Long period earthquakes continued to dominate the seismicity during the past 24 hours and were detected, at regular intervals, on the seismograph stations nearest to the volcano. These earthquakes increased in amplitude, with the majority having magnitudes between 1.0 and 1.5, over the second half of the review period. Several of these larger earthquakes, which are being recorded at a rate of approximately three per hour, were located at depths of between 0.2 and 3.0 km beneath the crater area. Seismic signals associated with rock falls were observed, on the Gages and Chances Peak seismograph stations, throughout the review period. The largest signals of this type occurred at 17:13 on 24 February and at 07:11, 13:33 and 14:33 today. No ash falls were reported from any of these events.
EDM measurements were made today on the eastern triangle between Long Ground, White's Yard and the Castle Peak reflector. These measurements showed a very small movement of the Castle Peak target, continuing the trend established in late November.
Visual observations were made today from the helicopter in moderate visibility. A major block with associated fine light grey ash was noted in the southern moat having fallen from the southeastern whaleback; it is thought that this major rock fall event produced the ash fall over Plymouth overnight on 23/24 February. Small rock falls were noted from this area and from the northern part of the dome.