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Report on Witori (Papua New Guinea) — 5 March-11 March 2003


Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
5 March-11 March 2003
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2003. Report on Witori (Papua New Guinea). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 5 March-11 March 2003. Smithsonian Institution and US Geological Survey.

Weekly Report (5 March-11 March 2003)


Papua New Guinea

5.576°S, 150.516°E; summit elev. 724 m

All times are local (unless otherwise noted)

An aerial inspection of Pago's Witori caldera on 28 February revealed that lava continued to flow from the northwestern-most vent as it had in January. Lateral flow of the N lava lobe had slowed since it was last observed, but there was thickening of the lava deposit along the entire body of the flow. The S lava lobe progressed farther S, but at a very slow rate. All lava was contained inside the floor of Witori caldera. Scientists found that vegetation had died on the S side of the volcano due to volcanic gases blowing to the S, rather than from increased volcanic heat. Vapor continued to be emitted from all vents along the fissure system, and in smaller amounts from the main summit crater. Seismicity continued at low levels, with a decline in the number of earthquakes during the previous 2 weeks. Seismic and GPS data from the remote field site were no longer available as of 27 February due to the theft of four solar panels.

Geological Summary. The Witori caldera (5.5 x 7.5 km) on the northern coast of central New Britain contains the active Pago cone. The Buru caldera cuts the SW flank. The gently sloping outer flanks consist primarily of dacitic pyroclastic-flow and airfall deposits produced during a series of five major explosive eruptions from about 5,600 to 1,200 years ago, many of which may have been associated with caldera formation. The post-caldera Pago cone may have formed less than 350 years ago; it has grown to a height above the Witori caldera rim, and a series of ten dacitic lava flows from it covers much of the caldera floor. The youngest of these was erupted during 2002-2003 from vents extending from the summit nearly to the NW caldera wall.

Source: Rabaul Volcano Observatory (RVO) via the Darwin Volcanic Ash Advisory Center