Date:         Tue, 27 Sep 1994 10:44:55 MST
Sender: VOLCANO 
From: Global Volcanism Network - Smithsonian Institution
Subject:      Rabaul Obs Report, 26 Sept

     RABAUL UPDATE -- 26 September 1994, 1500 PDT (2200 GMT)

              Local time in Rabaul = GMT + 10 hours


The following is taken from a telephone conversation between the
USGS Cascade Volcano Observatory and Chris McKee and Rod Stewart of
the Rabaul Volcano Observatory (RVO).

Current Situation:

     Vulcan is no longer erupting.  No portion of Vulcan has
collapsed.  Tavurvur is still erupting an ash plume.  There is an
ashy haze over Rabaul town.  Seismicity is much decreased, and is
now at about the limit of RSAM detection.
     RVO no longer has the ability to locate earthquakes.  Three
seismic stations remain in operation.  The other stations have been
incapacitated by tsunamis, vandalism, or heavy ashfall.
     About 40 mm of fine powdery ash has fallen at RVO.  The
airport received about 0.5 mm of ash, and the airfall thickens
rapidly towards Matupit Island.

Precursors:

     At 0300 local on Sunday, 18 September, a magnitude 5.1
earthquake occurred beneath the harbor.  An aftershock sequence
from this event merged into an intensifying swarm of high-frequency
(A-type) earthquakes.  Peak intensity of this swarm occurred around
midnight Sunday with about 2 felt events per minute.  The
earthquake swarm tapered off slightly toward morning.  By 0600
Monday the eruption had begun.  Thus only 27 hours of unusual
seismicity preceded the eruption.
     Inspection of the seismograms since the onset of the eruption
revealed that several L-P events had occurred in the 12 hours prior
to the magnitude 5.1 earthquake.

CVO/VDAP Response:
     CVO/VDAP will send three volcanologists, a seismic system
consisting of telemetered seismic stations and a PC-based data-
acquisition and analysis system, several telemetered tiltmeters,
and other deformation monitoring instrumentation, on Wednesday, 28
September.