1433 (永享5) 年会津地震 (M6.7) の非実在性

抄録

TOKYO ASTRONOMICAL OBSERVATORY (1981) and USAMI (1975) are listing a historical destructive earthquake of magnitude 6.7 that occurred in the Aizu province in northeast Japan on November 7, 1433. However, the only basis of the earthquake is the total collapse of the Todera-Hachimangu Shrine due to violent earthquake motion which is described in an old book named “Todera-Hachimangu Ryakki Nagacho”. In this paper reliability of the description has been examined and unreality of the earthquake has been concluded.
“Todera-Hachimangu Ryakki Nagacho” is a compiled material written more than 150 years after 1433 and, so, the reliability of its description on older times is generally low. On the other hand, there is another historical document concerning the Todera-Hachimangu Shrine called “Todera-Hachimangu Nagacho”, which is a yearly record mainly on the shrine's ceremony and local happenings written year by year. Its original copy covering most part of the period between 1350 and 1635 is preserved in the shrine. This is the most reliable and basic material concerning the Todera-Hachimangu Shrine and its vicinity for the 14th to the 16th centuries.
In “Todera-Hachimangu Nagacho” there is no record about the collapse of the shrine in 1433. On the contrary, it contains a few reliable descriptions which conflict with seismic disaster in the province at that time. Thus, the collapse of the shrine due to an earthquake in 1433 has proved to be not an actual fact. Therefore, the 1433 Aizu earthquake of magnitude 6.7 should be deleted from Japanese historical earthquake catalogs.