The volcano has been quiet overnight, with only a few volcano-tectonic earthquakes and rockfalls recorded. There has been a slight increase in the level of rockfall activity since about 3 am. A small pyroclastic flow at 4:21 pm yesterday was observed from the helicopter. This flow came from the south part of the October 1 dome, but did not travel far down the south Tar River valley. At the same time, vigorous steam venting from the top of the dome was seen, with ash and steam jetting into the air.
This steam venting coincided with a period of low-level tremor. Another period of tremor occurred between 12:10 am and 2:20 am. These low-amplitude tremor episodes occur every 8 hours, and are increasing in amplitude slowly.
The summit of the volcano is cloudy this morning so that no visual observations have been possible so far.
The southeastern face of the dome remains unstable, and liable to collapse. Further pyroclastic flows are expected during the next few days. The wind direction is the same as yesterday, and so any ash produced today will be deposited to the south of Foxes Bay unless the conditions change. If a major dome collapse happens, it would probably build up over a period of several hours, and would produce large pyroclastic flows in the Tar River valley and heavy ash fall downwind of the volcano. Should the collapse be very large, then an explosive eruption is possible, in the same way that it followed a major dome collapse on September 17/18. At the moment the scientists are confident that zone E, which includes Corkhill and the airport, remains safe. The Tar River area is extremely dangerous, and should not be entered in any circumstances.
The sirens will be tested this afternoon between 3 and 6 pm.