Report on Suwanosejima (Japan) — March 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 3 (March 1989)
Managing Editor: Lindsay McClelland.
Suwanosejima (Japan) Explosions and ashfall; 1988 activity summarized
Please cite this report as:
Global Volcanism Program, 1989. Report on Suwanosejima (Japan) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198903-282030
Suwanosejima
Japan
29.638°N, 129.714°E; summit elev. 796 m
All times are local (unless otherwise noted)
On 1, 14, and 16 January, residents . . . heard explosions. Ash fell to the S on 21 and 24 January in the the only inhabited part of the small island. On 7 February at 1225, an explosion sound was heard, and on 28 February, a 1,000-m-high ash plume deposited large amounts of ash to the S. At 1640 on 3 March, the crew of a JAS aircraft observed a 2,000-m ash cloud. A summary of [1987-88] explosions and ashfall is shown in table 2.
Table 2. Eruptive episodes at Suwanose-jima, January 1987-October 1988. Courtesy of JMA.
| Date | Time Period | Plume Height (m) | Activity |
| 05 Jan 1988 | -- | -- | Four explosions |
| 16 Jan 1988 | -- | 300 | Five explosions |
| 17 Jan 1988 | -- | 500 | Four explosions |
| 18 Jan 1988 | -- | 300 | One explosion |
| 29 Feb 1988 | -- | -- | Explosion at 1325 caused air shock |
| 08 Mar 1988 | -- | 500 | Eleven explosions accompanied by air shock |
| 28 Mar 1988 | -- | -- | Three explosions accompanied by air shock |
| 13 Apr 1988 | -- | 500 | Five or six explosions per minute |
| 14 Apr 1988 | -- | 500 | 40-50 explosions |
| 15 Apr 1988 | -- | 2000 | TOA Domestic Airlines pilot saw the plume rising 2000 m |
| 16 Apr 1988 | -- | 500 | Ashfall in the S part of the island |
| 18 Jul 1988 | -- | 3000 | Southwest Airlines pilot saw the ash plume rising |
| 09 Aug 1988 | -- | 2000 | Japan Air System pilot saw the plume rising 2000 m |
| 13 Aug 1988 | -- | 500 | Ashfall in the S part of the island |
| 29 Aug 1988 | -- | 300 | Several explosions, ashfall |
| 03 Oct 1988 | -- | 500 | Ashfall in the S part of the island |
| 06 Oct 1988 | -- | -- | Rumbling, ashfall in the S |
| 07 Oct 1988 | -- | -- | Rumbling, ashfall in the S |
Geological Summary. The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan's most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.
Information Contacts: JMA.
