(2)The Nobi Earthquake (October 28, 1891, M 8.0)
The Nobi Earthquake occurred in a shallow land location and was one of the largest of this type. Its focal region was on the Nobi fault zone that extends into southern Gifu Prefecture (and includes the Neodani fault), and the Gifu-Ichinomiya fault zone. The seismic ground motion is believed to have corresponded to a seismic intensity of 6 in JMA scale in Gifu Prefecture, Aichi Prefecture, and eastern Shiga Prefecture, and a seismic intensity of 7 near the focal region (Fig.6-15). The earthquake could be felt over an area that ranged from Sendai to Kagoshima (Kagosima). It caused a total of 7,273 fatalities, and totally collapsed more than 140,000 houses. The damage was particularly extensive near the Neo Dani Valley in Gifu Prefecture, where nearly all the houses were collapsed (Fig.6-16 and Fig.6-17). Many landslides, cases of depression, ground fissures, and sand blows were seen in fields and mountainous areas near the focal region. One foreshock occurred on October 16 and four on October 25. There was offset of the earth's surface caused by faulting for a stretch of about 80 km north-northwest to south-southeast in the Nobi fault zone (Fig.6-18). This offset differed depending on the location, but was generally left-lateral strike-slip fault with dip-slip components. The maximum vertical slip was about 6 m, while that of the left-lateral strike-slip was about 8 m. This earthquake caused the discharge of hot spring to increase over a wide area.
As shown in Fig.6-19, the frequency of perceptible aftershocks decreased. The largest aftershocks were two of M 6.0 that occurred about four hours after the main shock and on October 30.
The Ministry of Education established the Imperial Earthquake Investigation Committee in 1892, the year following this earthquake. The Committee played a central role in earthquake study and research until the Earthquake Research Institute was established following the 1923 Kanto Earthquake.