Four (4) earthquakes have been located for this period. These earthquakes occurred at depths of 0 to 4 km (0 to 2.5 miles), scattered in the southern half of the island. The very small, frequent earthquakes observed over the last few days have continued, accompanied by continuous broad-band tremor. This tremor has only been recorded at the Gages seismic station. It is probably associated with continued slow growth of the lava dome in
English's Crater.
Five of the seven EDM lines have been remeasured today. The Tar River line remained stable. The other lines show slight fluctuations which are within the bounds of instrument precision. Low cloud prevented the occupation of the Galway's-Chances Peak and O'Garra's-Chances Peak lines. A new EDM station has been set up at Whites to measure the distance to the Castle Peak reflector.
GPS measurements taken today again showed no change.
Visual observation of the crater area was attempted from Chance's Peak this morning, but thick cloud again prevented any detailed observations. The sound of rock breaking was heard from the crater rim.
Over the last two weeks quite intense and continuous seismic activity has been observed. The decrease in the number of earthquakes and increase in tremor over the last few days suggests a change in the nature of activity within the crater. This increase in seismic activity was preceded by increased deformation measured by the EDM and GPS surveys. These surveys now show only very slow changes. The cloud cover on the volcano means that detailed observations of the crater area have not been possible since Nov 18.
The scientists have reason to believe that a new lava dome may be growing in the area of the July 18th vent, and the collapse of this dome could threaten some areas to the east of the volcano. When the cloud clears the scientists will be able to assess the situation more fully but as a precautionary measure they have recommended temporary evacuation of the Long Ground area.