Seismic activity during this period was, like the previous 24 hours, dominated by rockfalls from the growing dome. While the activity level during the first 12 hours of the report period was as high as that of yesterday, the level for the last 12 hours was lower. More than 43 signals, of variable sizes, interpreted as rockfalls were recorded by most stations of the seismic network. Two rock falls at 01:29 and 15:34 on 31 March 1996 generated significant quantities of ash which were deposited in Plymouth and environs. Visual observations from the Helicopter and from White's confirm that most of the rockfalls are occurring in the east and the west, thus indicating that these are the most active areas of dome growth.
Two long-period and 3 hybrid earthquakes were also recorded but could not be located. One small volcano-tectonic earthquake occurred at a depth of 3 km beneath the Paradise Estate area.
The eastern EDM triangle and the Tar River - Castle Peak line were measured today. The data are still being processed but the results are not expected to differ significantly from yesterday's.
Members of the public are still strongly advised to keep out of the Tar River Valley area.