Society is aging rapidly in Japan. For disaster mitigation against periodic earthquakes based on asperity theory in seismology, the transition of the social environment should be considered in the intervals between periodic events. This paper focuses on the aging of society as an important expansion factor in human injury. The major objective of this paper is to estimate the effects of aging on injury including serious cases caused by earthquakes. In this paper, three age classes are used as follows. Young age is defined as the generation under 14 years. Old age is defined as 65 years old or over. Middle age is defined as the other group. This classification is often used by the census.
  Sendai City as the Miyagi prefectural capital is selected because it is one of the most earthquake-prone regions in Japan. The main earthquake to hit the region is the Off Miyagi earthquake with a magnitude about 7.5 Mj. This event has periodically struck Sendai City at average intervals of about 37 years.
  A few assumptions are made in estimating the injury rate as a result of an Off Miyagi earthquake without a tsunami. Firstly, the normalized injury ratio proposed by the authors can be applied to estimate the injury rate for a foreseen earthquake. Secondly, the injury rate in each age class as a result of an expected Off Miyagi earthquake can be assumed to be the same as in the previous event in 1978. Finally, only the transition of the population structure regarding multiple factors can be considered in the interval between periodic events. In addition, the emergency response load of taking care of the injured elderly is proposed.
 (1) In the subject region in Sendai City, the ratio of the old-age population divided by the total population has increased three and half times in the 30 years from the previous Off Miyagi Earthquake in 1978.
 (2) The normalized injury ratio in the old-age class was evaluated as being two and half times that in the middle-age class.
 (3) The percentage of injured in the subject region in each age class during the Off Miyagi Earthquake in 1978 was reproduced.
 (4) Under the assumed occurrence of the expected Off Miyagi earthquake in 2005, the number of injured in the subject region in each age class was estimated considering the increase in the population and the progress of the aging of society. The number of injured has increased five times in the past 30 years. The year 2005 was adopted as the assumed occurrence year of the earthquake because the fiscal year of the newest data that have already been published as population statistics of the census was 2005 at this submission.
 (5) The emergency response load of taking care of the injured elderly was evaluated. The load of the middle age has increased approximately three times in the past 30 years.

抄録全体を表示

  The process of failure propagation of masonry buildings during earthquakes is simulated using a refined version of the distinct element method that simulates three-dimensional elastic, failure, and collapse behaviors of structures. Models with a flat roof and models with a vault roof are considered, and their failure propagation mechanisms are examined. The influence of the direction of the input ground motion on failure propagation is also investigated. Moreover, the effectiveness of three reinforcement measures is compared. One measure is increasing the mortar strength, the second is increasing the thickness of the bearing walls, and the third is introducing wooden columns and beams. Among these measures, increasing the mortar strength is found to be the most effective. Increasing the thickness of the bearing walls and introducing wooden columns and beams are found to be effective only if the roof has sufficient integrity since the collapse of the roof depends on the integrity of the bearing walls and the roof itself.

抄録全体を表示

  This study developed a numerical formula based on statistical data on collapsed, burnt down buildings, and refugees taking shelter in schools during the Great Hanshin Earthquake of 1995. The data on building damage used in the study were 2004 municipalities, classified into 46 junior high school districts. The independent variables were collapsed buildings, burnt down buildings, and average population of each building. The refugee population was regarded as a dependent variable in this study. The formula effectiveness in the junior high school district was 63% and 98% in administrative wards. When predicting the refugee population in schools in Kobe City using the formula, the school refugee population was 80% of all refugees in Kobe City predicted by the Hyogo Prefectural Government. This outcome was the same percentage of the population in school refuges in the Great Hanshin Earthquake. Predicting the refugee population who took shelter in other places besides school refuges and controlling other effective intermediary variables to fit different local areas are issues worth pursuing in advanced research.

抄録全体を表示

  Risk communication is considered as an important step of risk management process. An appropriate risk communication needs holistic learning, facilitation between the information sender and receiver, and trust. The paper proposes a new method of risk communication emphasizing the trust building with the local communities through communicative survey. Applying the method in Nagata elementary school, the paper provides a case example with illustration and analysis on useful communicative survey, and exemplifies the shelter planning (shelter location and residents' assignment) process. The participants' ideas and their opinions are best used to adaptively modify and eventually reach the most appropriate assignment plan. It is argued that the process builds trust in the risk information and enables residents to take decisive actions.

抄録全体を表示