Abstract
Assuming that building damage caused by the Hanshin-Awaji Earthquake was due not only to the strength of the quake but also to the social and physical environment, the author investigated the varying scale of building damage related to tenure type of the land and houses. The study also aimed to examine why housing damage was concentrated in the inner-city area. This study is based on the author's field work of damage inspection and on the analysis of both official statistics and registry records of land and houses. The results are summarized as follows:
1) A clear difference building damage was found based on the tenure of land and houses: noncollapsed or slightly damaged houses totaled 29.1% of “owner-occupied freehold” houses, but only 2.2% of “rented” houses.
2) The older the buildings were, the higher the rate of damage: 81.1% of houses built before 1959 were completely collapsed. On the other hand, only 13.0% of houses built after 1980 collapsed.
3) Buildings with smaller ground floor space suffered more serious damage: 79.2% of buildings of less than 30 square meters were completely collapsed.
4) Building structure was also related to the damage : more than 90% of dwellings in the study area consisted of wooden houses, of which 70% were completely collapsed. Of wooden houses, however, only 20% of buildings constructed after 1980 were completely collapsed. Because most steel frame and reinforced concrete structures were built in the past two decades, they did not collapse or were only slightly collapsed.
5) The damage ratio of old rented houses was higher than that of owner-occupied freehold houses.
6) Regardless of ground floor space, the ratio of completely collapsed houses was higher among rented than among owner-occupied freehold houses. This tendency was more noticeable among houses with large ground floor space.
7) The proportion of small buildings was higher in the category of rented houses than in the owner-occupied freehold category.
8) The larger the ground floor spase, the lower the ratio of old buildings: most buildings with less than 30 square meters of ground floor space were built before 1959. Less than 50% of the buildings with 40-50 square meters were built before 1959, although the ratio of old buildings was higher in the category of larger houses (50 square meters or more). New buildings and rebuildings were mainly found in the 40-50 square meter category. This suggests that (a) the earthquake caused moredamage in the category of small, old houses, most of which were rented houses, and (b) medium-sized houses were newly built or rebuilt in the past 20 years, which mainly comprise the owner-occupied freehold category.
9) Individual rebuilding of small, old houses is difficult, because most are located in the physical environment of small sites along narrow streets less than 4 meters wide. The most typical small, old buildings are tenement houses, which comprised 80.1% of all houses before 1959 and 86.6% of houses with a floor space of less than 30 meters.
10) Until the end of the Taisho era, the study area had been developing into residential quarters for workers, which mostly consisted of small rented houses. Most of these rented houses continued to exist in densely built-up environment of the inner area of Kobe until the earthquake, sinse many parts of this area were not affected by the air raids of World War II.
11) After the war, house and land ownership became progressively more fragmented because of the constant increases in taxes. This fragmentation has mainly led to a change from rented houses, to owner-occupied freehold houses, leading to a very complex ownership pattern. This is one of the main factors that put a brake on the renewal process.
12) One of the reasons for the delay in the renewal process is that most of the small, old houses were occupied by long-term elderly residents.
