2015 年 68 巻 4 号 p. 107-124
The 1854 Ansei Nankai Earthquake caused widespread damage from Kii peninsula to Kyushu region with Japanese seismic intensities of V to VI. A large amount of descriptions related to this earthquake are found in the archives “New Collection of Material for the History of Japanese Earthquakes”. The no. 5 of supplements to vol. 5 has collected documents related to the Ansei Tokai Earthquake (Nov. 4th, Ansei 1 in the old (lunisolar) calendar, or Dec. 23rd, 1854 in the new (Gregorian) calendar), Ansei Nankai Earthquake (Nov. 5th), and the largest aftershock in the Bungo channel (Nov. 7th), whose total number of pages amounts to 2,528. These collection books have quoted from many historical documents published by local governments, and reprinted from original historical material related to the earthquakes. However, when the published books were used, no reprint of original material was made. Purpose of this study is to reprint photocopy of an original private record handed down to Warabioka family who was a head of Masaki village of Ainan-town in the southernmost of Ehime Prefecture in Southwestern Japan. Furthermore, we compare our reprinted text with published ones, and make detailed investigation on natural phenomena and damage by the Ansei Nankai earthquake. It is identified that a lack of description about natural phenomena and damage and an error of the number of the dead in the texts adopted in the “New Collection of Material for the History of Japanese Earthquakes”. In particular, it is clear that the number of the dead in Fukaura village is not 101 but only one. This is consistent with the record of the necrology and gravestone. Preliminary estimation for the crustal deformation indicates a lowering of groundwater level in Masaki region by volume dilatation associated with the earthquake. This result is consistent with the record that the groundwater level was lowered. Furthermore, we compared our reprinted text with seven historical documents of Uwajima-Date family who had governed this area at that time in order to know the difference of information in the historical documents of the two families. As a result of comparison, there is no contradiction about descriptions of tsunami damage. However, the comparison shows no description about inland natural phenomena and damage such as well water dried up and rock fall in the historical documents of Uwajima-Date family, whereas it is written in the record of Warabioka family. These results show that the private record written by the village head has also valuable information on the earthquake.