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Report on Niijima (Japan) — September 1992


Niijima

Bulletin of the Global Volcanism Network, vol. 17, no. 9 (September 1992)
Managing Editor: Lindsay McClelland.

Niijima (Japan) Two weak seismic swarms

Please cite this report as:

Global Volcanism Program, 1992. Report on Niijima (Japan) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 17:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199209-284020



Niijima

Japan

34.397°N, 139.27°E; summit elev. 432 m

All times are local (unless otherwise noted)


Two weak earthquake swarms occurred 5 km WSW and NW of the island on 16 and 22 September. Maximum magnitudes were 3.5 and 3.1, respectively. No ocean-surface anomalies were observed.

Geological Summary. The elongated island of Niijima, SSW of Oshima, is 11 km long and only 2.5 km wide. Eight low rhyolitic lava domes are clustered in two groups at the northern and southern ends of the island, separated by an area of flat-topped domes and a low isthmus of pyroclastic deposits. The Mukaiyama complex on the south and the Atchiyama lava dome on the north were formed during eruptions in the 9th century CE, the last known activity. Shikineyama and Zinaito domes form small islands immediately to the SW and W, respectively, during earlier stages of volcanism. Earthquake swarms occurred during the 20th century.

Information Contacts: JMA.