-plastic fine grained content of 10% or less, and this trend remained unchanged up to a large-strain region with double amplitude shear strain of 100%. When Fc=30% or more, the φ_mob/φ_f to Σ∆W/σ’_c relationship was observed to exhibit more stickiness before φ_mob/φ_f reaches its peak compared to sandy soils with Fc=20% or less.

This paper presents an evaluation of the quality of samples obtained from loose sandy soils using a small-scale freezing sampling method. Utilizing a pressure chamber to account for in-situ confining pressures, we focused on changes in relative density (D_r) and small-strain shear modulus (G₀) to assess the quality of frozen samples extracted. We investigated the effects of freezing speed on sample integrity. Experimental results indicated that the presence of the freezing tube tends to densify loose sandy soils, and that higher freezing speeds can lead to frost heave. These findings suggest that by implementing appropriate freezing tube insertion methods and controlling the freezing speed, the small-scale freezing sampling method can be effectively applied to loose sandy soils.

The log pile press-in method for liquefaction countermeasures is a technique that increases ground density by the volume of the pressed-in log piles. This study examines how the volumetric strain within the ground changes during pile press-in, depending on variations in pile friction. Image analysis results indicate that shorter distances between piles lead to a more pronounced increase in density between piles, and that increasing pile friction enhances ground density. This friction increase restricts the upward movement of sand during press-in, facilitating density improvement.

This report summarizes the damage survey of liquefaction and associated lateral flow that occurred in Uchinada Town, Ishikawa Prefecture, due to the 2024 Noto Earthquake. The damage survey was conducted in four areas: Kurisaki, Tsurugaoka, Miyasaka and Nishi-araya. The overall damage trends in the survey area were as follows: the main causes of damage to houses were subsidence due to a reduction in bearing capacity associated with liquefaction and deformation due to lateral flow, and there were also some houses that were damaged by a combination of these two factors. The ground fissures at the top of the lateral flow were only a few tens of centimeters, and there was almost no sand ejecta, while large amounts of sand ejecta were occasionally observed at the bottom of the lateral flow slope. In many cases, the liquefaction-induced lateral flow stopped at the road at the bottom of the slope, however, in the Nishi-Araiya district, compression at the boundary between the road and slope and uplift of the road were observed more frequently than in other districts, and the extent of the damage was also more significant. In addition, in the Nishi-Araiya district, it was confirmed that the buildings with pile foundations within the lateral flow area reduced the extent of the flow damage.

This review discusses the mechanism of large-scale flow-type landslides, which are extremely rare geohazards, focusing on the topography and geotechnical conditions of the landslides that occurred in the 2018 Sulawesi earthquake in Indonesia and the 2023 Jishishan earthquake in China. It was confirmed that there were important characteristics in common that led to the occurrence of the landslides, such as the dry alluvial fan above the landslide area, the conditions of the flow and sedimentation areas, the presence of spring water, and the soil characteristics of the landslide area. In addition, although there is no record of a similar flow-type landslide in Japan in the past, there is a local folklore from the Middle Ages about a destruction of coastal village in Ikuji district of Kurobe City. This is an assumption based on limited information, however, the topography and geotechnical conditions of the Ikuji district are similar to those of the landslides in the Sulawesi earthquake, and it is possible that the landslides in Ikuji could be explained by the same mechanism.