2020 Volume 85 Issue 775 Pages 1955-1963
In the past earthquake disasters, a large number of people trapped in collapsed buildings occurred, and prompt rescue operations were required to increase the survival rate. The occurrence of large-scale earthquakes in the future is a concern in the metropolitan area. For example, in the damage assumption by the Southern Tokyo In-land Earthquake, it is said that the maximum number of people expected to be trapped in collapsed buildings due to structural damage from shaking is about 72,000 in the total affected areas. Therefore, disaster mitigation measures according to the local situation are urgently needed. However, in many local governments, earthquake damage assumptions are limited to calculating the number of people who are trapped in collapsed buildings. In addition, qualitative discussions are central to status of rescue activities after an earthquake.
In this study, we evaluated the disaster mitigation effects of rescue activities that consider regional characteristics such as building and road conditions, locations of fire stations, and the number of firefighters in Yokohama City, Kanagawa Prefecture. In evaluation, we used indicators such as the time required for rescue operations and number of people rescued over time.
First, we proposed a method for evaluating the disaster mitigation effects of rescue activities based on regional characteristics. In this study, it was assumed that firefighters carried out rescue activities for those who are trapped in wooden or non-wooden collapsed buildings by shaking when the earthquake occurred at 5 am. The proposed evaluation method aims to be easily applicable to other local governments by utilizing the public data such as government statistics.
Next, we clarified how much time it takes to rescue people who are trapped in collapsed buildings using the proposed evaluation method. As a result, the difference in rescue completion time in each region was a maximum of 3.8 hours in the case of intensity of lower 6 on the Japanese scale (instrumental seismic intensity: 5.6), a maximum of 18.9 hours in the case of intensity of lower 6 (instrumental seismic intensity: 5.8), and a maximum of 63.8 hours in the case of intensity of upper 6 (instrumental seismic intensity: 6.0). Based on the above results, it became clear that as the seismic intensity increases, the difference in time required for rescue operations between regions tends to increase. In addition, when a large scale disaster, it was suggested that rescue teams are easily affected by road blockages when moving around the activity site in areas where there are many old earthquake-resistant wooden buildings and widely distributed.
The method proposed in this study is effective when comprehensively considering earthquake disaster countermeasures because it can evaluate the disaster reduction effects of structural measures such as repair of old buildings and non structural measure such as the arrangement of firefighters. Furthermore, the evaluation method can be expected to encourage local residents to understand earthquake disaster countermeasures such as the removal and repair of old buildings by local residents recognizing the current situation of regional characteristics in consideration of the rescue operation ability.
