Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 16 April
to 16:00 17 April 1997
The current alert level is ORANGE

The level of activity has been higher today. Rockfall activity has accounted for the most part of the seismic activity but there has also been a marked increase in long-period earthquakes.

The broadband seismic network has detected 17 long-period earthquakes, an increase of 10 on the number detected yesterday. There have been 54 rockfall/pyroclastic flow signals. This activity was at a low level overnight but has increased through the day. These events originated from the active area of the dome above the Galway's Wall. Some moderate sized ash clouds have been generated which were carried west and north-west by the prevailing winds. The National Oceanographic and Atmospheric Association (NOAA) reported that a faint ash plume could be traced 97 kilometres to the north-west of the volcano at 9:00 am today.

An observation point was cleared today on the east ridge of the South Soufriere Hills in order to gain further information about the rockfalls and pyroclastic occurring from the dome over Galway's Wall. The largest flow seen this afternoon just reached the Galway's Soufriere. It is hoped that one of the MVO's CCTV cameras will be mounted here for remote observation of the area.

The GPS survey of the eastern flanks of the volcano undertaken yesterday has been processed. None of the sites in the survey show any significant changes in position. A long occupation survey has been started today and will conclude tomorrow. The results will be given in a future report.

The alert level remains at ORANGE, because of the unstable dome above the Galway's Wall. Further collapses of the south side of the dome are expected and an escalation of the activity to more serious levels is always possible. Pyroclastic flows could occur without warning in both the Tar River and White River valleys, and these and surrounding areas remain extremely dangerous. Visits to zone C should be kept brief. Zone D should not be occupied tonight.

Montserrat Volcano Observatory