Report on Karkar (Papua New Guinea) — November 1978
Scientific Event Alert Network Bulletin, vol. 3, no. 11 (November 1978)
Managing Editor: David Squires.
Karkar (Papua New Guinea) Seismicity declines slightly; incandescence and strong vapor emission persist
Please cite this report as:
Global Volcanism Program, 1978. Report on Karkar (Papua New Guinea) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 3:11. Smithsonian Institution.
Papua New Guinea
4.649°S, 145.964°E; summit elev. 1839 m
All times are local (unless otherwise noted)
Strong seismic activity persisted through November. Strongly marked periodic bands on the seismograph records were again evident between the lst and 17th. Tremor was felt at the observation post, 2 km from the volcano, throughout the month. Seismicity began to increase on 10 July (03:9-10), peaked 23 and 24 October, then remained steady or declined slightly 29 October-29 November. Incandescence (first observed 27 September) and strong vapor emission also continued through November.
Geologic Background. Karkar is a 19 x 25 km wide, forest-covered island that is truncated by two nested summit calderas. The 5.5-km-wide outer caldera was formed during one or more eruptions, the last of which occurred 9000 years ago. The eccentric 3.2-km-wide inner caldera was formed sometime between 1500 and 800 years ago. Parasitic cones are present on the N and S flanks of this basaltic-to-andesitic volcano; a linear array of small cones extends from the northern rim of the outer caldera nearly to the coast. Most historical eruptions, which date back to 1643, have originated from Bagiai cone, a pyroclastic cone constructed within the steep-walled, 300-m-deep inner caldera. The floor of the caldera is covered by young, mostly unvegetated andesitic lava flows.
Information Contacts: R. Cooke, RVO.