Approach and Views of The Studies For Disaster Prevention in Urban Areas

この記念号で、筆者は自身とセンターを中心とする都市防災研究の過去、現在、将来について書くことを志した。だが、それらをまとめることは筆者の手に余った。また、過去については本誌38号でそれをかなり紹介したつもりである。そこで、この小文では自分史を中心に、また筆者が現在考えていること、ならびに現在進めている研究、計画している研究を紹介することにした。筆者が地域(都市)地震防災を手がけて、もはや本年で29年になる。その手始めは1964年新潟地震の調査や、河角学説に基づく東京都防災会議・地震部会の設置などに伴う防災行政調査・研究の開始とそれへの参加等であり、そのような環境下でのエリアの地震防災に向けて今日まで、その途を歩んできた。地震防災学は基本的に経験の学問である。それ故筆者は災害現場で可能な限り将来の災害対策への教訓を学んできた。そのとき、行政の防災調査・研究は筆者にとって常に大きなバネとなってきた。被害想定や地域危険度測定で筆者が手がけた事項で実証的・科学的でない課題への答を災害現場に求め、それを理論的にも検証することをモットーとしてきた。かくして建築の耐震工学から、やっと最近地震工学さらには地域(都市)地震防災学へと途を広げてきた。それは、古い・やや古い地震を追跡すること、それを近代地震学の手法でフォローすることなどで大きな成果を挙げてきたと自負している。そのようなプロセスを経て、災害時の人間行動や死傷に至るプロセスの調査研究、また海外調査研究を開始するとともに災害社会学とも呼ばれる分野へもアプローチするに至った。現在は、企業の防災力を如何にしたら高められるかに重大な関心を持っている。それには多分「防災経済学」なる分野での研究の展開が必要不可欠である。東京を守るために。それこそが筆者にとっての都市防災研究の目標である。This paper has eight chapters as summarized below. 1. Social trends related to earthquake disaster prevention and studies on disaster prevention conducted by the Center for Urban Studies Both the rise of earthquake disaster prevention as a social issue and the development of earthquake disaster prevention have been step-by-step processes. There have been two major events in this process. The first was in 1964，when the kawasumi Theory was announced. This theory，well-known abroad，states that major earthquakes hit the Tokyo Metropolitan Region every 69 years plus/minus 13 years. In the same year the Niigata Earthquake occurred. Building codes were amended to enable the construction of high-rise buildings 31 meters and taller. It was the first year of the author\u27s 28-year carrier of studying the issue of disaster prevention. He conducted a survey of the Niigata Earthquake and was given an opportunity to participate in a survey initiated by the Tokyo Metropolitan Government. Another year of significance was 1978. Two years earlier，Katsuhiko Ishibashi，then an assistant of the University of Tokyo，announced a theory on the probability of the Tokai Earthquake. His theory became a focus of media attention，and even forced the Japanese government to take action. The government set up The Central Disaster Council，chaired by the Prime Minister，and enacted the Large-Scale Earthquake Countermeasures Act in 1978. This was also the year of the Izu-Ohshima Kinkai Earthquake and the Miyagi-ken-Oki Earthquake. The Center for Urban Studies of the Tokyo Metropolitan University was established in 1977. It immediately began a project research titled Comprehensive Studies on Earthquake Disaster Prevention. This project research was expanded to a large-scale project in 1990 and renamed the Comprehensive Studies of Optimum Disaster Prevention Systems. The author has been a key figure in both projects. 2. Outline of the author\u27s surveys and studies on earthquakes The author conducted a comprehensive survey on all major earthquakes which occurred in Japan，from the 1964 Niigata Earthquake to the 1993 Kushiro-oki Earthquake. The results have been utilized by governments of all levels for regional earthquake damage estimations and for area assessments of earthquake vulnerability. 3. Research on Seismic Microzonation Seismic microzonation is the study on ground conditions of the target area，which serves as the basis for regional earthquake damage estimations，area assessments of earthquake vulnerability，and assists in the study of the seismic risk potential based on seismicity. We have conducted research on the past surveys and records of earthquakes both in Japan and overseas using methods and techniques of modern seismology and earthquake engineering. 4. Urban Facilities Survey and Systematic Understanding of Asseismicity We have established a method to estimate earthquake damage through estimating the earthquake resistance of individual urban facilities and groups of urban facilities. 5. Human behavior and casualties in disasters We have conducted an extensive survey on how people react when an earthquake or fire occurs and how their actions lead to casualties and have proposed methods to estimate the number of casualties and to reduce damage. 6. Survey on measures against disasters taken by urban communities and social effects of disasters We have conducted a survey on steps taken by households，communities，companies and governments to find out how ready these groups are to face a disaster. We also proposed issues to be addressed in the future. We have also conducted cased studies on social and economic impacts of disasters and proposed research methods to be applied to future studies on disasters. 7. Research on surveys on disasters conducted abroad and international comparison of vulnerability to disasters We are now conducting an on-the-spot survey of disasters abroad to compare major cities around the world in terms of their vulnerability. We are also studying disaster prevention systems used in other countries and the social and economic conditions of these nations. We have reported some of our findings already. 8. Advice to companies for disaster prevention The functional overconcentration in Tokyo has gone so far that people are apt to think that “If Chiyoda-ku is destroyed，the whole of Tokyo will be destroyed and eventually the whole nation will be destroyed.” Making Tokyo Metropolitan Region more disaster resistant is of importance not only to Japan but for the rest of the world. As Tokyo is driven by the companies within its borders，corporate efforts to minimize damage will help Tokyo recover smoothly after a catastrophe. This paper，therefore，concludes by emphasizing that companies do more to help in disaster prevention