Montserrat Volcano Observatory

Morning Report
Report for the period 4 pm 18 July
to 7 am 19 July 1997

The alert level system has been revised by zones

Volcano activity overnight has continued at about the same level as yesterday. Small to moderate sized rockfalls signals have been the main type of seismic events recorded on the seismographs. Moderate amplitude tremor on both the St. Patrick's and St. George's Hill seismometer occurred for approximately 30 minutes at 3.54 am. It is likely that this was due to a mudflow, possibly in either Fort Ghaut or Aymers Ghaut. Several high frequency signals with impulsive starts due to thunder have occurred since early in the morning and are continuing. The Chances Peak tiltmeter does not currently show any obvious cyclical behaviour but the long term trend deflationary trend has continued, although at a lower rate. Further rockfalls and moderate pyroclastic flows can be expected later today, and may occur in any direction at any time.

Heavy persistent rain is currently falling as a result of the tropical depression in the region. This seems likely to continue for most of the day, and therefore we can expect to see more mudflows in any of the ghauts on the flank of the volcano. Some of these may be hot as the recent deposits are re-mobilised.

The current area of activity in the crater still makes Mosquito Ghaut and Gages the most likely pathways for pyroclastic flows and surges, but further flows in Tuitt's or Tar River are possible. The Belham River valley is also dangerous and should not be entered. Access to the exclusion zone is completely restricted, and people should stay completely away from the flanks of the volcano. Everyone should continue to stay alert, and listen to Radio Montserrat for any announcements.

Montserrat Volcano Observatory