Anomalous phenomena precursory to the 1891 Nobi earthquake of magnitude 8.0 are collected mostly based on the existing results of the enquiry investigation conducted soon after the earthquake. Precursor data amounting to 202 in number become available along with their precursor times. They are rumbling or detonation, anomalous animal behaviour, earthquake light, changes in underground water/hot springs and so on.
It appears that the number of earthquake precursor tend to increase at about 100 days before the main shock. About 10 days preceding the shock, the increasing rate becomes much accelerated reaching a frequency peak having a precursor time of 1 day or so. Such a tendency of precursor appearance is much the same as that for the 1923 Kanto, 1944 Tonankai and 1978 Izu-Oshima Kinkai earthquakes although slight differences may be observed. The tendency that the number of precursor decreases as the distance between the epicenter and an observation spot increases is also confirmed.
In light of these precursors detected by human sense in association with the Nobi earthquake as well as other large earthquakes in Japan, attention should be paid to precursors of this class along with geophysical precursors in future earthquakes.
