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 DEPARTMENT OF MINING AND PETROLEUM GEOLOGICAL SURVEY DIVISION 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 falls. ------------------------------------------------------------------ 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.