Report on Karkar (Papua New Guinea) — December 1978
Scientific Event Alert Network Bulletin, vol. 3, no. 12 (December 1978)
Managing Editor: David Squires.
Karkar (Papua New Guinea) Seismicity declines, but incandescence and strong vapor emission continue
Please cite this report as:
Global Volcanism Program, 1978. Report on Karkar (Papua New Guinea) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 3:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197812-251030.
Papua New Guinea
4.649°S, 145.964°E; summit elev. 1839 m
All times are local (unless otherwise noted)
Strong volcano-seismic activity persisted in December, but with lower intensity than in November. After 19 November, periodic banding of stronger and weaker seismicity became indistinct and at times almost nonexistent. Incandescence and strong vapor emission continued, and brief sharp explosion sounds were heard on several days.
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: C. McKee, RVO.