昭和9年3月21日南伊豆強震調査報告

On Mar. 21, 1934, a strong earthquake occurred in the southern part of Idu Peninsula. The region in which damage was done, was limited within a small area containing a few villages. Seismic intensity near the epicentre was probably VIII in the Rossi-Forel scale. In the strongly shaken area changes in the hot-spring and in the earth electric current were occurred accompanied with the earthquake. There also occurred overturning, displacement and rotational motion of tomb-stone. The strong earthquake was accompained by detonative sound at some places in the northern part of the epicentre. The epicentre was determined from the datas of near-by stations, its position being situated at lat. 34°51'N, long. 138°55'E and depth 4km. 20 aftershocks were observed after the initial strong earthquake, some epicentres of these earthquakes were shown in Fig. 11. Pull-push distribution of intial earthquake motion was shown in Fig. 13