Report for the period midday 20 April to 27 April 2007 Visual observations revealed very little change to the overall dome structure during the period, although fresh deposits can be are present in the head of Tyres Ghaut and in the upper part of the Tar River. As the dome stands, a significant proportion of the dome material remains in the sector above Tyres Ghaut to the northwest. The amount of material here is sufficient to generate pyroclastic flows and surges capable of impacting on the lower Belham Valley.
Recorded seismic activity has remained very low throughout the period. The seismic network recorded just 3 rockfall signals and 1 long-period earthquake.
The sulphur dioxide (SO2) flux rate during the reporting period was variable, ranging between a minimum of 174 tones per day (t/d) to a maximum of 754 t/d. The average of 476 t/d is in line with the long-term average for the eruption.
The alert level remained at 4.