RSP stations on Rangiroa, Tubuai, and Rikitéa recorded acoustic waves (T-phase) from a strong submarine volcanic eruption in the vicinity of the Izu Islands. Between 25 March and 30 April, more than 500 signals were received, 300 between 2 and 9 April. Most of the events were impulsive and of short duration, indicating explosive volcanic activity at a shallow depth. Some of the events were emergent and of longer duration indicating quiet emission of lava. J.M. Talandier noted that these events appear to be correlated with the submarine activity reported in 9:2.

Geological Summary. A submarine eruption was observed in 1984 from Kaitoku Seamount (Kaitoku Kaizan), a three-peaked submarine volcano 130 km NNW of Kita-Iojima. A submarine eruption had previously been reported in 1543 from a point about 40 km to the SW, which the Japan Meteorological Agency attributes to Kaitoku.

Information Contacts: J. Talandier, Lab. de Géophysique, Tahiti.