[O-08] Poster presentations by senior high school students

[O08-P52] Relationship between the location of Shrines and Tsunami in Asahi City, Chiba Prefecture

*Akito Suenaga¹ (1.Ichikawagakuen Ichikawa high school)

Keywords:Tsunami, Shrine, The 2011 off the Pacific coast of Tohoku Earthquake

The relationship between the distribution of shrines and the location of tsunami arrival has only been studied in a few areas of Japan, and the areas which have been studied are limited. In Chiba Prefecture, especially in the Sotobo region, there have been many tsunamis, such as the Tohoku Pacific Ocean Earthquake and the Genroku Earthquake. On that basis, we selected Asahi City, one of the municipalities in Chiba Prefecture that was severely affected by the tsunami caused by the Tohoku Pacific Ocean Earthquake, as this study’s area. In addition, the reconstruction memorial monument at Sengen Shrine in the Iioka district of Asahi City states that the shrine was enshrined after suffering repeated tsunami damage from the Genroku and Hoei earthquakes. Therefore, we focus on the Iioka area of Asahi City because it is considered to be an area where the connection between shrines and tsunamis has been strong since the Edo period. To the study, we used municipal histories and Google Maps to research the names, deities, construction dates, and locations of shrines, and plotted them on a Geospatial Information Authority of Japan map on the Web. In addition, tsunami inundation area data from the Tohoku-Pacific Ocean Earthquake was overlaid on the map to examine the tsunami arrival location and area. The above data were then used to compare the relationship between shrines and tsunami arrival locations (Fig. 1). Furthermore, regarding the tsunami caused by the Genroku Earthquake, one of the earthquakes that led to the construction of Sengen Shrine, the Policy Office, Disaster Prevention Policy Division, Disaster Prevention and Emergency Management Department, Chiba Prefecture, shows the potential tsunami inundation area by simulating that earthquake on its websiteTherefore, in this study, we used the data as the tsunami inundation area at the time of the Genroku Earthquake and compared it with the location of shrines in the Iioka area, along with the tsunami inundation area of the Tohoku Pacific Offshore Earthquake. (Fig. 2) As a result, it was found that in the Iioka area, shrines stand in a line at the tsunami arrival point of the Tohoku-Pacific Ocean Earthquake in a place where there are no notable topographical ups and downs. The above mentioned Sengen Shrine was found to almost overlap the tsunami arrival locations of both the Genroku and Tohoku earthquakes. And since the other shrines located near the tsunami arrival point of the Tohoku earthquake were built later than the Sengen shrine and are a little farther away from the tsunami arrival point of the Genroku earthquake, it can be assumed that they were built on the basis of the Sengen shrine and the tsunami arrival point of the Genroku earthquake. On the other hand, shrines around the Iioka area that were in the inundation area of these tsunamis had had their precincts raised and mitigate tsunami damage. Therefore, it can be considered that there is a high level of tsunami awareness, especially in the Iioka area and its vicinity. As well, many of the shrines built in the coastal areas of Asahi City were found to have escaped from tsunami damage from the Tohoku-Pacific Ocean Earthquake. Consequently, shrines not only provide a safe place against tsunamis, but also have the role of pointing out safe areas and some shrines shown the locations where past tsunamis have come, which is very important from a disaster prevention perspective.