Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 19 April
to 16:00 20 April 1997
The current alert level is ORANGE

The level of volcanic activity has remained low. Rockfall and pyroclastic flow activity was highest overnight. These events were of a small to moderate size and are inferred to have occurred from the active area of the dome above the Galway's Wall

The broadband network has detected one (1) volcano-tectonic earthquake, eleven (11) long-period earthquakes and twenty-three (23) rockfall/small pyroclastic flow signals. No hybrid earthquakes were detected. These numbers of events are similar to those detected yesterday.

Two regional tectonic events were recorded by the seismic networks at 01:59 am and 04:51 am (local time) this morning. Preliminary locations of these events place the epicentres to the north-east of Montserrat. MVO is awaiting further data from the Seismic Research Unit in Trinidad in order to better establish the locations of these events.

The visibility has been good at times today, but no significant changes to the dome were seen. A small pyroclastic flow at around 3:40pm this afternoon generated a small ash cloud which drifted toward the north. Steaming has been observed from many areas on the dome complex.

No EDM or GPS surveys have been carried out today. The changes reported recently to the lines to the Farrells target require further verification. This will be performed during the early part of the coming week.

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, which makes these areas extremely dangerous. People are reminded to use ash masks when necessary and to listen to radio Montserrat for updates during periods of high activity

Montserrat Volcano Observatory