Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 7, July 1995

Rabaul (Papua New Guinea)  July volcanism and local seismicity both

New Britain Island, Papua New Guinea
4.27xS, 152.20xE; summit elev. 688 m

Activity remained low during July, with only weak-to-moderate
fumarolic activity at the summit of Tavurvur, and no reported
emissions at Vulcan. Only 11 low-frequency earthquakes originated
from the N part of the caldera. There were 7 high-frequency (M < 1)
earthquakes, mostly from the Namanula Hill and Karavia Bay areas in
the NE and SW portions of the caldera.

Two unusual "hybrid" earthquakes occurred in July. The associated
signals had very high-frequency impulsive onsets, and low-frequency
codas (1.2 Hz) that lasted > 1 minute. At distant stations, only
the low-frequency signals were registered. The first earthquake, on
3 July, occurred at 3 km depth off the S shore of Matupit Island
close to the area of maximum ground deformation. The second, a much
smaller hybrid earthquake, occurred on 25 July and was likely from
the Vulcan area. Ground deformation measurements showed little or
no change throughout July.

Information Contact: Ben Talai, Rabaul Volcano Observatory, P.O.
Box 386, Rabaul, Papua New Guinea.