Abstract
We examined tide gauge records at stations in and around the Kui peninsula to find if a precursory crustal deformation occurred before the 1946 Nankai earthquake. First, we removed effects of atmospheric pressure and astronomical tide on the records. Then, we tried to get rid of the effects of the oceanic current by taking the difference of the records betweentwo stations. After these corrections we found that sea level at Uragami where is located on the southeastern coast of the Kui peninsula had risen about 10 cm just before the Nankai earthquake. The sea level change, if we consider that to represent real subsidence of land near Uragami, could be explained by supposing that a slow fault slip corresponding to moment magnitude 6.9 occurred on the plate boundary in the offing of southeast of the Kui peninsula near the hypocenter of the Nankai earthquake.
