Seismic activity at the volcano has been low during the period although the dome continues to grow and there is increasing instability of the north-east face. Rockfall activity generated small ash clouds throughout most of the day.
The seismic activity today was very low with only one volcano-tectonic event, one hybrid earthquake and no long period events. Seismic activity has again been dominated by rockfall signals, with 31 rockfall events recorded. Some of these signals were associated with small pyroclastic flows that produced small ash clouds which drifted towards the west with the prevailing winds.
Good views of the crater area were obtained today from the helicopter and from Whites. These indicated that the north-east area of the dome has developed further rockfall chutes and is now crumbling widely. Rockfalls and small pyroclastic flows continue to build up the scree slope at the base of the dome in the south-east and north-east. Overall the dome is still clearly growing, particularly on the top in the south-east.
Earlier today the width of a crack on Chances Peak was measured. This is measured periodically; the rate of opening of the crack is greatly reduced since it was last measured on 1 March, although it has sheared by a further 17 mm in the same period. The damaged extensometer on Chances Peak was also recovered.
Currently a long occupation GPS survey is being carried out with a site on the crater wall above Farrells, 80 m from the dome. Results from this survey will be processed tomorrow.
The observations of increased instability of the north-east of the dome and the height of the south-east portion of the dome indicate that the volcano is active and potentially dangerous. Given that the dome is now large and continuing to grow, a large collapse and pyroclastic flows could happen with little warning. It is dangerous to spend the night in evacuated areas, because the situation could worsen dramatically over a period of a few hours. People entering Zone C are reminded to remain alert at all times, and spend the minimum possible time in the evacuated zone. The Tar River Valley and the upper Galway's area are very dangerous and should not be entered at any time.