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[MZZ44-04] Comparison of the safety of shrines and temples in Akitsu town, Higashihiroshima city, Hiroshima prefecture: Suitability as evacuation sites during earthquakes
Keywords:Earthquake disaster, emergency evacuation site, shrine, temple
Higashihiroshima city in Hiroshima prefecture suffered extensive damage due to the heavy rain disaster of July 2018. Debris flow and river flooding occurred in most of the region. resulting in a total of 1,489 houses damaged, including 97 complete demolitions. Akitsu town, located in the southern part of Higashihirioshima city, experienced the highest number of these incidents, with a total of 556 cases (Higashihiroshima city, 2021). Akitsu town, situated along the Seto Inland Sea, is a region susceptible to heavy rain disasters caused by typhoons and storm surges, and is also at risk of tsunami damage in the event of earthquakes. Within Akitsu town, there are 32 designated evacuation centers, but only 10 of these are equipped to handle all types of natural disasters including earthquakes, landslides, floods, storm surges, and tsunamis, with a total capacity for 903 people. With a local population of 8,558 (as of Dec.2023), accommodating everyone in these shelters is challenging, and no safety evacuation areas have been established (according to the Higashihiroshima city website). Therefore, it is necessary to consider alternative emergency evacuation options in the event of a natural disaster.
In considering which locations are suitable for selection, we decided to compare the geographic safety of shrines, known for their 'safety hypothesis' in prior studies, and temples, which are being considered as new evacuation destinations. Many shrines that have been the subject of extensive research are located on slightly elevated ground, which has been noted to spare them from tsunami and flood damage (for example, Kuroki, 2022). On the other hand, temples are generally found to be in areas with a slightly higher risk of flooding compared to designated emergency evacuation centers. However, surveys indicate that they typically do not face a high risk of water disasters and are thus expected to function as evacuation sites (Kobayashi et al., 2023). In this study, we examined shrines and temples in terms of their safety as evacuation locations in the event of ground and landslide disasters, as well as tsunami disasters caused by earthquakes.
For the analysis, ArcGIS Pro 3.1.1 was used. The coordinates of 32 evacuation shelters, 22 shrines, and 13 temples within the Akitsu town area were extracted from Google Maps as point data. Using GIS data for the areas presumed to be flooded by tsunamis1), landslide warning areas2), and earthquake intensity assumption areas3), a comparative analysis was conducted on their respective locational safety. The analysis revealed that the shrines have generally been spared from disasters caused by rainfall, such as debris flows and floods, but that they located in areas that are susceptible to strong shaking from earthquakes, slope failures, and tsunamis. On the other hand, 11 out of 13 temples were deemed safe during the earthquake. Therefore, temples can be effective evacuation sites during earthquakes. Furthermore, when evacuation centers in Akitsu Town were analyzed using the same method, 16 out of 32 located in areas prone to strong shaking. Surprisingly, six of the 10 evacuation centers previously thought to be safe were found to be at risk of collapse during an earthquake.
In the Kazahaya district of the coastal town of Akitsu, local resident had previously set aside the north side of the railroad tracks on higher ground as an emergency evacuation site in the event of a tsunami. This was because it was considered difficult to secure a safe evacuation site. However, since the results of this analysis revealed that the embankment area is highly vulnerable to seismic tremors, they have begun to reconsider their evacuation site, including the option of evacuating to temples.
In considering which locations are suitable for selection, we decided to compare the geographic safety of shrines, known for their 'safety hypothesis' in prior studies, and temples, which are being considered as new evacuation destinations. Many shrines that have been the subject of extensive research are located on slightly elevated ground, which has been noted to spare them from tsunami and flood damage (for example, Kuroki, 2022). On the other hand, temples are generally found to be in areas with a slightly higher risk of flooding compared to designated emergency evacuation centers. However, surveys indicate that they typically do not face a high risk of water disasters and are thus expected to function as evacuation sites (Kobayashi et al., 2023). In this study, we examined shrines and temples in terms of their safety as evacuation locations in the event of ground and landslide disasters, as well as tsunami disasters caused by earthquakes.
For the analysis, ArcGIS Pro 3.1.1 was used. The coordinates of 32 evacuation shelters, 22 shrines, and 13 temples within the Akitsu town area were extracted from Google Maps as point data. Using GIS data for the areas presumed to be flooded by tsunamis1), landslide warning areas2), and earthquake intensity assumption areas3), a comparative analysis was conducted on their respective locational safety. The analysis revealed that the shrines have generally been spared from disasters caused by rainfall, such as debris flows and floods, but that they located in areas that are susceptible to strong shaking from earthquakes, slope failures, and tsunamis. On the other hand, 11 out of 13 temples were deemed safe during the earthquake. Therefore, temples can be effective evacuation sites during earthquakes. Furthermore, when evacuation centers in Akitsu Town were analyzed using the same method, 16 out of 32 located in areas prone to strong shaking. Surprisingly, six of the 10 evacuation centers previously thought to be safe were found to be at risk of collapse during an earthquake.
In the Kazahaya district of the coastal town of Akitsu, local resident had previously set aside the north side of the railroad tracks on higher ground as an emergency evacuation site in the event of a tsunami. This was because it was considered difficult to secure a safe evacuation site. However, since the results of this analysis revealed that the embankment area is highly vulnerable to seismic tremors, they have begun to reconsider their evacuation site, including the option of evacuating to temples.