1:45 PM - 3:15 PM
[O08-P83] A study of the landslide disaster hazard map for tourists in Oshima town, Tokyo
Keywords:Landslide disaster, hazard map, Izu Oshima island
I. Research background
From December 25 to 26, 2023, I participated in fieldwork in Izu Oshima Geopark. In that time, we saw the hazard map for the first time as visitors and thought that it lacked information on where we should evacuate to, and which locations were dangerous. Therefore, we made an easy-to-understand hazard map for tourists visiting Oshima.
We mapped the tourist attractions and landslide evacuation sites listed on the official Oshima town webpage onto Geographical Survey Institute maps, and then used Google Maps' route search to find the nearest evacuation site to each tourist attraction, in terms of time and distance.
II. Research Methods
First, we created a hazard map by overlaying gradient maps of evacuation centers, tourist attractions, and areas at risk from landslides in Oshima town. The Association for the Promotion of Crisis Management (2021) states that "the distance that children and the elderly can travel on foot without difficulty is generally estimated to be up to 2 km. Because Oshima town has many areas with larger slopes than the 23 wards of Tokyo, it is considered likely that an evacuation would take more time. Therefore, we listed tourist attractions that are more than 1.5 km from the nearest evacuation center. Second, the Maps from each tourist attraction to the nearest evacuation site were calculated using Google Maps. Third, we visited Oshima town for fieldwork and conducted a survey by walking along the evacuation routes.
III. Results
Of the 22 tourist destinations surveyed, 11 were located far from evacuation centers. In addition, six of the tourist destinations with evacuation centers far from the evacuation sites were included in the areas at risk of dangerous torrents, debris flow, steep slope failures, and mudslides as indicated in the "Overlapping Hazard Map", these destinations included were the stratum section, Hinodehama Beach, Akinohama Beach, Izu Oshima Volcano Museum, Tsubaki-hana Garden, and Tokyo Metropolitan Oshima Park. Therefore, we consider it necessary to inform tourists before visiting these tourist attractions. Comparing the areas where landslides caused by Typhoon No. 26 occurred in 2013 with other areas in Oshima Town, we found no significant differences in the risk of steep slope failures and mudslides.
From the study, it was found that about half of the tourist destinations in Oshima Town are more than 1.5 km from the nearest evacuation center. This indicates that there are many tourist destinations where evacuation is likely to be difficult in the event of a landslide. It was also found that there are many places that are at risk of being affected by mudslides and other damage similar to a landslide that occurred in 2013. Especially the Izu Oshima Volcano Museum and Tsubaki-hana Garden in Motomachi, Oshima, have a high risk of mudslides and the shortest distance to evacuation centers is over 1.5 km.
IV. Discussion
This study was initiated by the belief that existing hazard maps do not indicate the nearest evacuation centers from each tourist site or the specific routes to them, which would hinder quick evacuation. In order to help everyone on the island, including not only island residents but also tourists, to evacuate quickly, we made a hazard map that includes evacuation routes, locations of block walls that may fall and block roads, narrow roads that are difficult for many people to pass, and expected human movements based on the number of tourists visiting each tourist attraction.
In addition, since tourists visiting Oshima town are often less familiar with the land and have no one to rely on other than local residents, they should understand in advance the nearby evacuation centers and routes to them, and confirm the risk of landslides in the tourist areas they visit and the nearest evacuation centers. However, it is difficult and impractical for all tourists to voluntarily check evacuation centers and routes before sightseeing. Therefore, we should make efforts to show evacuation centers and routes to as many tourists as possible. For example, we suggest posting Oshima's landslide hazard map in terminals, on ships, and at tourist spots on the island, and making the landslide hazard map available online.
From December 25 to 26, 2023, I participated in fieldwork in Izu Oshima Geopark. In that time, we saw the hazard map for the first time as visitors and thought that it lacked information on where we should evacuate to, and which locations were dangerous. Therefore, we made an easy-to-understand hazard map for tourists visiting Oshima.
We mapped the tourist attractions and landslide evacuation sites listed on the official Oshima town webpage onto Geographical Survey Institute maps, and then used Google Maps' route search to find the nearest evacuation site to each tourist attraction, in terms of time and distance.
II. Research Methods
First, we created a hazard map by overlaying gradient maps of evacuation centers, tourist attractions, and areas at risk from landslides in Oshima town. The Association for the Promotion of Crisis Management (2021) states that "the distance that children and the elderly can travel on foot without difficulty is generally estimated to be up to 2 km. Because Oshima town has many areas with larger slopes than the 23 wards of Tokyo, it is considered likely that an evacuation would take more time. Therefore, we listed tourist attractions that are more than 1.5 km from the nearest evacuation center. Second, the Maps from each tourist attraction to the nearest evacuation site were calculated using Google Maps. Third, we visited Oshima town for fieldwork and conducted a survey by walking along the evacuation routes.
III. Results
Of the 22 tourist destinations surveyed, 11 were located far from evacuation centers. In addition, six of the tourist destinations with evacuation centers far from the evacuation sites were included in the areas at risk of dangerous torrents, debris flow, steep slope failures, and mudslides as indicated in the "Overlapping Hazard Map", these destinations included were the stratum section, Hinodehama Beach, Akinohama Beach, Izu Oshima Volcano Museum, Tsubaki-hana Garden, and Tokyo Metropolitan Oshima Park. Therefore, we consider it necessary to inform tourists before visiting these tourist attractions. Comparing the areas where landslides caused by Typhoon No. 26 occurred in 2013 with other areas in Oshima Town, we found no significant differences in the risk of steep slope failures and mudslides.
From the study, it was found that about half of the tourist destinations in Oshima Town are more than 1.5 km from the nearest evacuation center. This indicates that there are many tourist destinations where evacuation is likely to be difficult in the event of a landslide. It was also found that there are many places that are at risk of being affected by mudslides and other damage similar to a landslide that occurred in 2013. Especially the Izu Oshima Volcano Museum and Tsubaki-hana Garden in Motomachi, Oshima, have a high risk of mudslides and the shortest distance to evacuation centers is over 1.5 km.
IV. Discussion
This study was initiated by the belief that existing hazard maps do not indicate the nearest evacuation centers from each tourist site or the specific routes to them, which would hinder quick evacuation. In order to help everyone on the island, including not only island residents but also tourists, to evacuate quickly, we made a hazard map that includes evacuation routes, locations of block walls that may fall and block roads, narrow roads that are difficult for many people to pass, and expected human movements based on the number of tourists visiting each tourist attraction.
In addition, since tourists visiting Oshima town are often less familiar with the land and have no one to rely on other than local residents, they should understand in advance the nearby evacuation centers and routes to them, and confirm the risk of landslides in the tourist areas they visit and the nearest evacuation centers. However, it is difficult and impractical for all tourists to voluntarily check evacuation centers and routes before sightseeing. Therefore, we should make efforts to show evacuation centers and routes to as many tourists as possible. For example, we suggest posting Oshima's landslide hazard map in terminals, on ships, and at tourist spots on the island, and making the landslide hazard map available online.