Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 31 March
to 16:00 1 April 1997
The current alert level is ORANGE

Volcanic activity remained at a high level today, with further pyroclastic flows over the Galway's Wall. A large notch has been cut into the wall, and the scar in the dome has enlarged. The number of long-period earthquakes has increased, and there were reports of a small explosion heard by people around Montserrat. The volcano has been quieter this afternoon, but the situation remains extremely serious, and an escalation to explosive activity could start at any time.

There were 37 long-period earthquakes today, a four-fold increase from the last few days. Many of these long-period earthquakes trigger rockfalls and pyroclastic flows, and the earthquakes may be caused by small explosions from the dome. Three explosions were reportedly heard between 12:30 pm and 1 pm, by a few people around the volcano and ships off-shore. Eighteen hybrid earthquakes and 37 rockfall signals were also recorded.

Large pyroclastic flows over the Galway's Wall occurred at 11 pm last night and 12:30 pm this afternoon. These flows did not travel as far down the White River valley as the flows yesterday, but the flows had a larger surge component causing more extensive damage to the vegetation around the Galway's Soufriere area. This is probably related to the filling of the base of the valley by the considerable volume of deposits in this area. The valley has now filled up to be level with the road at the Soufriere. The flow this afternoon travelled as far as the Great Alps waterfall.

Visual estimates from the helicopter indicate that the scar feature in the dome has been enlarged by about 30 to 50% since yesterday. The deep notch in the Galway's Wall has deepened further, and is now about 80 metres deep.

During most of the morning the level of activity was a high, with nearly continuous small pyroclastic flows. There was almost continuous ash production, and the ash was blown to the north by the light winds. Light ash clouds were reported at up to 20,000 ft during the day, which was carried to the east by high-level winds. Most of the ash was below 10,000 ft.

There has been ash fall in many parts of the safe zone today, and you should wear an ash mask or cover your mouth and nose while in ashy environments.

The situation at the volcano has stabilised somewhat this afternoon, but further pyroclastic flow activity is expected. The amount of material removed from the dome so far is much less that that removed during the explosive eruption in September 1996. However, the scientists judge that the chance of an explosive eruption similar to September 17 in the near future has increased. Residents of Montserrat are urged to listen to Radio ZJB for further updates, and listen for the emergency sirens. 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