The areas affected by the Great East Japan Earthquake of 2011 saw much residential mobility, causing a transformation of the urban areas. This study clarified the relationship between the reorganization of affected urban areas and the residential mobility in the affected prefectures of the Tohoku region. We analyzed characteristics of the prefectures by comparing national census data in 2010 with in 2015. The results are summarized as follows:
Changes in the regional structure and residential mobility are related to each other. Although this relationship affects the disaster-stricken areas, the mobility that occurs due to disasters is caused by unexpected physical and psychological damages. The movements must be determined in a short span of time with uncertain information, thereby being easily influenced by vague regional images and reputation, and taking the form of a collective mobility by the group with high anxiety. Similarly, in the case of the Great East Japan Earthquake, many movers decided to shift to a new address in their own municipalities or neighboring municipalities that were not far from the previous residence.
Among the affected prefectures of the Tohoku region, Iwate Prefecture, especially, saw many such movements. The inhabitants had formed a small living area in a narrow plain on the coast. Spatially, its area was not very contiguous with other living areas formed in the neighboring municipalities. Therefore, in some municipalities, more than 60% of inhabitants who moved after the earthquake selected a new address within their own municipality. As a result, corresponding to city planning with respect to disaster prevention, the shape of the urban area was transformed toward the inland direction. In Miyagi Prefecture, in addition to moving within the daily living area, mobility to Sendai City dominated, which is the prime city in the Tohoku region. Miyagi Prefecture’s disaster-stricken areas have higher population density than Iwate Prefecture’s. Small- and medium-sized municipalities in Miyagi alone could not have kept up with the rapidly increasing demand for housing. As a result, people who did not get a new residence in the previous neighborhood showed preference for Sendai, which has plenty of available housing. On the other hand, in Fukushima Prefecture, the rise and fall in the population due to the nuclear accident was remarkable;the mobility observed there greatly went beyond the daily living area. This is because those movements occurred on the basis of evacuation orders and impacts on health. In some towns and villages where the whole population was evacuated, the urban area itself disappeared for several months to several years.
This paper reports the transitions in urban structure for Urban Employment Areas （UEAs） in Japan by using municipal and 1 km-grid population data from 1980 to 2015. UEAs consist of central and suburban municipalities, and UEAs are categorized based on the population changes in each by applying the Klaassen’s method.
In 1980s and 1990s, many UEAs in Japan experienced urbanization and suburbanization. In these decades, the largest cities showed the tendency of decentralization. However, after 2000, most UEAs showed the tendency of centralization, especially among the small-sized UEAs. This result was different from the hypothesized transitions of Klaassen’s urban life cycle model, lacking the deurbanization phase.
In Japan, a clear positive correlation in population size and growth has emerged as economic and social changes have proceeded, such as changing industrial structure and the declining birth rate and aging. Smaller UEAs are experiencing population decline earlier than larger UEAs along with the decrease in the total population in Japan. As the population of larger UEAs are also likely to decrease in the near future, there is plenty of possibilities that larger UEAs will also centralize following the same structural change that smaller UEAs have recently experienced.
Because of the shift to automobile traffic and the decrease in the users, the rail line abandonments have been occurred mainly in the rural areas in Japan. In addition, there are some existing rail lines which are planned for their future abandonments. The number of rail lines that will be difficult to be maintained by railway companies will increase further in the rural parts of Japan. This study retrospectively assessed the possible impacts of rail line abandonments on the temporal changes in population and income levels in local governments along the abandoned rail lines by using regression models. The results of the analysis indicated that the high population decline rates observed in the region where rail lines have been abandoned were not accelerated by the rail line abandonments. We obtained a similar finding about impacts on income-level changes indicating no statistical differences of average annual changes of income per capita between before and after the railway abandonments, as well as between the regions where rail lines have been abandoned and those where rail lines have been maintained throughout the study period.