16. Regional Differences in Iwate Prefecture Road Usage Recovery Following the 2011 Tohoku Earthquake

In a previous study, we calculated the usable road distance in the Southern Coastal area of the Iwate Prefecture following the 2011 Tohoku Earthquake. In this context, a usable road is one on which at least one vehicle was detected during the observation period. If the cumulative usable distance percentage up to September 30, 2011 is considered to be 100 %, then the percentage of the usable road distance determined by April 8, 2011 and April 29, 2011 was 80 % and 90 %, respectively. In this study, we calculated the regional differences in the road recovery in the Iwate Prefecture following the 2011 Tohoku Earthquake. Therefore, we divided the Iwate Prefecture into four areas, i.e., the Northern Inland, Southern Inland, Northern Coastal, and Southern Coastal areas. The primary results of our study are as follows. First, we determined that for both the northern and Southern Inland areas, 80 % of the road distance was usable by April 15, 2011 and 90 % was usable by May 27, 2011, which indicates that the recovery speed in both the northern and Southern Inland areas have been slightly slower than that in the Southern Coastal area. Second, we found that for the Northern Coastal area, 80 % of the road distance was usable by April 29, 2011 and 90 % was usable by June 24, 2011, which implies that the recovery speed in the Northern Coastal area has been extremely slower than that in the Southern Coastal area. We assume that the recovery difference between the northern and Southern Coastal areas has been caused by differences in their geographical features.