The Global Navigation Satellite System (GNSS) has been utilized in a variety of research fields within the geosciences. This research has been further developed for application to hazard monitoring and natural disaster mitigation. Some developments have even been implemented in society in countermeasures against natural disasters. The Geospatial Information Authority of Japan (GSI), for example, has established a nationwide GNSS network called GEONET. The data from GEONET are used extensively among researchers and practitioners, not only for basic research but also for the development of methods and systems that can mitigate disasters. This special volume is a collection of articles that discuss how such methods and systems are now being developed and/or planned to both clarify the mechanisms behind natural hazards and mitigate the damage they may cause. The volume consists of 13 papers covering a wide range of natural phenomena, such as earthquakes, crustal movements, tsunamis, ionospheric disturbances, and volcanic eruptions. Some papers help us to understand how natural hazards behave, which should be the first step toward disaster mitigation. On the other hand, other articles report direct efforts made toward providing early warnings of impending disasters. Disaster mitigation systems may require real-time (and even kinematic with high-rate data sampling) processing and dissemination of data. Moreover, some applications involve data collection from coastal waters and the open sea. Now that the density of GNSS stations has approached saturation on land, the scarcity of data collected offshore will have to be rectified through the development of GNSS systems in the ocean. We do hope that this volume will be a step in the further progress of utilizing GNSS for disaster monitoring and mitigation in the future to make society safer and more secure.

The Third JDR Award ceremony was held in Kanda, Japan, at November 14, 2017 and the prize was given to Professor Shunichi Koshimura, International Research Institute of Disaster Science, Tohoku University, Japan. We congratulate the winner and sincerely
wish for future success.

It is our great pleasure to present the Third JDR Award to Professor Shunichi Koshimura for his outstanding contributions to the Journal of Disaster Research (JDR) as the author of 27 JDR articles and the guest editor of three special JDR issues.

Dr. Koshimura started his academic career as a young and promising researcher in the field of tsunami disasters. He is now a full professor at Tohoku University’s International Research Institute of Disaster Research, where he specializes in remote sensing and geoinformatics for disaster management.

It is our conviction that Professor Koshimura will be productive in both researching and teaching disaster risk reduction for many decades to come, reflecting his rich and profound professional experience with the 2011 Great East Japan Earthquake and Tsunami Disaster.

I am honored to receive the Third JDR Award, and I am very grateful to the editorial committee members and staff of the Journal of Disaster Research (JDR). I also wish to express my gratitude to all the authors who contributed to the papers in three special issues entitled “Disaster and Big Data,” which were published in 2016, 2017, and 2018. I really enjoyed the opportunities I had in guest editing the 36 excellent papers in the special issues.

My approximately 30 publications in the JDR include the outcomes from the international joint research projects of SATREPS Indonesia, Peru, and Chile, so I would like to share the delight of receiving the JDR award with all the research members of the projects and thank them for their fruitful collaboration.

The Journal of Disaster Research all across the wide and comprehensive scope of its outstanding research has provided topical and valuable insights as well as significant implications for disaster reduction and management. I do hope I have contributed to making the JDR an excellent publication of valuable disaster research findings from around the world.

Shunichi Koshimura

March 8, 2018

The 2011 Great East Japan Earthquake and Tsunami Disaster left behind many lessons to learn, and there have since been many new findings and insights that have led to suggestions made and implemented in disaster observation, sensing, simulation, and damage determination. The challenges for mitigating the damage from future catastrophic natural disasters, such as the Tokyo Metropolitan Earthquake or the Nankai Trough Earthquake and Tsunami, are in how we share our visions of the possible impacts, how we prepare to mitigate the losses and damages, and how we enhance society’s disaster resilience.

The huge amount of information obtained, called “disaster big data,” is related to the dynamic movement, as IoT, of a large number people, vehicles, and goods from inside and outside the affected areas. This has dramatically facilitated our understanding of how our society has responded to unprecedented catastrophes. The key question is how to utilize big data in establishing social systems that respond promptly, sensibly, and effectively to natural disasters, and in withstanding adversity with resilience.

Researchers with various types of expertise are working together under a collaborative project called JST CREST “Establishing the advanced disaster reduction management system by fusion of real-time disaster simulation and big data assimilation.” The project aims to identify possible earthquake and tsunami disaster scenarios that occur and progress in a chained or compound manner and to create new technologies to lead responses and disaster mitigation measures to help society to recover from disasters.

As we have published two previous special issues entitled “Disaster and Big Data” since 2016, this issue is our third. Included are 14 papers that aim to share the recent progress of the project as the sequel to Part 2, published in March 2017. As one of the guest editors of this issue, I would like to express our deep gratitude for the insightful comments and suggestions made by the reviewers and the members of the editorial committee. I do hope that this work will be utilized in disaster management efforts to mitigate the damage and losses in future catastrophic disasters.

This special issue summarizes the main results of the first half of the five-year SATREPS project in Myanmar. SATREPS stands for “Science and Technology Research Partnership for Sustainable Development” and it is supported by the Japan International Cooperation Agency (JICA) and the Japan Science and Technology Agency (JST). The title of our project is “Construction of Myanmar Disaster Response Enhancement System and Industry-Academia-Government Cooperation Platform.” Ours is the first SATREPS project in Myanmar and Yangon Technological University (YTU) is our main counterpart institute and relevant organizations mainly national and local governments are collaborating as strategic partners.

In Myanmar, rural and urban development has been progressing rapidly and on a large scale, and the expansion of urban population coupled with climate change has increased the risk of disaster to a critical level, especially in Yangon, Myanmar’s largest city. By monitoring changes in the urban environment, such as the topography, ground, buildings, and infrastructure, we seek to lower the level of risk. Our project will improve the disaster management system, plan and response capability, based on an evaluation of disaster vulnerabilities. Considering floods including tidal wave problems and earthquakes as the target hazards, we aim to contribute to the development of precise regional development plans and disaster management measures by identifying disaster risks in advance, and we will support the Myanmar government in strengthening its disaster response capabilities.

We plan to set up a system by which industry, academia, and the government collaborate to promote the understanding of research content, to continue research activities, and to implement research results in Myanmar. We hope that our activities in the SATREPS project will become an ideal model for solving issues in urban development and disaster management, and that the project will also contribute the other Asian countries.

Hazard and risk researchers are using their research results to target several vastly different stakeholders: the scientific community, governmental institutions, engineers and the larger technical community, companies, and finally the local residents. Each of these groups has a different focus on the results and is drawing different conclusions from them. In this special issue for the Journal of Disaster Research (JDR), we address the problems surrounding hazard and risk communication by asking important questions. How can we communicate hazard and/or risk to the public? How can we involve communities in risk assessment? How can we raise the acceptance of risk models in communities? How can communities be involved in mitigation measures? Finally, how can we explain the inherit uncertainties of hazard and risk assessments? To answer these questions, it is essential to integrate knowledge from the social sciences, natural sciences, and engineering.

As the first step in this effort, we selected seven papers in the present special issue: six are related to the 2016 Kumamoto earthquakes in Japan and one to a research in Taiwan. They include studies on hazard and risk estimates before the disaster, risk communication during the earthquake sequence by the Japan Metrological Agency, the psychological and behavioral characteristics of disaster victims, resident evacuation patterns, the recovery process, and risk communication in disaster. The paper of the research in Taiwan addresses the importance of resident involvement to earthquake science for disaster preparedness.

In April 2016, our institute, NIED, under its new English name the “National Research Institute for Earth Science and Disaster Resilience,” commenced its fourth mid-to-long term planning period, set to last seven years.

We are constantly required to carry out comprehensive efforts, including observations, forecasts, experiments, assessments, and countermeasures related to a variety of natural disasters, including earthquakes, tsunamis, volcanic eruptions, landslides, heavy rains, blizzards, and ice storms.

Since this is NIED’s first special issue for the Journal of Disaster Research (JDR), works were collected on a wide variety of topics from research divisions and centers as well as from ongoing projects in order to give an overview of the latest achievements of the institute. We are delighted to present 17 papers on five topics: seismic disasters, volcanic disasters, climatic disasters, landslide disasters, and the development of comprehensive Information Communications Technology (ICT) for disaster management. Even though the achievements detailed in these papers are certainly the results individual research, NIED hopes to maximize these achievements for the promotion of science and technology for disaster risk reduction and resilience as a whole. It is our hope that this special issue awakens the readers’ interest in a study, and, of course, creates an opportunity for further collaborative works with us.

As our daily lives and socioeconomic activities have increasingly come to depend on information systems and networks, the impact of disruptions to these systems and networks have also become more complex and diversified.

In urban areas, where people, goods, money, and information are highly concentrated, the possibility of chain failures and confusion beyond our expectations and experience is especially high.

The vulnerabilities in our systems and networks on have become the targets of cyber attacks, which have come to cause socioeconomic problems with increasing likelihood. To counter these attacks, technological countermeasures alone are insufficient, and countermeasures such as the development of professional skills and organizational response capabilities as well as the implementation of cyber security schemes based on public-private partnerships (PPP) at the national level must be carried out as soon as possible.

In this JDR mini special issue on Cyber Security, I have tried to expand the scope of traditional cyber security discussions with mainly technological aspects. I have also succeeded in including non-technological aspects to provide feasible measures that will help us to prepare for, respond to, and recover from socioeconomic damage caused by advancing cyber attacks.

Finally, I am truly grateful for the authors’ insightful contributions and the referees’ acute professional advice, which together make this JDR mini special issue a valuable contribution to making our society more resilient to incoming cyber attacks.

At 9:26 pm on April 14, 2016, a magnitude 6.5 earthquake struck directly beneath Kumamoto prefecture, Japan, producing a seismic intensity level (JMA) of 7 in Mashiki Town. Although the earthquake damage forecasting system in operation at the time predicted that this earthquake would cause no damage, it resulted in extensive human casualties and property damage centered in Mashiki Town. Past midnight on April 16, 28 hours after the first shock, the second and main shock hit, which recorded magnitude 7.3 and was the strongest recorded urban earthquake in Japan since 1995. The hypocenter extended from Kumamoto prefecture to Oita prefecture, cutting across the island of Kyushu. Mount Aso also saw increased volcanic activities which led to several landslides. This resulted in the collapse of the Great Aso Bridge, an important transportation point, causing the loss of human lives as well as obstruction of traffic for an extended period. Much confusion arose in the process of implementing measures in response to the earthquakes, which produced damage in urban areas as well as hilly and mountainous regions, raising many issues and prompting several new approaches.

Researchers in many fields have conducted various activities at the disaster sites in the one-year period following the earthquakes, and produced significant findings in many areas. In order to make these results available to the wider global community, JDR is releasing a special issue on the 2016 Kumamoto Earthquakes with excellent papers and reports to mark their one-year anniversary. While the submitted papers to this special issue went through our regular peer review process, no publication charge was imposed so as to encourage as many submissions as possible.

It is our hope that this special issue will contribute to throwing light on the 2016 Kumamoto Earthquakes in its entirety.

Japan has one of the highest levels of seismicity in the world. In the last few decades, Japan has been the site of many destructive earthquakes, such as the 1995 Kobe earthquake, 2003 Tokachi-oki earthquake, 2004 Chuetsu earthquake, 2007 Chuetsu-oki earthquake, and 2016 Kumamoto earthquake/Tottori-chubu earthquakes.

Furthermore, we need to take disaster mitigation countermeasures in preparation for the next Nankai Trough megathrust earthquake, Tokyo earthquake, etc. Disaster countermeasures against these earthquakes will be of vital importance to Japanese society in the future.

As a specific example, if and when the next Nankai Trough megathrust earthquake strikes, it will cause widespread and compound disasters on the island of Shikoku and in southwestern Japan in general. The prefectures of Kagawa, Tokushima, Kochi, and Ehime are all on the island of Shikoku, yet the damages that a future Nankai Trough megathrust earthquake will cause are predicted to be quite different in each prefecture. Therefore, in preparing disaster mitigation strategies for the coming Nankai Trough megathrust earthquake, these four prefectures and the distinguished universities involved in disaster mitigation research and education in them must be united in collaboration while making the best use of the individual characteristics of the prefectures and universities.

Specifically, in terms of disaster mitigation preparations, universities on Shikoku have to develop and advance resilience science as it relates to upcoming disasters from a Nankai Trough megathrust earthquake, inland earthquakes, typhoons, floods, etc.

In this special issue, many significant research papers from the fields of engineering, geoscience, and the social sciences by researchers from distinguished universities on the island of Shikoku focus on resilience science. We must apply their findings to society, putting them into practice to mitigate potential damages from any future natural events.

Building a sustainable economy is one of Japan’s most pressing issues today, and the only path forward is through innovations in science and technology. Under the leadership of the Prime Minister and the Minister of State for Science and Technology Policy, the Council for Science, Technology and Innovation (CSTI) has taken a high-altitude look across Japan’s ministries, proposing a comprehensive policy for science, technology, and innovation. As part of this policy, the SIP program has been designed as a fast-track research and development project, encompassing basic research, practical adoption, and commercialization. This nationally-sponsored program for science and technology innovation crosses the traditional framework of Japan’s ministries and agencies, as well as the traditional boundaries of scientific disciplines. The SIP has identified 11 issues from the field of energy, next-generation infrastructure and regional resources in order to address social issues, revitalize the Japanese economy, and bolstering Japan’s industrial posture in the world. As one of eleven themes, a new R&D program named “Infrastructure maintenance, renovation and management” was launched in 2014. The new R&D program is a 5-years program covering various subjects with key technologies such as non-destructive testing, monitoring, robotics, long-term performance prediction, development of high-quality durable material for repair and replacement, and infrastructure management using advanced information and communication technologies (ICT). The program consists of 60 research projects involving universities, research institutes and industries. This initiative is expected to prevent further accidents and setting an example for efficient infrastructure maintenance by reducing the burden of maintenance works and costs. This special issue aims at introducing some of the activities of the ongoing SIP “Infrastructure maintenance, renovation and management.” We are delighted to see publication of twenty-one technical papers/reports on this theme. We hope that readers would find this special issue interesting and valuable; and we greatly appreciate the authors for their contributions.

6 years have passed since the 2011 Great East Japan earthquake. Many new findings, insights and suggestions have been made and were implemented in disaster observation, sensing, simulation, and damage determination. The challenges for disaster mitigation against future catastrophic natural disasters, such as the Tokyo metropolitan earthquake and Nankai Trough earthquake, are how we share the visions of the possible impacts and prepare for mitigating the losses and damages, and how we enhance society’s disaster resilience. A huge amount of information called “disaster big data” obtained, which are related to the dynamic flow of a large number of people, vehicles and goods inside and outside the affected areas. This has dramatically facilitated our understanding of how our society has responded to the unprecedented catastrophes. The key question is how we use big data in establishing the social systems that respond promptly, sensibly and effectively to natural disasters, and in withstanding the adversities with resilience. Researchers with various expertise are working together under the collaborative project called JST CREST “Establishing the most advanced disaster reduction management system by fusion of real-time disaster simulation and big data assimilation.” The project aims to identify possible disaster scenarios caused by earthquake and tsunami that occur and progress in a chained or compound manner and to create new technologies to lead responses and disaster mitigation measures that encourages the society to get over the disaster. This special issue titled “Disaster and Big Data Part 2,” including 13 papers, aims to share the recent progress of the project as the sequel of Part 1 published in March 2016. As an editor of this issue, I would like to express our deep gratitude for the insightful comments and suggestions made by the reviewers and the members of the editorial committee.

Based on the lessons from the 2011 Great East Japan Earthquake Disaster, the Ministry of Education, Culture, Sports, Science and Technology has launched “Special Project for Reducing Vulnerability for Urban Mega Earthquake Disasters (2012–2016)” with the aim of reducing the damages caused by the urban earthquake disasters such as the projected earthquake that directly hits Tokyo area and the Tokai, Tonankai and Nankai Earthquakes as much as possible. This project is divided into the following three subprojects: namely, 1) “Research and Study on Evaluation of Risk and Hazard of Earthquake that Directly Hits Tokyo Area” represented by Professor Naoshi Hirata, Earthquake Research Institute, the University of Tokyo; 2) “Research and Study on Maintenance and Recovery of Functionality in Urban Infrastructures” represented by Professor Masayoshi Nakashima, Disaster Prevention Research Institute, Kyoto University; and 3) “Research and Study on Measures to Improve Urban Resilience to Earthquake Disaster” represented by Dr. Haruo Hayashi, President of the National Research Institute for Earth Science and Disaster Resilience. This special issue focuses on the findings of the subproject 3). The subproject 3) aims to develop the information communication system for supporting efficient management of emergency responses and restoration efforts and promotion of the capabilities for solution of the problems in terms of disaster, i.e. disaster management literacy, to contribute to high resilience to disaster in our society.

In March 2015, the Third World Conference on Disaster Risk Reduction adopted the Sendai Framework for Disaster Risk Reduction with a two-part goal: to prevent new and reduce existing disaster risks through the implementation of integrated and inclusive measures that prevent and reduce hazard exposure and vulnerability to disaster, and to increase preparedness for response and recovery, thus strengthening resilience. The first priority for action was given to ”understanding disaster risk,” including focusing on the collection and use of data, risk assessment, disaster prevention education, and awareness raising. The stance of emphasizing science and technology was clearly expressed.

In September 2015, the UN Summit meeting adopted the 17 goals of the 2030 Agenda for Sustainable Development. Four of the 17 goals include targets related to disaster prevention and mitigation, which has given rise to active discussions over measurement methods and indicators for the targets. The Paris Conference of the UN Climate Change Conference (COP21), held from the end of November to early December 2015, placed an emphasis on the importance of science and technology in both mitigation and adaptation.

In light of these international discussions and their outcomes, we called for papers on the following three topics for this special edition featuring water disasters.

• (1) Prevention of new water disaster risks: rainfall prediction, flood and drought prediction, river bed change prediction, climate change, land use plans, etc.
• (2) Reduction of existing water disaster risks: disaster data and statistics, risk monitoring, risk assessment, etc.
• (3) Resilience reinforcement and inclusive measures: disaster recovery, risk communication, competence development, etc.

Nineteen papers were applied to this special issue. All papers were peer reviewed, and sixteen papers are included herein. We received invaluable comments and suggestions for all applications from the points of view of various fields from many experts in Japan and overseas. We would like to express our gratitude for these.

The Standing Technical Committees on Disaster Risk Management (CDRM) of the World Federation of Engineering Organizations (WFEO) play an important role in collecting and disseminating DRM-related information and knowledge that will conceivably help engineering society members take effective disaster mitigation measures. As part of achieving this mission, the CDRM conducted two important 2015 events – the WFEO-CDRM Special Session on Disaster Risk Management at the 11^th International Conference of the International Institute for Infrastructure Resilience and Reconstruction (I3R2) (I3R2 session) held in Seoul, Korea, and the 9^th Joint International Symposium on Disaster Risk Management conducted in conjunction with the International Symposium on River Technologies for Innovations and Social Systems held in the 2015 World Engineering Conference and Convention (WECC2015) in Kyoto, Japan (WECC2015 symposium).

The I3R2 session featured seven presentations. During the first half, disaster-cause papers covered high typhoon tides, earthquakes, and rain-induced soil erosion. The second half focused on mitigation-measure presentations such as recovery/reconstruction and regional support for mothers and children in the event of disasters.

The WECC2015 symposium featured ten presentations by ten speakers with widely varied backgrounds in disaster mitigation, river engineering, international cooperation, UNESCO regional centers, NPO management, science and technology sections at embassies, and ferry and resort complex management. These informative, meaningful presentations close with active and informative Q&A sessions.

In this special issue, five presentations that were revised as a form of academic paper were selected and published. I hope that these papers will be utilized for further advancement of disaster mitigation measures.

The 2011 Great East Japan earthquake has shown all too clearly that disaster management and mitigation measures seen from the viewpoint of protecting society are not sufficient for addressing a national crisis such as the projected Nankai Trough earthquake or Tokyo inland earthquake whose damage is expected to exceed the present estimated damage. Our study explores the weakness against disasters in how modern Japanese society uses “reverse thinking” in which investigates studying how large-scale disasters may adversely affect society and increase damage effectively. This process profiles the worst disaster scenarios that could conceivably lead to a national crisis. Classifying these worst scenarios, we suggest policies to the problems that are common to many scenarios, and we present action plans for individual problems.
First, we conduct workshops for identifying damage magnification factors and evaluating their importance under the categories of human damage, property damage, and damage to social functions, unifying the awareness of research organization.
Second, we have researchers on 1) mortality, 2) tsunami inundation, 3) liquefaction, 4) capital function, 5) evacuation, 6) required assistance, 7) lifelines, 8) high buildings, 9) information networks, 10) government systems, and 11) economic systems analyze damage magnification conditions due to hazard, vulnerability and measure aspects.
Third, we sort potential final consequences and separate them based on commonality, and propose new policies and concrete action plans for preventing the occurrence of worst-case scenarios. This research is expected to give new paradigms in disaster management science and new ways of policy making and action planning that will minimize the undesirable consequences of catastrophic earthquake and tsunami and yield new knowledge on disaster processes and damage magnification scenarios.
Most importantly, we conclude that it is necessary to have a new Japanese governmental organization, such as a Ministry of Disaster Resilience or a Disaster Resilience Management Agency, handle these national crises.

The South China Sea Tsunami Workshop (SCSTW), initiated in 2007 by internationally recognized tsunami expert Prof. Philip L.-F. Liu at Cornell University, has been conducted eight times in the Asia-Pacific region. The SCSTW’s objective is to set up an international academic platform through which strong interactions and collaborations can be established among coastal physical oceanographers, geophysicists and engineers from the South China Sea region can meet and address tsunami generation mechanisms, propagation characteristics and the corresponding coastal effects. This workshop supports approaches to tsunami disaster protection and hazard mitigation. The 8^th South China Sea Tsunami Workshop (SCSTW-8), held in Changsha, China, from Nov. 9 to 13, 2015, was hosted by the Changsha University of Science and Technology.
Typhoon-induced storm surges and significant waves are predominant coastal disaster features of China’s east coast. One example is the latest Typhoon Meranti in Sept. 2016, which significantly damaged the infrastructure and resulted in the loss of dozens of lives in China’s coastal regions, especially in Fujian province. The study of typhoon-induced storm surges is thus highly important in coastal disaster prevention and mitigation.
This special issue consists of 7 papers focusing on the recent research progress in tsunami and storm surge presented in the SCSTW-8. Results are analyzed and discussed using different research approaches, including laboratory experiments, analytical analysis, data assessment and numerical simulation. As the editor of this special issue, I would like to express my sincere appreciation to the authors for their invaluable contributions and to the reviewers for their insightful comments and suggestions. Special thanks go to Dr. Yu Yao of the Changsha University of Science and Technology for his generous assistance in preparing this special issue. I hope readers will find the papers in this special collection both interesting and useful.

Journal of Disaster Research (JDR) published its first issue in August, 2006. Since then, we have published six issues a year on a bimonthly basis. JDR is an academic journal aimed at bringing a broad, comprehensive discussion to the subject of disasters, and thus contributing to the field of disaster prevention and reduction.
Its comprehensive coverage harbors the risk of becoming unfocussed or fostering unsubstantiated conclusions. At JDR, we have dealt with this risk by making most issues special feature issues, and inviting specialists in the relevant fields as guest editors.
The Great East Japan Earthquake occurred on March, 2011, five years after our first issue was published. It was a Mw9.0 earthquake that occurred off the Pacific coast of the Tohoku region. The earthquake triggered a tsunami which produced huge casualties, amounting to over 18,000 dead or missing persons. The disaster was accompanied by a nuclear plant accident, an unprecedented event in mankind’s history. The catastrophic accident at the Fukushima Daiichi Nuclear Power Plant, operated by Tokyo Electric Company, resulted in core meltdown and the release of radioactive material.
At JDR, we considered it our responsibility to publish, apart from our regular issues, special issues on the Great East Japan Earthquake consisting of five yearly issues beginning with the first issue in 2012. This issue, Part 5, is the final issue. We would like to thank all of the authors who submitted articles for the five special issues, the reviewers, and many others who contributed. The special issues project on the Great East Japan Earthquake will be passed down to a special issue on the 2016 Kumamoto earthquakes occurred on April, 2016 in Kumamoto, Japan.

Co-Editors:
Suminao Murakami (Editor-in-Chief; Representative, Laboratory of Urban Safety Planning, Japan)
Haruo Hayashi (Editor-in-Chief; President, National Research Institute for Earth Science and Disaster Prevention, Japan)
Hideaki Karaki (President, Foundation of Food Safety and Security, Japan)

The 2011 Heisei tsunami far exceeded the level previously anticipated, resulting in devastating impacts in Japan. This event made it clear that preparation for tsunami hazards, based on past historical data alone, is inadequate. It is because tsunami hazards are characterized by a lack of historical data – due to the fact tsunamis are rare, high impact phenomena. Hence, it is important to populate a dataset with more data by including events that might have occurred outside the recorded historical timeframe, such as those inferred from geologic evidence. The dataset can also be expanded with “imaginary” experiments performed numerically using proper models. Unlike historical data that directly represent actual tsunami events as fact, geologic evidence (for example, sediment deposits) remains a conjecture for tsunami occurrences, and tsunami runup conditions evaluated using geologic data are uncertain. Theoretical approaches require making hypotheses, assumptions, and approximations. Numerical simulations require not only the accurate initial and boundary conditions but also adequate modeling techniques and computational capacity. Therefore, it is crucial to quantify the uncertainties involved in geologic, theoretical, and modeling approaches.

Approximately 30 years ago, research on paleo-tsunamis based on geologic evidence was initiated and has been significantly advanced in the intervening years. During the same period, substantial advances in computational modeling used to predict tsunami propagation and runup processes were made. Understanding tsunami behavior, characteristics, and physics have resulted primarily from the well-organized international effort of field surveys initiated by the 1992 Nicaragua Tsunami event. Such rapidly advancing knowledge and technologies were unfortunately not sufficiently implemented in practice in a timely manner. Had this been the case, the disaster of the 2011 event would have been reduced, possibly avoiding the infamous nuclear meltdown at the Fukushima Dai-ichi Nuclear Power Plant.

Having learned lessons from the 2011 Heisei Tsunami, Japan is now attempting to develop a robust tsunami-mitigation strategy that consists of two-tier criteria: Level 1 Tsunami for structure-based tsunami protection and Level 2 Tsunami for evacuation-based disaster reduction. Tsunami intensities of Levels 1 and 2 are determined by experts’ analysis and judgments. In the United States, a probabilistic tsunami hazard analysis is now widely adopted: for example, the latest ASCE-7 inundation maps are based on the hazard level of a 2,500-year return period. But again, due to the lack of data, the probabilistic analysis must rely mainly on imaginary experiments and experts’ judgments.

The topic of this special issue focuses on the theme of uncertainty involved in tsunami hazard prediction. We review and examine uncertainties associated with tsunami simulations, near-shore effects, flow velocities, tsunami effects on buildings, coastal infrastructure, and sediment transport and deposits. Substantial uncertainty regarding tsunami hazards is likely the result of tsunami generation processes. This component, however, is not discussed here because it is closely related to the topic of probabilistic ‘seismic’ hazard analysis.

This special issue is a compilation of seven papers addressing the current status of predictabilities, and will hopefully stimulate continual research that will lead to further improvements.
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  Participants in the Third United Nations World Conference on Disaster Risk Reduction (WCDRR) in Sendai, Japan, March 14–18, 2015, discussed the successor framework of the Hyogo Framework for Action (HFA) adopted at the 2005 Second World Conference on Disaster Reduction. These two frameworks were based on the Yokohama Strategy for a Safer World adopted at the First World Conference on Natural Disaster Reduction.
  According to the Ministry of Foreign Affairs of Japan, 187 United Nations member states attended the WCDRR, together with over 6,500 participants and over 100 minister-level officials, including the heads of state of seven countries, prime ministers of five countries (including Japan), vice-presidential officials from six countries, and deputy prime ministers from seven countries. Related events included 150,000 attendees from Japan and abroad.
  The Sendai Framework for Disaster Risk Reduction 2015–2030 (SFDRR) and the Sendai Declaration were adopted by consensus as the outcome documents.   One feature of the WCDRR was the large number of citizens taking part. These included governments, international organizations, NGOs, private-sectors groups and universities. They took part in 398 symposiums and seminars, plus over 200 exhibitions and other events.
  WCDRR discussions continued even after the conference, activating the Miyagi Roundtable for Disaster Risk Reduction, whose collaborators were from industry, government, academia, regular citizens, and the media. The Sendai Future Forum on Disaster Risk Reduction was held in March 2016, one year later. Information sharing and discussions on disaster risk reduction and reconstruction are now in progress.   The most remarkable aspect of the SFDRR as a WCDRR outcome document is the identification of seven global targets on disaster risk reduction. These targets were not included in either the Yokohama Strategy or the HFA. Two reasons why the target setting is significant are as follows:
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In the years that have passed since the 2011 Great East Japan earthquake, many new findings, insights and suggestions have been made in disaster observation, sensing, simulation, and damage determination on the damage scene. Based on the lessons, challenges for disaster mitigation against future catastrophic natural disasters such as the anticipated Tokyo metropolitan and Nankai Trough earthquakes are made on how we will share visions of potential impact and how we will maximize society’s disaster resilience. Much of the “disaster big data” obtained is related to the dynamic flow of large populations, vehicles and goods inside and outside affected areas. This has dramatically facilitated our understanding of how society has responded to unprecedented catastrophes. The key question is how we will use big data in establishing social systems that respond promptly, sensibly and effectively to natural disasters how this understanding will affect adversity and resilience. Researchers from a wide variety of fields are now working together under the collaborative JST CREST project entitled “Establishing the most advanced disaster reduction management system by fusion of real-time disaster simulation and big data assimilation.” One objective of this project is to identify potential disaster scenarios related to earthquake and tsunami progress in a chained or compound manner and to create new techniques for responsive disaster mitigation measures enabling society to recover. This special issue on disaster and big data consists of 11 papers detailing the recent progress of this project. As an editor of this issue, I would like to express our deep gratitude for the insightful comments and suggestions made by the reviewers and the members of the editorial committee.

Underground spaces have been variously used. Excluding underground floors of individual buildings, underground space in Japan is mainly used for streets, railways, and parking. Stores are often grouped along underground passages to underground railways and parking near main urban terminals. An accidental underground gas explosion at Shizuoka Station in 1980 led to disaster prevention measures in such spaces, forcing stricter safety standards. Following this was the 1999 Hakata underground mall inundation by the Mikawa River, which has further broadened the attention to the underground space and its inundation risk. Inundation damages in underground malls and spaces had occurred repeatedly since then, however, we believe that the 2012 inundation damage to underground spaces in New York city caused by Hurricane Sandy triggered further reviews of disaster prevention measures against underground spaces in Japan. Recently, small inundation damages often occurred in underground malls in Japan. With our praying these would not be prior events for possible large disasters, we publish this special issue considering that publishing disaster prevention measures and researches for underground spaces is increasingly important worldwide. This special issue features inundation damage caused by Hurricane Sandy, Japan’s law systems on antiflood measures in underground spaces, antiflood measures of the subway in Tokyo Metropolitan Area, current situations of antiflood measures in underground spaces. We would like to express our sincere thanks to those who contributed reports and research papers to this issue.