Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 06 April
to 16:00 07 April 1997
The current alert level is ORANGE

The volcano has continued to be quiet in the last 24 hours, with occasional pyroclastic flows from the south of the dome. Excellent viewing conditions have allowed some of these pyroclastic flows to be observed from the helicopter.

The volcano has been almost entirely cloud-free all day. A few small pyroclastic flows were observed from a steep face at the back of the scar above Galway's Wall, where the current growth seems to be concentrated. The pyroclastic flows began with strong pulses of ash generation, accompanied by the forceful ejection of blocks from the face. These pyroclastic flows are associated with small long-period earthquakes which occur before the pyroclastic flow signal, and are thought be to due to strong gas venting.

The level of seismic activity has been low, with only 4 volcano-tectonic earthquakes and 3 long-period earthquakes. The rockfall and pyroclastic flow activity has continues at about the same level with 29 signals recorded by the seismic network.

A long-occupation GPS survey between Harris and the crater rim at Farrells was completed today, after recording data for 20 hours. The results will be available shortly.

COSPEC measurements were made throughout the day. In the morning, a normal survey was completed along the southwest coast road. This afternoon, a static experiment was carried out, to determine the variation of sulphur dioxide release during the day. The results are still being processed.

Yesterday's volume survey confirmed that the recent pyroclastic flows removed about 1.6 million cubic metres. There has been fresh extrusion of half a million cubic metres in the scar between 3 and 6 April, a rate of about 2 cubic metres per second. This brings the total dome volume to about 49 million cubic metres.

The lower Gages Soufriere was sampled today by MVO staff and visiting scientists from the Guadeloupe Observatory.

Observations of the dome made today suggest that major pyroclastic flows to the south could occur at any time and MVO urges everybody to stay alert. Nobody should sleep in zones A to D tonight, which includes Plymouth, St Patrick's, the central corridor, Harris', Long Ground, Spanish Point and Richmond Hill. Zone E, which includes Corkhill and the airport, remains safe at this time.

Montserrat Volcano Observatory