JMSA [and JMSDF have] continued frequent monitoring flights over several known submarine volcanoes (table 1). Discoloration has been seen occasionally over Fukujin each year since 1977. Analysis of Landsat satellite multi-spectral scanner data revealed discolored water there in January 1982, after a year of quiescence.

Table 1. Volcanic activity at three sites in the Volcano Islands, January 1978-December 1982, detected by JMSA and JMSDF monitoring flights. Activity indicated as D = Discolored water; N = No discolored water, - = No overflight, ? = not reported. This table combines data from 4:7, 5:4, 5:11, 5:12, 6:10, and 7:9, plus additional 1982 data not published in the Bulletin.

Geological Summary. Fukujin seamount in the Mariana Volcanic Arc has risen on occasion to just beneath the ocean surface. Intermittent periods of water discoloration have been observed since the mid-20th century, and eruptions producing floating pumice were noted on several occasions.

Information Contacts: JMSA, Tokyo; JMA, Tokyo.