Abstract
The main points of this paper are as follows:
1) The origin and mechanism of the pre-erup tion earthquakes and eruption tremors are discussed.
2) The relation between maximum amplitude and frequency distribution of isolated eruption tremors and A-type volcanic earthquakes are discussed.
3) The pre-eruption earthquake have occurred at many former eruptions. The occurrence time of the pre-eruption earthquake and of the eruption are discussed.
4) The origin of the A-type volcanic earthquakes and the relation between the swarm period of those earthquakes and the period of eruptions are discussed.
5) The devi a tion of seismic ray at Izu-Oshima Island and the reason for it are discussed.
