Growth of the October 1 dome continues, resulting in many rockfalls and pyroclastic flows. The level of activity has remained about the same as yesterday.
Excellent weather conditions allowed the glowing from the October 1 dome to be seen from many points around the volcano last night. Most of the eastern and northern faces of the dome were glowing, with continued rockfalls visible. Observations from Whites and Harris showed that the northwest flank of the October 1 dome has become more active. Rockfalls were coming from many discrete points on this flank, and two channels are being developed there. There were also rockfalls on the eastern side, over the remains of Castle Peak.
The seismic activity overnight has been dominated by rockfalls. A few small hybrid earthquakes were also recorded. Rockfall activity with a low level of other seismicity has been seen before, and suggests that the dome is growing quite freely at present.
Visibility is good this morning, although there is continued ash production from the dome. A dome survey using the helicopter is now underway.
The continued high level of rockfall activity suggests that the lava dome within English's Crater is still growing rapidly, and a collapse of part of the dome could occur soon, producing pyroclastic flows and large ash columns. 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.