Date:         Fri, 23 Sep 1994 12:29:24 MST
Reply-To: VOLCANO 
Sender: VOLCANO 
Comments:     Converted from OV/VM to RFC822 format by PUMP V2.2X
From: Global Volcanism Network 
Subject:      Rabaul Volc Obs report, 22-23 Sept
To: Multiple recipients of list VOLCANO 
Status: OR


  Private Mail Bag, Port Moresby Post Office, Papua New Guinea

                    Rabaul Observatory Report

             1500, 22 September - 0900, 23 September

Volcano and seismic activity remained relatively stable overnight.

Tavurvur: Steady emissions continued with dark gray ash vapor
cloud.  A low rumbling accompanied the stronger emissions.  The ash
column is approximately 2 km high.  The ash plume is being driven
NE over Rabaul town.  At night, incandescent ejecta could be seen
depositing on the NW flank.  Incandescence was rarely visible in
the emission column due to the high ash content.

Vulcan: Intermittent pulses of stronger activity produced jets of
vapor-rich ash cloud at intervals of 5-15 minutes.  Collapse of the
column produced pyroclastic surges which travel up to 2-5 km from
the vent, mostly to the NE.  Generally there is a low ash content
in the eruption cloud.  The column height is about 1.5 km.  At
night incandescent ejecta can be seen depositing around the vent
near the beginning of each pulse.

Beehives: Possible subsidence.

Aerial Inspection, 1620-1640, Thursday, 22 September

     Tavurvur: There is little morphological change.  The vent is
     on the W side of the 1937 crater.

     Vulcan: The only active vent is near sea level on the breached
     crater on the NE flank.  Eruptions are Surtseyan, highly
     explosive, low ash, vapor-rich.  Apparently there is no great
     deformation since the start of the eruption.

Overview: Overall, volcano-seismic activity has been showing a
steady small decline over the last two days.  If current trend
continues, the eruption should persist for at least several more
days.  Visibility over Rabaul is very good, but with occasional ash

This report was transcribed from a hand-written report sent by Ian
Ripper, Head Seismologist in Port Moresby, to the USGS Volcanic
Crisis Assistance Team at the Cascades Volcano Observatory.