The increased amplitude level of broadband tremor, which was evident at the end of the previous review period, continued until approximately 18:00 on 19 February. A second episode of this increased amplitude tremor was observed at around 11:30 this morning and continued until the end of the present review period. Several small volcano-tectonic earthquakes were detected on the seismograph station nearest to the volcano (Chances Peak). The largest of these occurred at 18:47 on 19 February (magnitude 2.0) and was recorded on the seismograph station at Gages in addition to Chances Peak. Several rockfalls and eruptions continue to be detected on the seismograph stations nearest to the volcano. The largest of these rockfalls occurred at 12:37 on 20 February.
EDM measurements were made on the eastern triangle to Castle Peak today. The changes on the two lines measured; White's Yard - Castle Peak and White's Yard - Long Ground lines, were less than 4 mm. Low cloud cover over the volcano prevented measurement of the other line which completes the eastern triangle.
Visual observations were made from the helicopter during the late morning of 20 February. Moderate to poor visibility prevented good views of all but the south east parts of the dome. Growth continues on the whale-back feature in the south east but appears to have been at a slower rate during the past two days.