Kuju

Japan - Kyusu

SUMMARY:

Type: composite
Activity: active
Last Eruption: 1996 AD
Rock Type: ?
Eruptive Volume: ? cu km
Location Map from Xerox PARC
Latitude: 33.08 N
Longitude: 131.25 E

GEOLOGIC HISTORY

The Kuju Group consists of more than 20 stratovolcanoes and lava domes NE of Aso Caldera. It has been active in the Holocene. Hosho lava dome is situated near the center of the 20 x 15 km complex. The younges known magmatic activity, about 1700 years ago produced the Kuro-dake lava dome at the east end of the complex, accompanied by pyroclastic flows.

Historic Activity: There are reports of historical eruptions in the 17th century (1662 and 1675). The Japan Meteorological Agency reports that the last confirmed volcanic activity (fumarolic) was in 1738. The area has two operating geothermal power plants.

Recent Activity:

  • In October, 1995, ashfall from phreatic activity was observed in towns as far as 60 km away, but there was no noticeable seimicity. Steam was reported rising 400 m from around mid-slope on the Hosho dome. Additiona activity occured in Nov. and Dec. and juvenile rhyolite glass was recognized in the ash. The highest plumes rose 300 to 600 m above the vent on the N flank of the Hosho dome.
  • Eruption on Jan. 13-14, 1996. Increased seismicity began in late March and continued through December. Low plume and no ashfall.
  • Seismicity in Jan. 1997, increased to levels higher than anything in 1996.

Data Sources

  • Global Volcanism Network (V. 20, No. 9 to V. 22, No. 1).

ADDITIONAL INFORMATION

Last Update: 2/27/00